Grower’s Guide to Tiny Greens

By Dr. Lynette Morgan

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callyfortheirdistinctiveflavorwhichisoftenmore subtle and delicate than the matureplant.Other̀ spicyorpungent’greensmaybeusedincombinationwiththelesserflavoredtypesinsaladmixesorusedontheirownasanimportantconstituentofadish.

ArugulaArugulaisoneofthemostpopularmicro-greens due to its distinctive tangy, nuttyalmostastringentflavorwhichiswelldevel-opedineventinyseedlings.

BasilBothgreenvarietiesofbasilsuchasGenoveseandredtypessuchasDarkOpalareanotherwidelygrownmicroherb.Somelesserknowntypesofbasilsuchaslemon,Thaiandcin-namonbasilarealsogrownasmicrogreensfor specialized markets. Basil microgreensarealsohighlyattractiveandhaveasubtleflavorandaromawhichisnotoverpoweringinsaladmixes.Basilgerminatesandgrowsrapidly in microgreen systems; however ithasahigherheatrequirementthanmanyofthetraditionalgreensandheatingisusuallyrequiredforwinterproduction.

RadishRadishmicrogreenshaveasurprisingflavorandsomevarietiesareashotandpungentasafullymatureradishroot.Thereisalotofdiversityamongsttheradishvarietiesusedfor microgreen production: colors includegreenpinkishredandvividpurpleandthisisoneoftheeasiestgreenstogrow.Radishisusedasacolorspikerorgarnishandthedarker colored typesarehigh invitamins,mineralsandantioxidants.

Flavorful Greens

Some of the flavorful microgreens may come as a surprise to both hydroponic producers and customers. Many commonly available vegetables now have a mini microgreen version which has the same flavor but can be used in more diverse ways.

CarrotCarrot microgreens are light and featherywith a mild carrot flavor and aroma. Car-rotseedismuchslowertogerminatethanmostothermicrogreenswithamuchlongerproductiontimeandtheharvestedproductislightweight.

Celery Celerymicrogreenshaveverybecomepopu-larandareusedalmostlikeaherbforaddingmildflavorindishes,saladmixesandasagarnish.It’sflavorcanbemoderatelystronginevenyoungseedlings.

thespecificationsoftheirmarket,allowingchefstodecidehowmanyleavestheywantontheirmicrogreenproductatharvest.Manyspeciesaresimplygrowntoapredeterminedheight–often2to3inchesbeforeharvesting.Microgeenseedisgrownatahighdensitysothatthedevelopingseedlingsgrowtallandstraightwithatenderalmostblanchedstemandbright,well-developedleaves.

Health-giving Properties of Micro-greensSomemicrogreenspeciesaregrownspecifi-callyfortheirhealthycompoundsandprop-ertiesandthesehavefoundanichemarketwithin thehealth food industry.Themostwellknownoftheseiswheatgrass,whichhasbeengrownformanyyearsasafreshorfrozenhealthsupplementafterjuicing.Wheatgrassisconsideredahighlynutritiousandcleans-ingfoodsourcerichinvitamins,minerals,amino acids, antioxidants and enzymes.Other species such as flax, chia, broccoliandvarietiesofredbrassicaalsohavehealthcompounds.Thedarklycoloredpurple/redvarietiesofradishmicrogreenwhichproduceintensely-coloredyoungleavescontainhighlevelsofantioxidantslinkedtohavinganti-cancerproperties.

Common Microgreens

Shoots and tendrilsPea shoots have been in use as a gourmetsalad item or garnish longer than mostothermicrogreens,howevertheirpopularitycontinuestogrowandother̀ shoots’suchassunflowersarenowalsomakinganappear-ance.Peashootshaveatenderflavorsimilartoyoungsnowpeapodsandalong,white,succulentyetcrunchystemwhichaddsbothtexture and flavor to many dishes. In thepastthesnowpeahasbeengrownforshootproduction,howevertherearenewvarietieshavebeendevelopedfortheproductionofpeatendrils.Peatendrilsarethepartthattheplantusestoattachontosupports;theyarelong,thin,featheryanddecorativewhichmakesthempopularasagarnish.Varietiesofpeaswhichproducelessleafandmoreattractivetendrilshavebeenbredandyieldahigherweightofharvestedproductandwillevenregrowifnotcut too lowatharvest.Cornshoots are another microgreen harvestedatthe2–3inchstagethesetastelikemildfreshsweetcorn.

