THE COMMERCIAL GREENHOUSE GROWER • MAY 2013 www.actpub.co.uk

1TULIPS •

TULIPS are big businessin the Netherlands, andnot just for bulbs for

export, but also for cutflowers, and the recently-heldKom in de Kas weekendopen days, provided aunique opportunity to take afirst-hand peek at the state-of-the-art facility and family-run business of MaatschapKreuk.Located near Andijk, to the

north of Amsterdam, and runby Niels Kreuk and hisparents Koos and Nel, theirexisting 3,000sq.m.greenhouse had become toosmall.In searching for a new one,

the family was keen to createa multilayer system, the aimbeing to promote theflowering of the tulips, obtaingreater elongation during thegrowth phase using LEDs,improve the internal logistics,and above all make energysavings.Although the resulting new

building covers just1,500sq.m., having threelayers of plants, the bottomlayer lit by LEDs, effectivelyincreases the cultivated areato 3,400sq.m.It is difficult to argue with the

claim that this is the world’smost modern tulipgreenhouse. Installed in2011, in the two years thatfollowed the intelligent layouthas allowed the family toboost production from 6 tonearly 10 million stems ayear, many of which aredestined for the UK andScandinavia.The decision to build a

state-of-the-art structure wastaken in November 2010. Early 2011, trials were

conducted where tulips wereforced in a non-daylight roomusing different combinationsof LED light and sunlight.There were lots of issues to

resolve. For example, in theprojected structure the toplayer would be undersunlight, while the bottomlayer would be under LEDlights. Also, there are manydifferent tulip varieties, all ofwhich react differently underLED lights.The small amount of sunlight

that the middle and bottomlayers would receive at theedges was also taken inaccount.Plant specialists from Philips

and installation company Vander Laan were closelyinvolved in developing theperfect light recipe and theoptimal set-up of the newgreenhouse.Work to erect the new three-

tier structure, which was builtby Zwirs-Knijnenburg, tookplace between the end of theindoor production in April2011, ready in time to beused for the 2012 growingseason. It was a time whenNiels role temporarilychanged from being a growerto a mechanic.Under the supervision of

Philips, LED armatures wereinstalled by Van der Laan inthe bottom layer.Starting in December and

finishing in April, the cutflower tulip process startselsewhere at the extensivepremises with bulbs plantedin plastic trays, each onecontaining around 130 bulbs.For the next two weeks, the7,000 bulbs are stored ineach of the two cold cellsand deluged with a daily

Multi-layer growing and LED technology features prominently at the Dutch family-ownedKreuk nursery. Steven Vale takes a closer look inside what is believed to be the world’smost modern tulip greenhouse.

Multi-layer tulips

Containers are moved around the house and to the threegrowing levels by a system devised by Van Zaal.

one-hour dose of water.After two weeks, the doors

are opened and the traysmanually stacked ontocontainers. This is anotherarea that could bemechanised, but the costsdo not currently justify thisextra step.

Impressive buildingWhen full, each containertravels to the ‘piéce derésistance’ of the nursery –the newly-developedmultilayer growing systemthat really does have to be

seen to be believed.Niels was looking for a

flexible system, and hadplenty of ideas for internallogistics, which were thenconverted into practice byVan Zaal.This Dutch company has

plenty of experience withmultilayer growing systems,but this was the first projectwith tulips.The solution was to get a

computer-operated roboticsystem to move allcontainers in the three-layers.Each row contains 11

2 • TULIPS

www.actpub.co.uk THE COMMERCIAL GREENHOUSE GROWER • MAY 2013

containers (around 25,000tulips).Travelling along two tracks in

the central aisle, the liftsystem quickly movescontainers into position on

both sides of thegreenhouse.My visit took place towards

the end of the season, so notall three layers were full.However, from December

until the end of March, thebuilding is crammed withtulips.When a container from the

cold cell is brought into thenew greenhouse it spends

nearly a week acclimatisingat the second (unlit) level.This is followed by a week at

the bottom of thegreenhouse, after which thecontainer is elevated to the

Each tray is filled with 3.5lit of water a day. 1.5lit remainsin the bottom of each tray. The remaining 2lit is drainedand recycled.

Air ducts provide an ideal solution to heat or cool thebottom and second layers.

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THE COMMERCIAL GREENHOUSE GROWER • MAY 2013 www.actpub.co.uk

3TULIPS •

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top of the structure for onefinal week. Finally, when thebulbs start budding they arereturned to the bottom layeron one side of the house inwhat is internally dubbed thewaiting layer.Depending on weather, 5-6

weeks after planting, thebulbs are then ready to besent back into the existingand adjacent 3,000sq.m.greenhouse for harvesting.

