greenhouse production florida

7/23/2019 Greenhouse Production Florida

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Florida:A Leading State forGreenhouse Vegeta-bles and SpecialtyCropsBy George Hochmuth

Florida is the leading state forfield production of vegetables, in-cluding sweet corn, cucumbers, and

snap beans, and second for tomato,pepper, watermelon, and straw-berry. The Sunshine State also is aleading producer of greenhouse-grown vegetables (Figures 1 & 2),including herbs, and specialty crops.While some might be surprised tofind Florida among the top green-house states, there are several rea-sons for the success of the green-house vegetable industry. First,Florida has the mild and sub-tropical climates that make produc-tion in the winter, with low heat in-puts, possible. Production in south-ern Florida is possible with negligi-ble heating costs. Also, much of theyear in Florida consists of sunnydays, with longer duration than thenorthern part of the country. Sec-ond, Florida is uniquely situatednear many major metropolitan ar-eas, in the southeastern US and inFlorida itself, that provide readymarkets for high quality products.

Third, greenhouse production inFlorida benefits from a readily avail-able supply of high-quality waterand a very good equipment andsupply industry. The greenhousevegetable industry in Florida hasgrown from 20 to 30 acres in the1970s to almost 100 acres today. Theindustry consists of the full spec-trum of growers from single green-

house units to multi-bay operations 10acres or more in size. The Universityof Florida Institute of Food and Ag-ricultural Services (UF-IFAS) has pro-vided continuous support for thegreenhouse industry from its researchand extension greenhouse facilities inLive Oak and Gainesville. This levelof support for a greenhouse vegetableindustry is matched nowhere else inthe country. This special section ofthe Citrus and Vegetable Magazinepresents some of the information de-veloped by UF-IFAS in support of forgreenhouse vegetable industry inFlorida. Much more information isavailable from UF-IFAS and thoseresources are cited in these articles.Florida has a strong greenhouse vege-table industry and a bright future.George Hochmuth is an associate dean forresearch at UF/IFAS.

Keys to SuccessfulTomato andCucumber Productionin Perlite MediaBy George J. Hochmuth andRobert C. Hochmuth

Tomato and cucumber are popularand important crops for greenhouseproduction in Florida. Profitabilityfrom production of tomato and cu-

cumber requires attention to themany details of crop culture. Themajor keys to successful greenhouseproduction of tomato and cucumberare presented in this publication.This guide is directed at the small tomedium-sized grower with one toseveral houses, but much of the in-formation is also useful for largeroperations. The information in thisguide focuses on tomato (Figure 1)and cucumber (Figure 2), but also

applies to other crops grown in soil-less media, including pepper, egg-plant, melons, lettuce, and cut-flowers. Although this guide focuseson perlite media in lay-flat bags,most of the principles also pertain toother soilless media, such as rock-wool slabs and peat-mix bags (Figure3). In addition, many of these princi-

(Top), Florida Greenhouse tomato ,Beli Farms. (Above), Florida green-house pepper, Mascot Farms.

2006 Greenhouse Production in Florida P1

Figure 1. Greenhouse grown clustertomatoes ready for harvest.


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ples apply to using perlite, pine bark,or similar media in containers, suchas nursery containers. More detailson each subject are available fromthe Florida Greenhouse VegetableProduction Handbook(http://edis.ifas.ufl.edu/

TOPIC_BOOK_Florida_Greenhouse_Vegetable_Production_Handbook).

What is Perlite?Perlite is a mined mineral that is

crushed, then expanded under hightemperature. The crushed material(like kitty litter) expands like pop-corn, is cooled, and sieved into vari-ous grades based on particle size.Perlite is white in color, very lightweight, but has high water holdingcapacity and high aeration proper-ties (Figure 3).

There are negligible differences ingrades of perlite as far as crop per-formance is concerned. Most cropsgrow equally well in horticulturalgrade perlite, coarse or medium size.Perlite is locally available in Florida(e.g., Vero Beach or Jacksonville).Price and sales support might varyamong perlite suppliers.

Perlite can be purchased ready to


vermiculite. The large rockwoolgrowing blocks are not needed inFlorida. Care should be taken tocompletely bury the root media ballof the transplant so that the perlitemedia in the bag does not wick themoisture from the transplant ball.

This is why rockwool growing blocksshould not be placed on the surfaceof the perlite media. Irrigation emit-ters must immediately be placed inposition and directed to wet the per-lite nearest the root ball of the trans-plant. Later on, in a few weeks, theemitter can be moved back a fewinches from the transplants.

Cucumbers can be transplantedinto growing bags, however, cucum-bers also can be seeded directly into

the perlite bags. The germinationpercentage of cucumber seeds isgood enough that direct-seeding canresult in near 100% stands. Direct-seeding saves considerably on trans-plant production costs and the chal-lenges associated with production ofquality transplants. Growers mightwish to start about 5% of their cu-

use in pre-made, lay flat bags, ap-proximately three feet long, six toeight inches wide, and four inchestall. Perlite also can be purchased inbulk bags or in medium-sized bags ofabout four cubic feet. Growers canthen purchase rolls of polyethylene

sleeving material from greenhousesupply companies and make up theirown growing bags. The sleeving ma-terial should be black-on-white withblack on the inside to minimize lightpenetration inside the bag.

Reuse of unsterilized perlite isrisky. Cost in re-use (handling, ster-ilization, rewrapping) is significant.High levels of organic matter in re-used media might affect the irrigationscheduling program early in season

of second crop. Re-used media holdsmore water because of organic matter(old roots). Old root material mightharbor disease organisms from previ-ous crops.

Bag PositioningIn double-row systems, bags are

placed on very slight incline towardleachate collection trough (Figure 4).An alternative system uses a singlebag from which plants are positionedtoward two overhead trellis wires so

two rows of plants evolve. In the sin-gle-bag system, care should be takento provide adequate media volumeper plant. Both systems have beensuccessfully used in Florida.

DrainageSmall slits should be made in the

near bottom of the bags so that excesswater will not build up and drownroots. A large reservoir of water inthe bag is not required so slits can be

positioned to provide nearly com-plete drainage. A large reservoirmaintained in the bag only reducesthe volume of aerated root zone,which plants need to grow optimally.

TransplantingTransplants for the perlite system

can be produced in several mediatypes including rockwool, perlite, or

Figure 2. European CucumbersReady for Harvest.

Figure 3. Various types of growingmedia.

Figure 4. Lay-flat bags of perlite,newly planting with tomatoes.


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cumber crop in transplants so thatmissing direct-seeded plants that failto emerge and develop can be re-placed with a growing transplant.

Irrigation Program

Water Quality.Obtain an analysisof your well water for bicarbonates,pH, iron, sulfur, calcium, and mag-nesium. Water analysis helps deter-mine problems to be anticipatedfrom emitter clogging (fertilizer pre-cipitation and lime deposits, andbacterial slimes). Plants can use thecalcium; knowledge of calcium con-centrations can help with fertilizerprogram. Sometimes, we mightwant to reduce the amount of cal-cium nitrate (Ca) if Ca is high in wa-

ter. Plant leaf analysis should beused to monitor the fertilizer pro-gram or to diagnose nutrient defi-ciencies. For tomatoes, sample themost-recently-matured leaf (aboutthe sixth leaf back from the tip).Sample the whole leaf including thepetiole that attaches it to the mainstem (just as if removing a leaf forleaning and lowering). Try sapanalysis for nitrogen and potassium.Sap squeezed from the petiole of

most-recently-matured leaf shouldread 600 to 1000 ppm nitrate-nitrogen. Ask your local extensionagent for help if you are interested insap testing.

Watering. Irrigation programs fortomatoes growing in perlite can becontrolled by the same equipmentoriginally designed for tomatoes inrockwool. The irrigation sequences


warm spring days.The key to watering frequency is

to balance the amount needed by thecrop with the total needed for cropand leach. A general rule-of-thumb isto leach about 10 to 15% at each irri-gation event for tomato. Leaching

rate for cucumber might need to be20%. Leaching is needed to minimizesalt buildup in the media and to as-sure all bags are fully wetted witheach irrigation event.