Spicy GreensSomegreensaregrownfortheirattractiveappearance,textureorcolor,whileothersarehighlysortafterfortheirflavorandaroma.Manyofthemicroherbsaregrownspecifi-

Microgreens: larger than a sprout, smaller than a baby salad leaf — they’re the latest trend to hit the gourmet food world and a diverse crop hydroponic growers are beginning to embrace. Microgreenshaveactuallybeeninproduc-tionforafewyearsnow,althoughvarietyinthepastwas limitedto largelyfreshwheatgrassforjuicing,snowpeashootsandafewothergarnishes.MicrogreensoriginatedinCalifornia where innovative chefs startedusingthemtoincorporatecolor,flavorandtextureintotheirdishes—atrendwhichrap-idlyspreadacrosstheU.S.Nowmicrogreensarebeingproducedcommerciallyinmanycountries and the diversity of productionmethodsandspeciesgrowniseverincreas-ing. Microgreens have many of the healthbenefits of sprouts, most pack a powerfulpunchofflavorfortheirtinysize,andthesedelicate mini plants are springing up ontrendyrestaurantmenusatanexplosiverate.Microgreensappearastoppings,garnishesandflavoringsinsaladsandfeatureinmanyup-market dishes as well as being sold inproducestoresandsupermarkets. What makes microgreens so unique isperhapsthediversityofcropspeciesbeingproducedandthefactthattheyareincrediblywell-suitedtohydroponicproduction.Unlikebabysaladgreensormesclunmixeswhicharecommerciallygrownandmechanicallyharvestedonalargescaleoutdoorsinsoil,microgreensneedcarefulattentiontodetailandpreventionofcontaminationwithgritparticles.Greenhouseorindoorproductionare well-suited for microgreen productionbecauseplantsgrowinsoillessmediawithhighcleanlinessandhygienerequirements. Microgreens are also good for smallerhydroponicgrowerswithlimitedspacelook-ingforaprofitable,fastturn-aroundcropwithdirect sales to customers and restaurants.Theyarealsotheperfectbenchtopcropforgrowingathomeinordertohavefresh,minisalad greens year round. With some basichydroponic technology and a fluorescentgrow lamp, sufficient microgreens can begrownonakitchenbenchtosupplysalads,gar-nishesandsandwichesforthewholefamily.

Defining MicrogreensItcanberatherhardtodefineatexactlywhatstage of growth a particular crop specieswould be called a microgreen. Generally,microgreens are larger than a sprout andhaveproducedatleasttwotrueleavesafterexpansionoftheseedlingleavesorcotyle-dons.Howeversomegrowersharvestthemattheseedlingleafstagewhileotherslettheirmicrogreensdevelopandproduceuptofourtrue leaves.Manyevengrow their crop to

Grower’s Guide to Tiny Greens

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Chives Babychiveleavesarehighlydecorativeandoftenusedtoreplacematurechoppedchiveleaves.Chivesareslowertogerminatethanmany other microgreens and productiontimes are longer. They can be sown at averyhighdensityandtheclumpsharvestedbycuttingatthebasewhentheyreachtherequiredheight.

Broccoli Broccolimicrogreensarerich in thecom-pound sulforaphane, considered to havemanyhealthbenefitsduetoitsanti-cancerandanti-bacterialagents.

CabbageRedcabbageisusedforitsmildcabbageflavorandattractivecolor.Cabbageseedgerminatesrapidlyinmicrogreensystemsandisrelativelyeasytoproduce.Therecanbeproblemswithcaterpillarsingreenhousesatcertaintimesoftheyearandscreensarerequiredtoprevententryofegglayingbutterflies.Mustard and Cress Mustard and cress are perhaps the oldesttypesofmicrogreensgrown.Bothhavebeenproducedasseedlingsforuseinsandwichesandsaladsformanyyears.Mustardandcresshaveasharp,pepperyflavorandareeasytogrowasamicrogreencrop.