Water and heatingMoving the containers is justone part of the system. Thegrowing bulbs also need tobe irrigated. Thecomputerised ebb and floodirrigation system wasinstalled by Ateco, and atechnique that deluges eachcontainer at least once a dayfor six minutes with freshwater.Each tray is filled with 3lit of

water, which then slowlydrains to leave a small 1.5litlayer of water in each tray.The excess 2lit is recycledand disinfected using UVlight.The best way to heat the

new greenhouse, and tokeep this as close aspossible to 16.5 degrees C,also needed careful planning.In the end, the decision wastaken to use low temperatureboilers.In practice, they tend to heat

water to a temperature from40 to 50 degrees C, and themaximum temperature theboiler operates to is 50-60degrees C. Previously, theyuse to heat their water to 90degrees C.While the top plant layer is

warmed using standardheating pipes, the bottomtwo tiers are heated using airducts, which run the full

Once the containers leave the new multilayer greenhousethe plants are pulled from the trays and placed onto aconveyor belt.

length of the building.In the capable hands of Van

Zaal, and using climatecontrol computers fromHoogendoorn GrowthManagement, the system

provides them with thepossibility to suck in outsideair to alter moisture levels. The heating and cooling,

and irrigation systems areindeed state-of-the-art.

www.actpub.co.uk THE COMMERCIAL GREENHOUSE GROWER • MAY 2013

However, the LED lights tendto enjoy most of the attentionat this nursery.The lowest of the three

layers is fitted with PhilipsGreenPower LED productionmodules, which emit deep-red and blue light.“This combination was

selected because the redlight provides excellentgrowth for the tulips while theblue light has a positiveinfluence on plant growth,producing a better stemlength,” explains Niels.The blue lights are coated

with phosphate which, to thenaked eye, gives the

appearance of white light.This is important because ifthe lights were blue and redthen it would be veryunpleasant for staff to workin the building.On one side of the central

passageway the two stringsof LEDs generate a light levelof 18 mmols/m. On theother, in the waiting bedarea, light levels areincreased to 27mmols/musing three LED strings,simply because fully grownplants need more light.Niels is impressed by the

results of the LEDs whencompared to fluorescentlighting.“The operating costs/sq.m.

are lower because LEDshave a much longer lifespanthan a fluorescent solutionand therefore needs less re-lamping. This in turn resultsin lower labour costs.”He says LEDs also lead to a

tremendous difference inenergy costs. One 35-wattLED module replaces thenormal situation with twofluorescent tubes of 58 wattseach.“This represents an

electricity saving of 65%,” headds. “They also have a

positive effect on the crop,the tulips have a deepergreen colour and greaterelongation.”In fact, while the use of

LEDs leads to a better qualityproduct, it is the overallenergy saving that is theother big benefit of themultilayer system.Niels reckons that while he

produced an extra 1.8 timesmore tulips last year, he used20% less gas.“Overall, I reckon the energy

saving is in the region of 30%because of the use ofelectricity for lighting,” headds.The amount of manual work

has been reduced to aminimum at this nursery. Theonly job that needs to bedone in the multilayergreenhouse is to pull off theouter skins as the bulb startsto grow (a task that couldalso be automated). If theydo not do this then it couldstick to the bulb preventingthe stem from growing.

New bunching machinePulling the bulbs out of thetrays and placing them ontoa conveyor belt remains a

Niels Kreuk (picturedabove) reckons the newmultilayer greenhouse isallowing him to increasestem quality, boostproduction, and make greatenergy savings.

Made by Potveer Machines,the newly-installed QualityBuncher handles anaverage of 1,000 to 1,200bunches per hour (topright).

4 • TULIPS

manual affair, but in thesorting and packingdepartment, the tulips passonto another brand newmachine.Installed by Potveer

Machines, Niels describesthe Quality Buncher as anaffordable way to makemajor labour costs savings,the early results pointing toan average capacity of 1,000to 1,200 bunches per hour,and at peak capacity asmany as 1,400 during thesame hour.By the time this issue

appears, then the multilayergreenhouse will have beenshut down for the summer,the focus switching to thecompany’s 17ha productionsite on heavy clay land in theFlevoland.Working with 15 different

cultivars, the grower tries tobe self-sufficient in tulips.Once the stems have beenremoved, the bulbs from thecut flower process will beplanted in the ground. It willbe another two years beforethey return to the multi-layergreenhouse. ◆