Addressing Media-Salt ContentHigh concentrations of salts in the

perlite media can damage plant rootsand upset nutrient and water uptakeby roots. Tomatoes can tolerate fairlyhigh soluble salt content in the root

zone; cucumbers are less tolerant. Aswater is absorbed by plants, somesalts are left behind in the media.These salts are mostly carbonatesand sulfates, e.g. calcium sulfate, cal-cium carbonate (lime), and magne-sium carbonate.

If you are applying a nutrient solu-tion with an electrical conductivity(EC) of 1.0 decisiemens/meter, youcan tolerate a media EC of 1.5. If youare applying a solution of 2.0 EC(full-grown plants), then you cantolerate a media EC of 2.5 to 2.8. Thekey is to watch the EC trends andbegin corrective measures if it con-tinues to climb. Climbing EC indi-cates the need to increase frequencyof irrigation (more water) by raisingthe probe setting of the starter tray orincreasing the irrigation run time.

Remember, the idea is to balanceamount of water needed by the cropwith that needed by the crop plusleach. Maintaining the EC of the me-

dia slightly above the delivered solu-tion shows that you are a good man-ager of nutrient solution delivery. Aplastic leachate-collection tray(Figure 6) can be used to collectleachate for volumetric measure-ments and for nutrient analysis.

It is a good idea to have a few milkjugs positioned around the housewith an extra emitter punched in.

(number and length) can be con-trolled by a timer set to operate theirrigation system a set number oftimes during the day for a predeter-mined length of time. As long asenough water and nutrients can be

supplied to the crop, you will be suc-cessful in production. The problemwith control by timer is that plantswill get water and nutrients whetherthey need the water or nutrients ornot.

Perlite-grown plants can be irri-gated by a starter-tray set-up likerockwool (Figure 5). We have hadgood success using the start-tray andsimilar management schemes tothose for rockwool. Several (40 to 50)small slits are made in the bottom ofa perlite bag and the bag formed intothe start tray. For more informationon irrigation, consult the list of refer-ences at the end of this guide.

The approach to fertilizer and wa-ter management, with either timer orstart-tray, is to apply enough waterand enough nutrients at the correcttime of crop requirement. Usually westart early in the season with nutrientsolutions low (60 to 80 ppm) in Nconcentrations. Frequent, short irriga-

tions will supply enough total nutri-ents to the crop. If a timer is used andirrigations are infrequent (once ortwice per day), then a more concen-trated (100 ppm) nutrient solutionmight be needed.

Fully grown tomato plants mayuse two to three pints of water perday in the winter (including that forleaching) and three to five pints on

Figure 5. Start-tray and probecontrolling off/on cycle of irrigationsystems.

Figure 6. Placement of blackleachate collection trough andneighboring start-tray.


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Paint the jug black to reduce algaegrowth and then scratch a clear linefrom top to bottom of the jug so youcan see the solution level. Calibratethe mark by sequentially pouring inpints of water and marking each pintlevel. The jug helps tell you that thesystem came on that day and it cantell you how much water was ap-plied.

With experience, you can tell howmuch solution should be in the jugon a cloudy day versus a sunny dayor on a winter day versus a springday. Several jugs around the housecan help you get an idea of emitterflow rate uniformity. You mighthave problems if variance amongemitters is greater than 15%.

Get into the habit of performingthe "bag slap test". Pick up the corner

of one bag and flop it up and down acouple of times to get the feel for itsweight. Check a random six bags perhouse every day or so. Lightweightbags indicate not enough irrigationor possibly clogged emitters.

Be sure the emitter spaghetti tubelength and that of the emitterplugged in for the jug are the samelength and size as those for the


probe reservoir. Slimes might createa strand from the reservoir to theprobe, thus maintaining contact be-tween solution and probe, thus re-ducing irrigation cycle frequency.Also, roots can grow into the reser-voir and should be trimmed back.

Starter tray should be placed in anarea of the house representative ofthe house environment, generally atleast 1/4 of the distance from endwalls (Figure 6). Place tray in an alleythat receives frequent traffic, where itwill be observed daily. Many grow-ers do not observe their tray fre-quently enough.

Good Growers Keep RecordsThe most consistent and best pro-

ducing growers are the ones that dogood record keeping (Figure 7). Re-cords help diagnose trends and prob-lems during the present season andthey are invaluable for helping pre-vent repeat problems next season.

Important items for regular inser-tion in the record book are:1. Max-min temperatures outside

and inside.2. Heating fuel consumption.3. "Milk jug" measurements.4. Delivered solution EC, pH, and

nutrient solution concentrations,e.g. N and K.

5. Leachate EC and nutrient con-centrations.

6. Flow meter readings.7. Light meter readings.8. Plant tissue analysis results, e.g.

sap readings.9. Emitter flow rates and uniform-

ity measurements.10. Fertilizer stock recipes and any

adjustments.

11. Volume of leach tank pump out.

Reading the PlantsLearn to identify potential prob-

lems before they occur. Experiencedgrowers know what healthy plantslook like. But, be careful here thatyou don't associate green, vigorousplants with higher yield. Sometimesoverly green, bullish, and thick

plants. Otherwise, different flow ratecould result. Also, be sure to positionopening of emitter, or tube in themilk jug, so that the opening is abovethe level of the irrigation line in be-tween the rows. Otherwise, siphon-ing (forward or backward) could re-

sult in giving false jug readings.Check emitter flow rate and uni-

formity periodically. Use a graduatedcylinder or a measuring cup, collectsolution as it is delivered for severalemitters about the house and checkfor uniformity. They should bewithin 10 to 15% of each other. Also,measure flow rate - amount of solu-tion delivered in 15 seconds, for ex-ample. This can help determine howlong to run the system each cycle.

Remember the idea is to achieveabout 10 to 15% of leach and to man-age the media EC slightly higher thanthe delivered EC.

It takes time and experience to getall the pieces together. Early seasonirrigation program is different fromfull-grown plants. Young seedlingsdo not have large root systems in themedia. Therefore, young seedlings(up to about first blossom) will needto be irrigated on timed basis insteadof by the starter tray. Irrigate at leastthree times a day with enough solu-tion to wet the young root system toencourage roots into the media. Af-ter roots become established in theperlite, then control can be switchedover to the starter tray.

Starter TraysProbe Settings.Generally, shallow

setting is for frequent irrigations anddeeper setting is for less frequent irri-gations. Probe setting is one way to

adjust the irrigation cycles to achievethe desired leach rate, to achieve thedesired amount of water for theplant, and to manage the soluble saltlevel in the media.

Sometimes, a salt deposit builds upon the probe point. This should beremoved regularly as it, in effect,lengthens the probe. Also, algae andbacterial slime might build up in the

Figure 7 Recording environmentaldata helps diagnose problems.


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plants are not what you want andcan actually be an indicator them-selves of a problem (too much fertil-izer). Overly-vegetative plants aremore difficult to manage, moreprone to disease, more prone tobreakage, and typically have moreproblems with fruit quality ).

Knowing what kind of plant willproduce the best fruit with the leasttrouble is the most important key tobeing a successful grower. Thismeans that you must devote a por-tion of each day to being a plantreader and record taker. Write outnotes in your record book aboutwhat you did today (sort of a diary).You will be glad you did when itcomes time to diagnose a problem.Read your book from last year beforeyou start up the new season, and

read the old book periodicallythrough the new season to see whatthe problem was last year and whatyou did to correct it.

Attention to detail most often setsthe good (and profitable) growersapart from the rest. Being observant,recording, and reacting to what youobserve are requisites for successfulgreenhouse vegetable growing.


smaller-sized growing operations.Injectors typically are used with sys-tems involving computer controltechnologies. Proportioners can beused on small-scale operations be-cause they are relatively inexpensiveand operate on the water pressure,

not requiring electric control.Both parallel and series installa-

tions of proportioners can be usedsuccessfully. Proportioners can beinstalled in parallel to avoid prob-lems associated with pressure lossesacross serial proportioners. Parallelinstallation can also be used if morewater is needed than the maximumdelivery of one proportioner.