WatercressWatercress is a less common microgreenpossiblybecauseof itsslowrateofgrowthfromseed.Watercresshasapepperyflavorandmakesanattractive,brightgreengarnish.Italsohasprovenhealthpropertiesandcon-tainsgoodamountsofvitaminA,C,calciumionandfolateaswellasisothiocyanateswhicharecancer-fightingcompounds.Watercressgrowsextremelywell inNFTandsolutionculturehydroponicsystemsandhasconsider-ablepotentialasamicrogreencrop.

ParsleyFlatleavedparsleyisoneofthemostpopularmicroherbsandcanbegrownatahighdensityandharvestedattheoneortwotrueleafstagedepending on customer requirements. Itsflavorismildbutdistinctiveanditcontainsnoneofthefibrousstemsthatoldermatureparsleycandevelop.

FennelWith a mild aniseed flavor and attractivegreenfeatheryleaf,fennelmicrogreenshavebecome popular with chefs. Fennel seedgerminates readily, although this crop canbepronetoaphidattackinspring.

Chrysanthemums

(ChineseEdibleChrysanthemum)AlsocalledShungiku,thisisaherbusedinorientalcookingandhasbecomeapopularmicrogreen due to its interesting flavor,whichtastessimilartohowchrysanthemumssmell.

CilantroCilantro microgreens are one of the mostpopularminiherbsandcandeveloparea-sonablystrongflavorunderwarmgrowingconditions.Cilantroisawarmseasoncropandneedsat least22 to26degreesC forgermination—conditionssimilartowhat’srequiredbybasilminigreens,makingthemidealtobecroppedtogetherwhereheatingisrequired.

French SorrelSorrellhasaverydistinctive, sharp,acidicandslightly-bitterflavorandcanbeusedasasaladspiker.Oftenmaturesorrelbecomestoointenseoracidic,howeverthemicrogreenversionismilderandlessbitter,althoughcanbeslowgrowingandpreferscoolergrowingconditions.

MintMint is a lesser grown miniherb, possiblybecausemintseedistinyandslowtodevelopinto a small plant. The flavor is mild, yet

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distinctiveandthemicroplantsarehighlyattractive.MintpreferscoolgrowingconditionsandperformswellinNFTandotherhydroponicsystemswhereplentyofmoistureisprovided.Mintmicrogreensneedtogrownundershadeinsummerwiththenutrientsolutiontemperaturemonitoredandchilledtopreventitfrombecomingtoowarmforgoodmintgerminationandproduction.

DillDillmicrogreenshavebecomepopularinfishdishes,oftenreplacingmaturechoppeddill.Theflavorisverymild,butthefoliageissimi-lartofennelinappearance—featheryandattractive,althoughverylightweight.

ShishoRed/purpleandgreenshisho(perilla)—sometimesreferredtoastheSushiherbusedinJapanesecuisine—hasbecomemorepopularasasaladgreen.Perillaisanattractiveandwell-flavoredmicrogreenwithleavesresemblinganornamentalcoleus.It’sachallengingmicrogreentogrowbecausetheseedneedstoberelativelyfreshtogerminatewellandalsobenefitsfromstratificationat5degreesCundermoistconditionsbeforesowing.Perillaseedalsoneedslighttogerminateandshouldbelightlysownintothetopofthegrowingmediaormats.

Tender Greens

While lettuce varieties often make up the bulk of mesclun or baby leaf salad mixes, the tender or succulent species used for microgreen produc-tion are quite diverse and includes a range of leaf sizes, shapes, colors and textures.

SpinachEnglishspinachhasadarkgreenleafandverymildflavor.Spinachseedcanhavealowgerminationrate,particularlyifconditionsbecomeoverlywarm.Optimumtemperatures forgerminationare16to22degreesC.Underhightemperatures,alargeproportionoftheseedmayfailtogerminateandthiscanthenrotinthemicrogreensystemandcausedisease.Spinachisacoolseasoncropwhichbenefitsfromsummershadingandnutrientsolutionchilling.

BeetBeettypessuchasBullsBloodisprimarilygrownforitsintenseredcoloronevenveryyoungseedlings.

TatsoiTatsoihasaroundedleafandthickwhitepetioleswithacrisptextureandhasarapidgerminationandgrowthrate.Thisisahighlyproductivemicrogreenforhydroponicsystemsandhasfewproblems.