Valves installed after each propor-tioner can be adjusted to equalized

suction rates. Keep an eye on stocklevels to be sure proportioners areoperating equally. Also, check thenitrogen and potassium levels in theemitters to be sure the proportionersare operating correctly. If you havenitrogen and potassium electrodekits, it might be a good idea to haveall nitrogen in one stock and all po-tassium in the other stock (Figure 8).That way you can determine whichproportioner is malfunctioning andto what degree, by checking N and Kconcentrations in the stock tanks.

Injectors are typically used withlarger operations in conjunction withcomputer control. Injectors can beoperated by the computer controllerto inject various amounts of variousfertilizers and chemicals on demandfrom a computer program.

Back-up Parts.It is always a goodidea to have spare parts around, es-pecially for the more important com-ponents such as proportioners, sole-

noid valves, pressure regulators,emitters, filters, etc. It seems asthough things break down on week-ends, or worse yet, on holidays.

Weather ProblemsMedia Temperature. We have ob-

served problems with plants such aswilting, iron deficiency, reducedgrowth, etc., when the media tem-

Irrigation System DesignThe irrigation system needs to

have all the required parts and in thecorrect design. You need a backflowprevention system (check valve, pres-sure relief, and low pressure drain)for systems into which fertilizers are

to be proportioned.Correctly designed systems allow

for emitters in the house to have uni-form flow rate. All parts should besized properly.

The system should have pressureregulators and pressure gauges. Alsoa flow meter would be a good idea toback up milk jug measurements.

Emitters, lines, filters, valves andinjectors. The key is emitter orificesize. For Florida water, clogging can

be a problem if the emitter orifice istoo small. Therefore, it is suggestedthat the opening to the emitter be atleast 0.05 inches in diameter. Optionsrange from pressure compensating"button" emitters to simple "watersticks" that project a stream of solu-tion from spaghetti tubing (0.05inches inner diameter). It is probablya good idea to have an emitter with afairly high flow rate to minimize runtime of the system and minimizechance of clogging.

Lines should be equipped withflush valves at the end. Open valvesevery week to flush out collected pre-cipitates that might clog emitters.

All good irrigation systems filterthe water delivered to the house. Fil-tration should be about 200 mesh.Filtering protects the proportionersor injectors from damage, from sandor limestone, from the well, and pro-tects emitters from clogging. Fertil-izer from the stock tanks also should

be filtered. Also, be sure to use fil-tered water in the formulation of thefertilizer stocks. Filters should be inblack housing to reduce algae growthin the filter. Always check and cleanfilters regularly; otherwise flow rateof water will be reduced.

Fertilizers are added to the waterby injectors or proportioners. Typi-cally proportioners are used in

Figure 8. Nutrient stock tanks.


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perature drops below 65F. This canhappen during extended cloudy andcold periods. Cool temperatures inthe root zone reduce water and nu-trient uptake. Plants can wilt on asunny day immediately following acool, cloudy period. If this is a prob-

lem, you might want to consider abottom or floor heat distribution sys-tem to help warm the root area. Also,raising bags up onto benches two orthree inches from the floor, so thatthere is air space, will help insulatemedia from the cool floor. Mediatemperature is extremely importantfor proper plant growth. Tempera-ture sensors and warning or alarmsystems are a good investment.

Sunlight. Extended cloudy and

cool days might cause too much de-lay in irrigation cycling. You mightneed to force the system on for a fewcycles on these days. Remember,plants grow slower on these days sothey do not need large amounts ofnutrients and water, but they do re-quire some.

Leachate CollectionSystem Design. Environmental

concerns will probably dictate thatleachate be collected and disposed ofproperly. Bags should drain into acollection trough and leachateshould be removed from the house.Leachate can be collected in a largetank and used to irrigate pasture,garden, vegetable crops, pine trees,nurseries, etc. If the irrigation sys-tem is being operated properly, asdiscussed earlier, then leachateshould be relatively low in nutrientsbut still would represent a potentialpoint-source for pollution, if not dis-

posed of properly.

ComputerizationComputerized controllers can be a

good investment for some growers;however, electronic controllers are agood investment for all growers. Itdepends on your size, on how manyother functions (besides water andnutrient programs) you want con-


measures, rather than to get intosituations of crop rescue. More infor-mation on pest management is avail-able from the references listed at theend of this guide.

Harvesting and HandlingFor maximizing yields and fruit

quality, fruits must be harvested atthe optimum stage of ripeness. Care-ful handling and transport from thegreenhouse to grading and packingarea is very important. Workers mustbe trained in all aspects of properharvesting and handling procedures.Fruits for market must be packed inproper boxes which are appropriatefor the size of the fruits and properly

trolled, and on how much informa-tion (data) you want collected andstored. Small, one, two, or three-house operations can usually doquite well with simple electronic con-trollers for their irrigation systems.Larger operations can benefit from

the control level and data collectionafforded by computerized systems.

Computer-controlled systems col-lect readings of several environ-mental variables, e.g. temperature,relative humidity, sunlight intensity,etc. These measurements are ana-lyzed by the computer and decisionsare made concerning environmentalcontrols, for example, turning on oroff the exhaust fans, deploying shadecloth, or operating the irrigation sys-

tem. As the computer uses the data itcollects to operate the environmentalcontrols, also it stores those data foranalysis and reporting to the green-house operator.

Pest ControlGreenhouse crops are very good

hosts for diseases, insects, and nema-todes. Similar problems to what out-door crop growers face can occur ingreenhouses, and sometimes theproblems can be more serious.Greenhouses afford favorable grow-ing conditions for the plant, and thepests also benefit from favorable en-vironmental conditions. The keys tomanaging greenhouse crop pests fallinto several categories: selecting pestresistant varieties (this pertains todiseases), controlling the environ-ment to reduce diseases (Figure 9),constructing the greenhouse to maxi-mize insect exclusion, practicinggood sanitation in and around the

greenhouse (Figure 10), and applyingappropriate chemical or manual con-trol measures. Greenhouses presentspecial challenges for pest control,e.g., rapidly growing crop, tall crops,enclosed growing space (special chal-lenges for worker protection), andmostly manual operations for pestcontrol practices. Therefore, it is criti-cal to stay abreast of preventative

Figure 9 Horizontal air-flow fan forcirculating air in greenhouse.

Figure 10 Footbath to sanitizeshoes prior to greenhouse entry.


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and attractively labeled

Finishing Up the SeasonClean Up.Media can be dried out

near the end of the season by lettingplants draw out the water. Just turnoff the irrigation system. It will take

four to six days for wilting to begin.Remove plants before they becomebrittle to reduce the mess for theclean up crew. Drying out the bagswill make them easier to handle.

Perlite media should be disposedof properly. Although, we have hadsuccess using the old media for asecond crop, the practice is risky.Perlite can be distributed on a fieldand incorporated into the soil. Perlitecan be used for soil mixes for con-

tainer production of woody plants.Irrigation lines and emittersshould be cleaned with acid to re-move lime deposits and fertilizerprecipitates. A 1% acid solutionshould work in most situations.Acidification should be done at endof season since acidic solutionsmight injure plants. Flush systemfollowing acidification.

Additional InformationMore information on hydroponic

vegetable production is availablefrom the Cooperative Extension Ser-vice of UF/IFAS. The following is alisting of sources for this informa-tion.

Visit the North Florida Researchand Education Center - SuwanneeValley website at http://nfrec-sv.ifas.ufl.edu.


Production ofGreenhouse-grownPeppers in FloridaBy Elio Jovicich, Daniel J. Cantliffe, Ste-

ven A. Sargent, and Lance S. Osborne

In the US, the consumption of highquality red, yellow, and orange bellpeppers (Capsicum annuum) has beenincreasing dramatically in the pastdecade. To satisfy consumers de-mand, Mexico, The Netherlands,Canada, Israel, and Spain have beenexporting high-quality greenhouse-grown peppers into the U.S. In Flor-ida, high market prices, consumer

demand, and a suitable environmentfor growing colored peppers underprotected agriculture have encour-aged greenhouse growers to con-sider the economic viability of thiscrop. In the past years, high qualitycolored peppers (greenhouse-grown)shipped to Miami averaged year-round wholesale fruit prices 3 timesgreater than colored field-grownfruits and 5 times greater than field-grown green fruits. With mild winter

regions, Florida's greenhouse indus-try benefits from growing plants andproducing fruits under a relativelyoptimal plant environment duringmuch of the year (Fig. 1).