MitzunaMizunahasanattractivelightgreenserratedleafandisoneofthefastestandmostpro-ductivemicrogreenstogrow.Germinationisrapidandthecropusuallyhasfewdiseaseproblems.Mitzunahasaverymildmustardflavorandawiderangeofuses.

AmaranthRedamaranthisgrownprimarilyforitsdeepcolorandattractive leaves,althoughgreentypeswithpinkstemsalsoexist.

ChardChardisavailableinarangeofcolorsinclud-ingyellow,pink,redandgreenandithasamildspinachtaste.SeedgerminatesreadilyalthoughChardismoreofacoolerseasoncropwithaslowergrowthratethanlettuce.

KaleMicrogreen kale produces succulent andtenderleaveswhicharefinelycutandalmostblue-greenincolor.Anothercoolerseasongreen,itscolorbecomespalerunderwarmgrowingconditions.

MacheAlsocalledcornsaladorlamb’slettuce,macheproducesroundedleaveswithalettuce-likegrowth.It’sacommoningredientinbabyleafmixesanditsmicrogreenversionhasmanyusesandcanbeharvestedfromthetwotofourleafstage.

LettuceLettucemicrogreensarerelativelyeasytopro-duceinmostsystems,howevergermination

problemscanoccuroncetemperaturesreach26degreesCorhigherwithseedgoingintosecondarydormancy.Shadingandchillingmaybenecessary inhot summerclimatesforhighqualitymicrogreenproductionoflettuce.

This is just a selection of microgreen types being grown commercially using hydroponic methods, there are many other varieties of greens and the list continues to grow.

Production of Microgreens Seed Whereverpossible,useseedthathasbeenpackagedandproducedspecificallyforsproutor microgreen production. This usuallymeans the seedhasavery lowpercentageof `foreignmatter’orcontamination fromotherspeciesandiscleanandhighquality.Organically-produced seed is available forsomecommonmicrogreenspecies,althoughthecostofthiscanbealittlehigherthannonorganicseedsources.Seedtreatedwithmanyfungicide compounds should be avoidedbecause this poses a contamination risk.Peasandspinacharecropswhichoftenhavefungicide-treated seed, so growers shouldcheck this before purchasing. Microgreenseedisusuallypurchasedbythepoundorkilogramandcanbekeptstoredinairtightcontainersuntiluse. Somemicrogreenvarietieshaveseedwhichis`mucilaginous’meaningthatoncewettedup,theseedformsathick,gelatin-likelayerwhichholdsmoisture.Cressisoneexampleofmucilaginousseedandtheseseedtypesshouldnotbepresoakedbeforesowing. Larger seeds such as wheatgrass, cornandpeasmaybepresoakedinwarmwater

for24hoursbeforesowing,althoughnotallgrowerscarryoutthisadditionalstep.Somestudiesreportthatmatricprimingadvancesthegerminationofcertainmicrogreenspeciessuchasbeet,chard,amaranth,radishandkale,withadvancementinseedlingemergenceinsomegreens. Whensowingintolongtraysystems,evendistributionofseedisimportantandoftenseed shakers are used to assist with thisprocess.Agivenweightof seed shouldbesownintoeachtrayorareatogivethecorrectdensityandthisvariesforeachspeciesbeinggrown.Manycommercialseedsuppliersgiverecommendationsforsowingdensityfordif-ferentvarietiesofmicrogreens,althoughthismayneedtobeadjustedifthecropisgoingtobeharvestedalittlelargerorsmallerthanusual. Aftersowingintothepredampenedmediaormats, theseedmaybemisted intermit-tently in some systems. Others rely onregularfloodanddraincyclesorirrigationsupplied throughNFT-typechannelsuntilgerminationhasoccurredandtheseedlingshaveanchoredthemselveswithayoungrootsystem.