The total area in Florida withgreenhouse-grown peppers ex-panded to 25 acres in the year 2002.This area could increase in the nearfuture, in part as a consequence ofgreater demand for specialty vegeta-

ResourcesFlorida Greenhouse VegetableProduction Handbook, Vol 1

Introduction, HS 766

Financial Considerations, HS767

Pre-Construction Considerations,HS768

Crop Production, HS769 Considerations for Managing Green-

house Pests, HS770

Harvest and Handling Considera-tions, HS771

Marketing Considerations, HS772

Summary, HS773

Florida Greenhouse VegetableProduction Handbook, Vol 2

General Considerations, HS774

Site Selection, HS775

Physical Greenhouse Design Consid-

erations, HS776 Production Systems, HS777

Greenhouse Environmental DesignConsiderations, HS778

Environmental Controls, HS779

Materials Handling, HS780

Other Design Information Re-sources, HS781

Florida Greenhouse VegetableProduction Handbook, Vol 3Preface, HS783

General Aspects of Plant Growth,

HS784 Production Systems, HS785

Irrigation of Greenhouse Vegetables,HS786

Fertilizer Management for Green-house Vegetables, HS787

Production of Greenhouse Toma-toes, HS788

Generalized Sequence of Operationsfor Tomato Culture, HS789

Greenhouse Cucumber Production,HS790

Alternative Greenhouse Crops,

HS791 Operational Considerations for Har-

vest, HS792

Enterprise Budget and Cash Flow forGreenhouse Tomato Production,HS793

Vegetable Disease Recognition andControl, HS797

Vegetable Insect Identification andControl, HS798

George J. Hochmuth, Associate Dean for Extensionand Robert C. Hochmuth, Multi County Extension

Agent, North Florida Research and EducationCenter Suwannee Valley, Live Oak, FL 32060


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ble crops, the ban of methyl bromide,and increases in urban sprawl andsubsequent high prices for arableland. For the past 5 years, pepperranked first in production area in thestate's total greenhouse area dedi-cated to vegetable crops (followed bytomato, cucumber, and lettuce).A greenhouse production system ofpeppers differs greatly from the tra-ditional field pepper cultivation sys-tem where plants are grown on poly-ethylene-mulched beds and withdrip irrigation, and where fruits are

typically harvested at the maturegreen stage of development (Fig. 2).

Depending on the region's climateand crop-growing season, green-houses can be a means to economi-cally maintain a warm environmentduring cool seasons, to protect pep-per plants from rain, wind, and highsolar radiation, and to retain pollina-tors and beneficial insects while ex-


duction costs per unit of greenhousefloor area.

The production of soilless green-house-grown bell peppers, alongwith the production of other spe-cialty crops such as strawberries, Ga-lia melons, and Beit Alpha cucum-bers, have been and continue beingresearched at the Horticultural Sci-ences Protected Agriculture Center(http://www.hos.ufl.edu/ProtectedAg)at the University of Florida, IFAS, toprovide information and assist exist-ing and intending greenhouse grow-ers.

Greenhouse StructuresIn Florida, there is a trend cur-

rently for using high-roof, passivelyventilated greenhouse structures (13-ft high or more to the roof gutter) for

protected vegetable production (Fig.5).

The greenhouses are covered withpolyethylene, which is replacedevery 3-4 years. The polyethylene is aUV-absorbing type of film which canreduce the spread of insect pests andvirus diseases in covered crops. Thepolyethylene film also prevents wa-ter condensation from forming on

cluding unwanted insect pests (Fig.3). In greenhouses, pepper fruits areharvested with full maturation color(Fig. 4), and fruit yields are greater, ofhigher quality, and usually producedat a time of the year when productionin the field is not possible and marketprices for peppers are highest.

Marketable fruit yields will varywith greenhouse location, growingseason, plant density, trellis system,cultivar, irrigation, and fertilizermanagement. Current marketablefruit yields of 1.6 to 3.0 lb per square

foot and potential yields of 4 lb/ft2can be obtained in Florida in passiveventilated greenhouses with low useof fuel for heating. However, becauseof the higher costs involved withgreenhouse growing systems com-pared to growing in the open field,greenhouse growers have to managetheir crops to maximize fruit yieldand quality while minimizing pro-

Figure 1 High quality colored bell peppers can be produced in high-roof,passively ventilated greenhouses. Credits: Elio Jovicich

Figure 2 Field grown bell peppers in southeast Florida where fruits are har-vested at the mature green stage. Credits: Elio Jovicich

Figure 3 Greenhouse grown pep-

pers in Florida for harvesting fruitsduring an extended growing season.Credits: Dr. Steve Sargent


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the film surface. The side walls androof vents can be covered with insectscreens (50 mesh) to restrict the en-trance of pest insects and to keepbeneficial insects, such as bumble-bees (Bombus spp.), within the green-

house.These high-roof greenhouse de-signs are less expensive and moresuited to be used in regions withsubtropical and tropical climatesthan structures covered with glass orpolycarbonate. Costs of passivelyventilated greenhouses can range asmuch as 80% less per square footthan the types of greenhouses thatseek maximum climate control.Greenhouses with passive ventila-tion and heating provide a level ofclimate control that enables plants tosurvive and produce at economicallysufficient yields.

CultivarsThe sweet pepper cultivars most

commonly used in greenhouse pro-duction are hybrids that have bell-shaped or blocky-type fruits, withred, orange, or yellow color whenthey are mature (Fig. 6). Cultivarswhich produce purple, brown, or

white fruit are less commonlygrown, as they have less market de-mand. Cultivars should be selectedfor a growers ability to market themas well as pest and disease resistanceor tolerance, low susceptibility tofruit disorders, and yield and qualityperformance. Some of the commonlyused cultivars are Parker, Triple 4,Cubico, and Lorca for red; Kelvin,


from mid July or early August toMay. Long crops of up to 300 daysare transplanted during the secondor third week of July with a first har-vest about the middle of October,ending in late May. Depending on

fruit prices and on the quantity andquality of the fruits harvested, pro-duction may be extended until June.In Table 1, three production schemesfor greenhouse-grown peppers thathave been used in Florida are pre-sented.

High temperatures and humidityduring July and August adverselyaffect production but are good foryoung plant growth. With some cul-tivars, percentages of unmarketablefruits increase during the late spring,mainly due to a higher incidence ofblossom-end rot and fruit cracking.Fruit set can also be low during sum-mer due to high rates of flower abor-tion under high temperatures. Airventilation and shade materials for30% shade help reduce high tem-peratures during the late spring,summer, and early fall. Cold weather

for yellow; and Neibla, and Emily,for orange fruits. New pepper culti-vars for greenhouse production areintroduced every year by seed com-panies. For short season crops, somelocal growers have been evaluating

the performance of field pepper culti-vars grown under greenhouse pro-duction systems.

In a pepper cultivar trial conductedin a passively ventilated greenhousein Gainesville, the total marketableyield was acceptable for all 23 culti-vars tested when grown and har-vested during the winter months innorth central Florida (manuscript byShaw and Cantliffe (2002) accessibleat http://www.hos.ufl.edu/protectedag/PepperCultivars2000.pdf. The red and yel-low cultivars produced fruit yields of1.8 to 2.2 lb per ft2, the orange culti-vars had yields of 1.4 to 2 lb per ft2and the chocolate and purple culti-vars produced 1.6 lb per ft2. Whencomparing cultivars for those withthe highest yield and fruit qualitycharacteristics with low amounts ofculls or other disorders, the best redcultivars were Lorca, Torkal, Triple 4,and Zambra; yellow cultivars werePekin, Kelvin, Neibla, Bossanova,

and Taranto; and orange cultivarswere Paramo, Lion, and Boogie. BothChoco and Mavras produced highyields and quality fruit, which maybe desirable for specialty market pro-duction.

Growing SeasonsThe most common greenhouse

pepper production season extends

Figure 4 Greenhouse grown bellpepper ready to be harvested. Cred-its: Elio Jovicich

Figure 5 Passively ventilated greenhouse at the Horticultural Sciences Pro-tected Agriculture Center, Plant Science Research and Education Unit, UF/IFAS, Citra FL. Credits: Elio Jovicich

Figure 6 Bell pepper fruits fromcultivars that mature to different col-ors. Credits: Elio Jovicich


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during winter can also adverselyaffect the set of marketable fruits dueto poor pollination, and delay matu-

ration and earliness in production. Incentral and north Florida, optimumdaytime temperatures required forpepper production can be easilyachieved in winter while optimumnight temperatures cannot and,therefore, heating during the nightmay be necessary to increase fruityield and improve fruit quality.

Soilless Culture SystemsGreenhouse pepper crops in Flor-

ida are grown in soil-less culture.Thus methyl bromide is not needed,yet problems with soil borne dis-eases, and insect and nematode pestsare avoided. The plants are grown incontainers filled with soil-less mediasuch as perlite, pine bark, or peat


with soil-less culture, the concentra-tion of nutrients in parts per million(ppm, being 1 ppm = 1 mg per L 1 ozper 7,462.7 gal) can be for N: 70, P:50, K: 119, Ca: 110, Mg: 40, and S: 55,starting when transplanting the seed-lings. In plants at full production, the

nutrient concentration levels canreach N: 160, P: 50, K: 200, Ca: 190,Mg: 48, and S: 65 ppm, respectively.The irrigation solution also providesthe plants with micronutrients. ThepH of the irrigation solution is main-tained at values between 5.5 and 6.5,and the EC, depending on the nutri-ents concentration levels, will havevalues between 1.5 and 2.5 mS percm.

At the time of transplanting, seed-

lings can be irrigated about 10 timesper day delivering about 1.3 fl oz perirrigation event. As plants grow andseason temperatures increase, irriga-tion frequency and volume per irri-gation event can be increased up to40 times per day and 2.5 fl oz perirrigation event, respectively. Duringfull production and under intensesunlight (warm weather), volumes ofnutrient solution per plant per daymay reach up to 1.5 gal. Irrigationevents can be scheduled by usingdifferent control systems such as atime clock, a starter tray, or a control-ler that irrigates based on solar radia-tion. An excess of irrigation leadingto 15 or 20 % drainage from the con-tainer at the end of a day ensures

mixes. The media can be reused forseveral crops (two to three) if diseasecontamination does not occur. Thecontainers used are nursery pots (3and 4 gal) with one plant per pot (Fig.7), or flat polyethylene bags of about3 ft long (5 gal) with 3 to 4 plants per

bag. The plant containers can bealigned in single or double rows, onenext to the other one, leading to plantpopulation densities of 0.27 to 0.36plants per square foot.

In local trials with greenhouse-grown peppers, fruit yields fromplants grown in 3-gal pots or 5-galflat bags have been similar. Also,similar marketable fruit yields wereharvested from plants grown in vari-ous substrates, such as perlite, pine

bark, or peat-perlite mixes. Pine bark,milled and sieved to particle sizessmaller than one square inch, hasshown to be a promising mediumbecause of its low cost, availability,lack of phytotoxicity, and excellenceas a plant production media.

Irrigation & FertilizationPepper plants in soil-less culture

are fertigated frequently with a com-plete nutrient solution. Nutrient solu-tion concentrations are similar tothose used for tomatoes grown insoil-less culture. The concentrationsof most of the nutrients required bypepper plants in larger quantities areincreased with plant growth. For ex-ample, in the irrigation solution used

Figure 7 Pepper plants grown in 3-gal nursery pots filled with pinebark, and irrigated with a completenutrient solution. Credits: Elio

Jovicich

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Fall toSummer

E T H

Winter toSpring

J E T

T H E

E T H

T: Transplant, H: Harvest and E: End of the crop.

Spring toSummer &Fall toSpring(2 crops)

Table 1 Commercial production schemes of greenhouse grown bell pepper used in Florida.


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sufficient solution delivery through-out the crop and avoids a high con-centration of salts in the soil-less me-dia. Systems for recycling the fertiga-tion solution are available and pro-vide a more sustainable use of waterand nutrients. With these "closed"irrigation systems, the solution thatdrains from the pots is sanitized andthen the pH and EC are corrected tomeet the plant needs. Subsequently,the nutrient solution can be recycledon the same pepper crop.

TransplantingDeposits of salt at high levels and

excessive irrigation near the cotyle-donary node level can promote local-

ized epidermal injuries on a swollenstem base where then fungal infec-tions lead to basal stem rots and sud-den plant wilts. This phenomenon(symptoms of basal stem swellingand epidermal wounds at the base ofthe stem) has been named "Elephantsfoot." For more information on the"Elephant's foot" disorder, pleaserefer to this UF/IFAS Extension pub-


tem consists of forming a plant withtwo main stems by removing one ofthe two shoots developed on eachnode and leaving one or more adja-cent leaves per node. The pairs ofstems are kept vertically by the useof hanging twines that are wound

around the stems as they grow. The"V" trellis system is used by Dutchand Canadian growers.

Spanish, Israeli, and some Mexicangrowers generally trellis the pepperplants using the "Spanish" system. Inthe "Spanish" trellis system, the plantcanopy is allowed to grow withoutpruning. The plants are verticallysupported by a structure of polesand horizontal twines extended onboth sides of the plant rows. Laborrequirements for the Spanish systemare reduced minimally by 75% of thelabor used compared with the "V"trellis system. In a spring crop inFlorida, total marketable fruit yieldswere similar regardless of the trellissystem. Moreover, the yield of extralarge fruits was actually greater inthe plants trellised to the "Spanish"system than in the "V" trellis system.The percentage of fruits with blos-som-end rot at the end of the springwas also lower in the nonpruned

plants.

PollinationPepper flowers are self pollinated,

but the use of bumblebees inside thegreenhouse help to ensure the set ofhigh quality fruits, especially duringthe cool season when pollen viabilityis lower (Fig. 9). Bumblebees feed onnectar and pollen and their daily ac-

lication, "Elephant's Foot, a Basal StemDisorder in Greenhouse-Grown Bell Pep-

pers," at http://edis.ifas.ufl.edu/HS206.To avoid injuries to the plant stembelow the cotyledonary leaves, seed-lings (about 35 days-old, 5-7 trueleaves) should be transplanted intothe soilless culture substrate to thedepth of the first leaf node. To reducecreating a humid environment closeto the base of the stem, irrigationemitters placed near the seedlingstems at transplanting can be gradu-ally moved back (2-3 inches) from thebase of the pepper plants over a threeweek period.

Pruning & Training

Greenhouse pepper cultivars gen-erally have an indeterminate patternof growth. Because the plants cangrow up to 6-ft tall during a growingseason of 250 days, they need to besupported vertically. Pepper plantscan be trellised to the Dutch "V" sys-tem or to the "Spanish" system (Fig.8).

Trellising plants with the "V" sys-

Figure 8 Pepper plants trellised to the V system (left) and in a double rowtrellised to the Spanish system (right). Credits: Elio Jovicich

Figure 9 Use of bumble bees to in-crease set of high quality fruits.Credits: Elio Jovicich


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tivity is naturally timed with the pe-riod when flowers are ready to be

fertilized. Although one bumblebeehive (containing about 60 bees) per16,000 square feet might seem costlyto the grower, pollination done byworkers would be less efficient andmuch more expensive. The expectedlife span of the colony is 8 to 12weeks. The hive should be placedunder shade in summer and in thesun in winter and isolated from ants.The hives contain a supplement foodfor the bees during periods of lowabundance of flowers because over-visited flowers may lead to fruitswith cork-like spots at the blossom-end.

Fruit DisordersOptimal environmental conditions

for the crop may not always be pos-


ify flower structure making self polli-nation less effective. Use of bumble-bees for pollination can help greatlyto improve fruit shape.