Equipment and Systems There are a huge range of systems andequipmentusedfortheproductionofmicro-greens.Manygrowersfacedwitharapidlyestablishingnewnichemarket,simplymodi-fiedtheirproductiontechniquesofleaflettuceandmesclungreensorherbstoincorporatethesmallerminigreens.Commercialgrowerssettingupthesedaysnowhaveequipmentspecifically-designed for this crop such asmodified-wideNFTtypetrays,tieredsystemsandvariousfloodanddraintables.Smallergrowersoftenuseshallownurserytrayslinedwithmatsormediaintowhichthemicro-greenseedissownwithoverheadirrigationor flood and drain methods for watering.The microgreen seed requires some formofsupporttoholdandwickmoisturewhileat the same time preventing water-loggedconditionsthatpreventoxygenreachingthegerminatingseed.Microgreengrowershaveutilizedmaterialsasdiverseaspapertowels,burlapsheets,perlite,vermiculite,rockwooland specialized microgreen mats for thispurpose, although loose media can createproblemswithgritparticlescontaminatingtheharvestedproduct. Themajorityofmicrogreenproducersuseclimate-controlled greenhouses for year-roundproduction.However,inhumidtropi-calareas,productionofthesecanbelimitedbytemperature,andsincemicrogreenscanbegrowninarelativelysmallarea,refriger-atedshippingcontainersandchillerrooms

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withartificiallightingarebeingusedfor production. Lettuce and sproutgrowersintropicalregionsoftenusechilledroomstogerminateseedwhichwouldotherwisebedifficulttosproutoutdoorsinagreenhousesituationduetoextremetemperatures. Microgreenscanbegrownthroughtoharvestinthesetemperature-con-trolled rooms, usually in a tiered orshelf system with fluorescent tubesused as grow lamps. In this type ofsystem, the freshly-sown trays areinitiallygerminatedonthelowertiersofshelvesaslightisnotnecessarydur-ingthisstage.Oncegerminationhasoccurred, the trays are then shiftedupontotheshelveswithlightingfortheyoungleavestodevelopfullcolor-ation.Thetemperatureandhumidityiscontrolledtooptimallevelsforthetypeofmicrogreensorsproutsbeingproduced. With this system, micro-greens can be produced on-site andharvestedimmediatelybeforeuse.Useofrefrigeratedshippingcontainersforfresh microgreens on-site in often remotetropicalareasforresorts,restaurantsandlocalsupplymeanfreshgreenscanbereadilyavail-ableinashort-timespaninanenvironmentwhereoutdoorgrownvegetablesarescarceorveryexpensive. Becausemicrogreensarehighlyproductivefortheamountofspacetheytakeup,theycouldalsobeviableforindoorgrowersorwithmodificationofwarehousespace,garagesandother areas. Lighting is required for thesegreens.However,sincetheyaretechnicallynotgrownpasttheseedlingstage,lowerlightlevelsarerequiredthanifamatureorfruitingcropwasbeingproduced.FluorescentgrowtubesandT5lightingsystemincorporated

intoshelvedgrowingracks,alongwithsomegoodairflowandventilationoverthetraystohelpremovehumidity,cangiveahighly-productiveindoorgrowingsystemforsmallhydroponicgrowers.

Watering and Nutrition Microgreensaredifferentfromsproutsintheir nutritional requirements and requirea dilute nutrient solution to be applied tomaintain foliage quality and growth rates.Sprouts are typically soaked and mistedwithonlywaterbecause the seedcontainssufficient reserves for the short period oftimethesearegrown.Microgreenshoweveraregrowntothepointofdevelopingtheirfirst true leavesorsometimeseven longer,

and thereforeneedsomedilutionnutrientsolution to support this process. Initially,microgreen seed needs to be germinatedin water — any salts applied at this stagecancausegerminationproblems.Oncethecotyledons(seedlingleaves)arevisibleandstartingtodevelopchlorophyll,theseedlingwillhaveexhaustedthereservescontainedin the seed. At this stage, the young plantisstartingtophotosynthesizeandproduceitsownassimilate,andnutrientionswillbeabsorbedbytherootsystem. Ageneralpurposevegetativeorseedlingnutrientformulationisusuallysufficientformicrogreenproduction,howevercommercialgrowersshouldcarryoutaninitialwatersup-plyanalysistocheckfornaturally-occurring

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mineralsandhavetheirformulationadjustedforthepresenceofthese.EClevelsaretypi-callyrunatseedlingstrengthformicrogreens,although they may be adjusted for seasoninasimilarwaytolettuceandherbcrops.ThereissomescopetomanipulategrowthofmicrogreenswithuseofEC.HigherECcanbeusedtoboostcolordevelopmentinredtypesduringlowwinterlightifnecessary.ControlofECwillalsoaffectshelflifeofcutmicrogreens.Seedlingsgrownonverydilutesolutions can develop `softer’ tissue and ahigherrateofwaterlosspostharvestversesthoseplantsreceivingahigherEC.pHlevelsformicrogreensarethesameasthoseusedforproductionofthematureplant–around5.8formostspecies.

Hygiene Considerations Justaswithsproutproduction,therearefood safely requirements for microgreenproduction. Various fungal pathogens candevelopandgrowonsproutingseed,particu-larlyunderthehumidconditionsandhighdensitiesmicrogreensaregrownatandthesecan pose a contamination risk. Generally,high-qualityviable seedsown intoacleansystematthecorrecttemperatureforgermi-nationandthecorrectmoisturelevels,willgerminaterapidlywithfewproblems.Diseaseoutbreaksaremorecommonwhereoldseedmaybeusedorwheretemperaturesareeithertoohotorcoldforrapidgermination.Overwateringalsopossesariskasseedmaybegintorotbeforegerminationcanoccur. The water supply needs to be of highquality—watercancarryhumanandplantpathogenswhichmaycontaminateacrop,althoughamunicipalwatersupplyistreatedtopreventthisrisk.Otherhealthandsafetyconcernsaresimilarforallhydroponicopera-tions:birdsandrodentscancarrydiseaseintothecroppingareaandworkersshouldwashtheirhandsthoroughlyorweargloveswhenharvestingandpackagingtheproduct. Food baths at doors of greenhouse andpackingareasalsohelpkeeptheseareascleanand disease-free. There are also concernsandmoreregulationsthesedaysrelatingtofoodsafelywithfreshproduce.Hydroponicgrowersshouldbeawareoftheproceduresandguidelinestheyneedtofollow.

Pests and Disease While microgreens are grown rapidlyandharvestedyoung,theycanstillbecomeinfectedwithdiseaseandinfestedwithpests.Luckilyifaseverepestordiseaseoutbreakdoesoccur,thecropcanberemovedandtheareacleanedandreplacedwithanewcropreadyforharvestinjustafewweeks.How-ever, persistent pest and disease problems

have been known to occur in commercialmicrogreen crops just as they can in anyhydroponicoperation.Aphidsinparticularseemtosavor tendermicrogreens,butaremostlyaproblematcertaintimesoftheyearwhen winged adults are flying and maketheirwayintotheproductionarea.Inmostmicrogreenoperationsthereareusuallycropsatdifferentdevelopmentstagespresentatanyonetimesoitispossibleforapestinfestationtocarryover frommorematuregreens torecentlygerminatedones,althoughtherapidcropturn-arounddoespresentwidespreadbreedingwithmanyinsectpests. Diseases can become an issue wheregrowing conditions are particularly warmandhumid.Becauseof thedensitymicro-greens are grown, at outbreak of dampingoffpathogenssuchaspythiumcanbepar-ticularlyseriousandspreadatarapidrate.With this sortofproblem,diseasedplantsarebestremovedandtheoutbreakisolatedas control with fungicides can be difficultwithsuchatendercrop.Preventionoffun-galandbacterialoutbreakisimportantandusingsterilizedgrowingmedia/mats,cleanwater,goodhygieneandcleaningofgrowingsurfacesaftereachcrop—combinedwithhumidity control and good air flow — allassistwithpreventionofdiseaseattack.

Harvesting Microgreensareharvestedandpackagedintoclamshellsorotherbulkpacksandaretypicallycutrightatthebaseofplantstem,justabovethesurfaceofthegrowingmediaormat.Cuttingheightisimportantashighqualitymicrogreensneedagood,cleanpor-tionofstembelowtheleaves,butshouldnotbecutsolowastoriskcontaminationwiththe growing media or material the seedsweresown into.Thisbecomesparticularly