Blossom-end rot can be caused byreduced absorption and translocationof calcium into the fruit (Fig 13). Cal-

cium deficiency in the fruit occurs asa result of one or more factors, suchas low Ca concentration in the solu-tion or media, excessive salinity inthe irrigation solution or media, ex-treme moisture fluctuations in themedia, and rapid plant growth dueto high temperatures and solar radia-tion. The localized deficiency of Ca,which occurs at the sides and lowerparts of the pepper fruit, manifestitself as regions with collapsed tissue

that gradually turn black, making thefruit unmarketable. Pepper cultivarshave different levels of susceptibilityto the disorder. The disorder in pep-per is difficult to prevent with foliarapplications of Ca.

Harvesting, Packing, & MaintainingPostharvest Fruit Quality

Throughout the harvest season,pepper plants will have ripenedfruits in flushes or waves of produc-tion. Under warm environments,

ripened fruits can be picked once ortwice a week (up to 3 fruits per plantat each harvest). Sharp pruning scis-sors or knives should be used to cutthe fruits at the level of the abscissionzone on the fruits peduncle (Fig. 14).Pepper fruits with intact pedunclesare more resistant to bacterial soft rotthan those with torn or partial pe-duncles. Non-marketable fruitsshould be removed from the plantsas soon as they are observed. How-

ever, in the case of fruits with blos-som-end rot, some growers advisenot to remove young fruits with thisdisorder as this practice will promotea rapid vegetative growth, whichmay lead to Ca deficiency in devel-oping fruits, thus increasing the inci-dence of blossom-end rot.

Marketable fruits are graded bydiameter (maximum distance across

sible to reach with no heaters or with-out a greenhouse structure that en-sures good ventilation. Pepper fruitsmay develop physiological disorderssuch as "color spots," cracking, blos-som-end rots, and flat-shaped fruits.Most of these disorders are caused by

environmental stresses during fruitdevelopment but can be minimizedby using cultivars that have less sus-ceptibility to stress.

Yellow spots can occur on theouter surface of the fruit (Fig. 10). The"color spots," sometimes already visi-ble on green fruits, turn yellow as thefruit matures, reducing the visualquality of the fruits for consumers.High incidences of this disorder oc-curred in summer, and in plants

grown at high densities, under shade,or fertilized with high levels of N;avoid pepper varieties susceptible tothis disorder.

Fruit cracking results from rup-tures on the cuticle at the blossom-end (radial cracking) or all over thefruit surface (russeting) (Fig. 11). Pep-per plants which receive too muchwater can have higher incidences offruit cracking. Pepper cultivars withthick-walled fruits (>8 mm) are moresusceptible to cracking than cultivarswith thinner fruit walls.

Flat pepper fruits are caused bylow temperature (Fig. 12). Night tem-peratures of around 64F ensure anideal seed set and fruit shape. Low-night temperatures decrease pollenviability in pepper flowers and mod-

Figure 10 Color spots in red bellpeppers. Credits: Elio Jovicich

Figure 11 Fruit cracking in bell pepper. Radial cracking (left) and russeting(right). Credits: Elio Jovicich


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shoulders). Fruits with greater sizebring higher prices. Fruit grades can

follow the USDA standards for field-grown peppers or can be based onclassifications based on diameterranges similar to greenhouse pep-pers imported from Holland (extra-large, diameter >3.3 in; large, 3 to 3.2in; medium, 2.5 to 2.9 in; and small,2.2 to 2.4 in). Extra large fruits gener-ally weigh about half a pound, al-though individual fruit weight will


house peppers in Florida are broadmite (Polyphagotarsonemus latus),twospotted mite (Tetranychus urticae),western flower thrips (Frankliniellaoccidentalis), melon thrips (Thrips

palmi), green peach aphid (Myzuspersicae), melon or cotton aphid

(Aphis gossypii), silverleaf or sweetpotato whitefly (Bemisia argentifolii),pepper weevil (Anthonomus eugenii),fungus gnats (Bradysiaspp.), and sev-eral lepidopterous pests.

Common fungal diseases are pow-dery mildew (Leveillula taurica) andFusarium (F. oxysporum and F. so-lani). For more information on F. so-lani in greenhouse-grown peppers,please refer to this UF/IFAS Exten-sion publication, "Fusarium Stem Rot

of Greenhouse Peppers," at http://edis.ifas.ufl.edu/CV276. Western flowerthrips can transmit tomato spottedwilt virus (TSWV).

Insecticides are available to controlinsect and mite pests. However,many chemicals negatively affectbumblebees, beneficial organisms,and the pepper plant itself. Also,crop reentry after using pesticidescan complicate management whenplants have to be accessed frequentlyfor pruning, training, and harvesting.Some products, such as soaps, oils,and sulfur, often are phytotoxic topepper plants in the greenhouse.

Research in the Protected Agricul-ture Project at the University of Flor-ida (http://www.hos.ufl.edu/ProtectedAg )and at the Mid-Florida REC (http://mrec.ifas.ufl.edu/lso/) is evaluating bio-logical control practices used in otherregions and crop systems to mini-mize or avoid the use of pesticides.Augmented biological control in-

volves the release of living organ-isms that will limit the abundance ofother living organisms. In pepper,melon aphids have been successfullycontrolled by releasing a parasiticwasp, Aphidius colemani. Twospottedspider mites were controlled by re-leasing a predatory mite, Neoseiuluscalifornicus. The appearance of lepi-dopterous pests is greatly reduced by

vary with cultivar.Peppers should not be submerged

in water during the transfer to thepacking line since water can easilyinfiltrate the hollow pod and causepostharvest decay. Overhead spraywith clean water works well for

washing; free water should be re-moved prior to packing. Pepper fruitsare often individually labeled andpacked in single or double layers in11-lb corrugated cartons ( Fig. 14 ).

Pepper fruit respiration rate can bereduced to a minimum by loweringthe product temperature. Optimalstorage conditions are 45F and 90 to95% relative humidity. To avoid chill-ing injury, fruits should not be storedat temperatures below 45F. Maxi-

mum pepper fruit storage life is 2 to 3weeks under the most favorable con-ditions. Symptoms of chilling injuryare water-soaked spots, pitting, ortissue collapse. Extensive decay de-velops on chilled peppers when theyare removed from low-temperaturestorage. Temperatures above 55Fenhance ripening and spread of bac-terial soft rot.

Rapid cooling of harvested sweetpeppers is essential in reducing mar-keting losses. Pre-cooling by forced-air is the preferred method. Peppersare very susceptible to water loss.Symptoms of shriveling may becomeevident with as little as 3% weightloss. Pre-cooling and storage in ahigh relative humidity (90 - 95%) willminimize weight loss. Peppers can bewaxed, but only a thin coating shouldbe applied. Waxing provides somesurface lubrication which reduceschafing in transit. Water loss can alsobe limited by packing peppers into

cartons with moisture-retentive linersor into perforated polyethylene bags.

Pests and DiseasesPests are reduced but not elimi-

nated in screened greenhouse struc-tures. Transplants must be free ofpests and weeds must not be presentinside the greenhouse. The major ar-thropod pests observed in green-

Figure 12 Bell shaped pepper fruitwith abundant seeds (top, right andleft) and flat parthenocarpic fruit(bottom, right and left). Credits: Elio

Jovicich

Figure 13 Blossom-end rot in bellpeppers. Credits: Elio Jovicich


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using insect screens on the green-house vents. When adult moths are

present in the greenhouse, the larvalstages can be controlled by repeatedtreatments with Bacillus thuringiensis.B. thuringiensis can also be appliednear the base of the plants to controllarvae of fungus gnats. Releases of aparasitic wasp, Eretmocerous eremicus,were used to maintain low popula-tions of silverleaf whitefly. Currentresearch evaluates using predatorymites N. californicus and Neoseiuluscucumeris for the control of broadmites. N. cucumeris and big-eyedbugs, Orius spp., can be used to con-trol western flower thrips.

Compared to the use of pesticides,with biological control, insects donot develop resistance as they do tocertain insecticides. Also, restrictedreentry periods to the greenhousedue to the use of insecticides areeliminated, the environment forworkers is safer, and harvest prod-ucts can be labeled "pesticide free,"which may attract higher prices

and/or increase consumer demand.The use and success of biologicalcontrol will require that the crop isscouted frequently to determinepresence and to estimate populationdensities of crop damaging pests andtheir natural or introduced enemies.Combining the use of bumblebeeswith natural enemies does not pre-sent any problems but the use of


AlternativeGreenhouse CropsBy Robert C. Hochmuth

A significant greenhouse vegetableindustry has flourished in Florida for

almost 20 years. A statewide surveyconducted in 1991 by the Universityof Florida indicated 66 acres ofgreenhouse vegetables were pro-duced in Florida. European seedlesscucumber (Figure 1) and tomatoes(Figure 2) represented 96% of thetotal acreage in 1991.

A survey conduced in the samemanner in 2001 indicated the totalstatewide acreage was 95 acres.

However, tomato and cucumber rep-

resented only one-third of the totalacreage in 2001. The leading green-house vegetable crop as of 2001 wascolored bell pepper. Herb produc-tion (primarily basil) had increasedto nearly 17 acres which was greaterthan European seedless cucumberand only slightly less than tomato(18 acres). Lettuce was produced in7 acres of greenhouses and straw-

chemicals may have direct or indirecteffects on the bumblebees and/or

natural enemies. Information aboutthe side effects that agriculturalchemicals have on bumblebees andon biological control agents can beprovided by the companies that sup-ply these organisms.

The production of greenhouse-grown peppers represents an alterna-tive crop in Florida. In the ProtectedAgriculture Project at the Universityof Florida, ongoing research ongreenhouse-grown peppers on pro-duction systems, fruit quality, culti-vars, nutrient and water manage-ment, integrated pest and diseasemanagement, post harvest, and mar-keting are being evaluated. Currentand past research, publications, andlinks to products used for peppergreenhouse production and otherspecialty crops are posted in an up-to-date Web site at http://www.hos.ufl.edu/ProtectedAg.

Elio Jovicich, graduate student, Daniel J.

Cantliffe, professor and chair, Steven A.Sargent, professor, Horticultural Sci-ences Department, Lance S. Osborne,Entomology and Nematology Depart-ment, Cooperative Extension Service,Institute of Food and Agricultural Sci-ences, University of Florida, Gainesville,FL 32611.

Figure 14 Fruit harvest by cutting at the peduncles abscission zone (right)and fruits graded, labeled, and packed in 11-lb cartons (right). Credits: Dr.Steve Sargent

Figure 1 Beit Alpha cucumber, sev-eral fruit per node.


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berry in one acre. The complete de-tails of these surveys are available athttp://nfrec-sv.ifas.ufl.edu.

In addition, to the big threegreenhouse vegetable crops; pepper,European seedless cucumber, andtomato, other alternative crops have

become very important in NorthAmerican greenhouses. This is espe-cially evident in Florida and isdriven by the unique markets in theSunshine state.

Large urban centers such as Or-lando, Miami, Tampa, Jacksonville,and others provide marketing op-portunities for many high value al-ternative greenhouse crops (Figure3) for restaurants and specialty eth-nic markets. The abundant Floridacruise ship industry also provides aclose market for many high valuespecialty crops. The demand for thehighest quality is often difficult tomeet by any other production sys-tem than greenhouse culture. Sev-eral crops, other than the big three,are being successfully grown andmarketed now and others are beingevaluated by the University of Flor-ida. A discussion of those crops willfollow next.

Mini CucumberMini cucumber (Beit Alpha types)

(Figure 1), a smaller version of thestandard European seedless cucum-ber has become a popular new crop.New to the U. S. is the Beit Alphacucumber, a major cucumber typegrown in Israel and exported toEurope. The Beit Alpha cucumberoriginated in Israel and is now being


cultivars are being evaluated by R.Hochmuth this spring at the NorthFlorida Research and Education Cen-ter Suwannee Valley near Live Oakand a dozen others have been evalu-ated by D. Cantliffe and N. Shaw,Dept. of Horticultural Sciences,

Gainesville, FL.

Lettuce and Other Leafy GreenVegetables

The traditional greenhouse lettucecrop in Florida and elsewhere is abibb heading type grown in NFTchannels (Figure 3) or in a floatingsystem (Figure 4). The product isusually sold as a living plant withthe roots still attached and packagedin a bag or special plastic clam shell.

Lettuce is a fast crop, typically taking30 to 35 days from seeding to har-vest. Growing lettuce in the warmseason in Florida makes the disorder,leaf tip burn difficult to manage.Environmental controls for tempera-ture and light and cultivar selectionare critical to properly managing tipburn. Lettuce acreage in Florida wasabout 1 acre in 1991, 2 acres in 1996,and 7 acres in 2001. The later in-crease was mostly due to one largenew operation in Central Florida.

Opportunities for greenhousegrowers to supply other specialtyleafy green vegetable crops is alsoincreasing. Recent educational pro-grams in Northern Florida connectedgrowers with restaurant chefs. Theseprograms revealed great interestamong chefs to purchase specialtysalad greens. Developing production

distributed throughout the world.Beit Alpha cucumbers are hybridsthat are gynoecious and parthenocar-pic, thus they do not need to be polli-nated for fruit development. Thefruit is seedless and has a thin skinlike the European cultivars, but does

not require a plastic shrink wrappingfor prevention of dehydration afterharvest. This is a major advantage inthe cost of post harvest handling andmarketing. Fruit production is pro-lific for Beit Alpha cultivars; many ofthe small fruits are set on each nodeand on the laterals. Yields can becompact (10 harvests or less) or con-tinuous (more than 30 harvests), de-pending on season. Beit Alpha culti-vars grow well under extreme envi-

ronmental conditions, especially hightemperature (90 to 95 C). Thesecucumbers appear to be sensitive tolow temperatures (below 50 F) espe-

cially in the seedling stage.Several production and post har-

vest trials have been conducted bythe University of Florida, both inGainesville and Live Oak, in the pastfive years. Several cultivars haveproduced very high marketableyields, equivalent to, or higher than

standard European cucumber types.Most Beit Alpha types produce fruits15 to 20 cm in length and specific sizeis important in certain ethnic mar-kets. A primary production chal-lenge has been powdery mildew.Most early released cultivars werevery susceptible to the disease; how-ever, newer releases appear to haveincreased tolerance. As many as 18

Figure 3 Bibb lettuce grown in NFTchannels.

Figure 2 Cluster tomato productionin perlite.

Figure 4 Leaf lettuce produced in asmall floating system.


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systems and timing technologies forthese markets can be very challeng-ing. Trials at the North Florida Re-search and Education Center Su-wannee Valley, with vertical systems(Verti-Gro) for several specialty

leafy green vegetables (Figure 5),have been encouraging for growersto meet this challenge.

HerbsIn the last decade, there has been a

dramatic increase in greenhouseherb production in Florida, from vir-tually none in 1991 to nearly 17 acresin 2001. Herbs now rank third ingreenhouse food crops, accountingfor 18% of the states greenhouseacreage. The major herb now grownin Florida greenhouses is basil, how-ever, dozens of other herbs are beinggrown also.

Herbs have a long history of useby humans. In ancient times, as wellas today, herbs have been used formedicinal, cosmetic, and culinarypurposes. Herb and spice consump-tion in the U. S. doubled between1965 and 1985, from 1 to 2 lbs percapita according to a report by S.Stapleton UF, IFAS, NFREC SV in

2001. The volume of basil and oreg-ano sold in the U. S. increased 187%and 75%, respectively, from 1981 to1991. Total sales value of fresh-cutherbs produced in U. S. greenhouseswas $30,995,000 accounting fornearly 14% of all greenhouse foodcrops sales in 1998. Fresh-cut herbsaccounted for $647,000 in sales offood crops from Florida greenhouses


fresh cut in containers filled withsoilless media and also grown forwhole-plant sales in NFT systems(Figure 6).

Other successful trials for herbproduction have included mints and

chives (Figure 7) in lay-flat bagsfilled with perlite. As with mostgreenhouse specialty crops, growersmust become especially knowledge-able about the differences in herbpricing, packaging, post harvest han-dling, and marketing for success andprofit.