importantifaloose,granularmediahasbeenusedforproductionasparticlescaneasilybepickedupduringtheharvestingprocessandcontaminatetheproduct. During warm growing weather, micro-greens,justaswithherbsandlettuce,arebestharvestedearlyinthedaywhenthefoliageiscoolestandmostturgid.Thiswillprolongtheshelflifeofthepackagedproduct.Cuttingshouldbecarriedoutwithasharpknifeorscissorstopreventexcessivetissuebruisingandcrushingofthestemswhichalsoreduceproductshelflife.Becausemicrogreensaresotenderatthisstage,harvestersneedtotakeparticularcarenottocrushthedelicatestemsorfoliageduringthisprocess.Somespeciesaremoredifficulttoharvestthanothersduetosoft,lightorfeatheringfoliage,dill,fennelandcressaresomeofthesoftervarietiesthatneedcarefulhandling. Formicrogreensbeingshippedwhilestillgrowing in trays or cells, the handling issomewhateasier.Thesecanbestoredunderrefrigerationformostspecies,whichwillslowgrowthandrespirationbythefoliagesothatthe plants become almost dormant, whilestillbeingabletotakeupsufficientmoisturefromthe rootzone topreventwiltinganddesiccation.

Marketing and Packaging Mostmicrogreensaresoldeithercutandpackagedintovarioussizedclamshells—two,four or eight ounce sizes — or as a livingproductincellpacksortrayswhichcanbecutjustbeforeserving.Shipmentwhilestillgrowingintraysorpacksensuresmaximumshelflifeandthecustomercandecideatwhatsizetheywanttoharvestandusethediffer-ent microgreen species. Many microgreenproducers supply their markets with bothindividual species packs and mixtures of

greens, ready to use. Examples of variousmicrogreen mix products include `spicyAsian’mixesand̀ Mediterraneanmixes’,alsorainbowcoloredandherbmixesareavail-ablewithsomegrowerscreatingcustomizedmicrogreenmixesforcustomers. Microgreens are young and tender andthereforehaveahighrateofrespirationandpotentiallyashortshelflifeifnotstoredandhandledcorrectly.Clamshellpackaginghelpsretainmoisturearoundthefoliageandpro-tectthedelicateyoungtissuefrombruisinganddamage. If storedunder refrigeration,microgreens should have a shelf life of atleastoneweek.However,basilmicrogreensneedcarefulhandlingbecausebasilisproneto chilling damage at temperatures below40 degrees C with foliage discoloring andblackeningresultingfromcoolstorage.Basilmicrogreensneedthesamestoragecondi-tionsasmaturecutbasilherbproductions,attemperaturesabove40degreesF.

Where to Next? While microgreens are still considered anichemarket, there isgrowingdemandforsalesthroughstandardproduceoutletssuchassupermarkets,organicoutletsandproducestoreswhichwillseedemandincreaserapidly.Microgreens are likely to take a portion oftheexistingsproutmarketaswellaspickup

newcustomers lookingforahigh-endgourmetitem. There also existspotentialwithinthecer-tified organic marketwithhydroponicorganicgrowersalreadyinexis-tence. Hydroponic micro-greens are a cropwell-suited to smallhydroponic growerssupplying local mar-kets. Although there is

a degree of skill required in growing theseseedlingsathighdensitiesandmaintainingpostharvestquality, thewiderangeofspe-cies,diversityofusesandgrowingpopularitymakesthemagreatpropositionforhydroponicgrowers.

Resources: Further information and sources of microgreen suppliesCommercial multipurpose tray — AmericanHydroponics,www.amhydro.comMicrogreen grow mats — Sure To Grow, www.suretogrow.comMicrogreen seed — Johnny Seeds, www.john-nyseeds.com

Microgreen growers Web sites:GreenCuisineGourmetMicrogreens,http://chef-sgreens.comOHproduce&organicallycertifiedhydroponicmicrogreen production http://ohproduce.net/index.htm

References:Advancing greenhouse establishment of radish, kale and amaranth microgreens through seed treatments.J S Lee, W G Pill, 2005. Journal of the KoreanSocietyForHorticulturalScience.Volume46(6),p363-368Seed treatments to advance greenhouse establishment of beet and chard microgreens.JSLee,WGPill,BBCob,MOlszewski,2004.JournalofHorticulturalScienceandBiotechnologyVolume70no4page565–570.http://www.viamagazine.com/top_stories/articles/microgreens02.asp