`Galia Type Muskmelon`Galia muskmelon (Cucumis melo

L. Reticulatus group) could becomeanother hydroponic crop favorite.

The `Galia melon is a green-fleshed muskmelon with a golden-yellow netted rind at maturity.`Galia fruits have a unique aromaand sweet flavor, and show promiseas a specialty melon. Grown hydro-ponically in a protected-ag structure,`Galia fruit (Figure 8) quality sur-passes the quality of field-grown or-ange muskmelons because of its bold

in 1998. The demand for fresh-cutherbs is expected in increase in partdue to health-conscious consumersand increasing consumption of ethniccuisine.

Greenhouse production of herbs

offers several market advantages in-cluding more rapid plant growth,wintertime production when marketprices are highest, and a clean prod-uct. The clean, hydroponic productmay not require washing prior toshipment, which contributes to alonger shelf-life and a high qualityappearance. Quality was rated as themost important factor in selectingherb suppliers by 78% of herb buyersresponding to a national survey.

Studies by S. Stapleton and R. Ho-chmuth were conducted to examinemarketable yield of selected fresh-cutherbs from fall through spring in avertical hydroponic greenhouse pro-duction system (Verti-Gro, LadyLake, FL) in north central Florida.Herbs included in the trial were: aru-gula (Eruca vesicaria), basil (Ocimumbasilicum) purple basil (Ocimum basili-cum), chervil (Anthriscus cerefolium),dill (Anethum graveolens), lemon balm(Melissa officinalis), sweet marjoram

(Origanum majorana), oregano(Origanum vulgare), parsley(Petroselinum crispum), Italian (flatleaf) parsley (Petroselinum crispum)sage (Salvia officinalis), and thyme(Thymus vulgaris). The best overallperformers in the Verti-Gro systemshave included: basil, oregano, pars-ley, sweet marjoram, and thyme.Basil is also commonly grown for

Figure 5 Herbs, edible flowers andspecialty greens in VertiGro towers.

Figure 6 NFT basil production.Figure 7 Hydroponic chives in per-lite bags.

Figure 8 Greenhouse Galia mel-ons.


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aroma and high sugar content, lead-ing to higher market value.

The Florida vegetable industry isfacing many challenges, includingthe loss of the soil fumigant methylbromide in 2005; increased regula-tions on water, fertilizer, and pesti-cide use; increased urbanization andloss of production land in southernFlorida; challenges from weather,including freezes, wind, and rain;and increased regional and globalmarket competition. Not only arealternative growing methodsneeded, including protected agricul-ture in non-traditional growing re-gions of Florida, but also new spe-cialty commodities, such as `Galiamelon, may be what Florida growersneed to stay competitive. In Europe,`Galia melons are in high demandand well known for their superior

quality and high soluble solids; fur-thermore, `Galia has become anidentifiable trade name.

Research conducted by Universityof Florida, Protected Ag Project inGainesville by graduate student,

Juan Rodriquez has evaluated sev-eral aspects of `Galia muskmelonproduction, including: cultivar selec-tion, nutrient management, soilless


Cantliffe, Dept. of Horticultural Sci-ences, indicated plant densities of 17plants/m2is required for break-evenyields. Viable systems to accomplishthis include vertical systems or

moveable trough systems that aresuspended above ground level, lend-ing ease of harvest. Plant densitieswith these systems can be five timesgreater than the plant densities intypical field culture. Challenges alsoincrease in the greenhouse, however,in the area of pest management, es-pecially for botrytis and spider mites.If these issues are resolved and ifproblems with soil fumigation andlabor in field production persist,greenhouse acreage of strawberrycould see rapid increases.

Other Miscellaneous AlternativeCrops

As the markets demand highlyspecialized crops, greenhouse pro-ducers may consider meeting theseneeds. Often the market demandscrops in condition or at a timing that

media, disease and insect manage-ment, pruning methods, and pollina-tion. Disease and insect management

can be especially challenging ingreenhouse muskmelons grown inFlorida. Prices for imported `Galiamelons have varied from $1 to $3.50per lb in 1999-2000. Currently this isa very specialized niche market inFlorida; however, as production chal-lenges are solved and consumersacceptance increases, `Galia musk-melon may become a popular alter-native greenhouse crop in the future.

StrawberryThe Florida greenhouse strawberry

(Figure 9) is a product that has cap-tured the imagination of many overthe past dozen years. Several aspectsof this crop makes the greenhouseconcept appealing, including: highfruit values, protection from freezingtemperatures, high value in off theseason, difficulty with labor harvest-ing (low crop culture), and challengesof finding suitable alternatives to thesoil fumigant, methyl bromide. Even

with high interest in greenhouse pro-duction of strawberry, commercialadoption remains relatively low inFlorida (about one acre). Recent UFresearch has focused on new produc-tion and pest management systemsfor greenhouse strawberry (Figure10). High plant populations are re-quired for profits. UF research con-ducted by Ashwin Paranjpe and Dan

Figure 10 Alternative greenhousestrawberry production system, UF/IFAS Horticultural Sciences Depart-ment, Protected Agriculture Center,Gainesville.

Figure 9 Greenhouse strawberries

in VertiGro towers with owner TimCarpenter.

Figure 11 Specialty peppers grownin a greenhouse. Photo: WandaLaughlin

Figure 12 Cut-flower zinnia.Photo: Laurie Osborne


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can only be met by the utilizing theprotection of a greenhouse. Othercrops being grown on a small com-mercial basis in Florida include:fresh-cut flowers, edible flowers,specialty peppers (Figure 11) and

tomatoes, and eggplant.The efforts at the North FloridaResearch and Educational Center Suwannee Valley have been success-ful in refining a production systemfor cut-flowers similar to that usedfor vegetables. This project evolvedout of interest in greenhouse tomatogrowers to produce other more prof-itable greenhouse crops. The cropsthat have the most potential arethose specialty cut flowers that aredifficult to ship from other largerproduction areas. These includeflowers such as zinnia (Figure 12 andFigure 13) , snap dragon, sunflower,delphinium, and lisianthus (Figure14). Small growers in North Floridahave been successful in producingtop quality flowers for local sales.Expansion of these local marketingefforts depends upon growers beingable to grow several different speciesto maximize the number of specialtycuts to be sold on a weekly basis. In

addition, flowers that continue tobranch and produce more cuts onthe same plant over a long period oftime have shown to be the most prof-itable candidates. Zinnia and snapdragon, for instance, have this typeof growth habit.

Edible flowers can be good com-panion crops for local greenhouseproducers, especially herb produc-

http://www.hos.ufl.edu/ProtectedAg/

Robert C. Hochmuth, Multi County ExtensionAgent, North Florida Research and EducationCenter Suwannee Valley, Live Oak, FL 32060

ers. Although the demand is small,the value is high and the opportunityto provide high quality edible flow-ers to chefs in urban Florida restau-rants is great. Vertical production(Verti-Gro) of these has been highly

successful in trials at the North Flor-ida Research & Education Center Suwannee Valley. Edible varieties ofnasturtium (Figure 15), viola, stock,and marigold have all been success-fully produced in trials at Live Oak.

Specialty varieties of pepper, to-mato, and eggplant also can providealternative crop opportunities forgreenhouse growers, especially forlocal markets. In some cases, produc-tion of specialized varieties of manycrops in the field can be very difficultdue to diseases, insects, or weatherproblems. The greenhouse may cre-ate opportunities to produce highlyspecialized crops, like heirloom to-matoes, off season specialty pepperor tender eggplant varieties. Theseare typically opportunities for smalland specialized greenhouse opera-tions. Many small operations havebeen successful with this diversifica-tion approach by selling directly toconsumers at Farmers Markets or

other retail markets. High qualitygreenhouse tomato, cucumber, orpepper accompanied with lettuce, cutflowers, strawberries, herbs, and spe-cialty leafy green vegetables canmake a great crop mix at a local mar-ket for a small, but talented green-house grower.

For more information on protectedagriculture visit:

Figure 13 Benary Giant ZinniaPhoto: Laurie Osborne

Figure 14 LisianthusPhoto: Laurie Osborne

Figure 15 Nasturtium.

http://vfd.ifas.ufl.edu

http://smallfarms.ifas.ufl.edu

greenhouse production florida

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