winter spinach production in high-tunnels, 2014-2016 · winter spinach production in high-tunnels,...

NH Agricultural Experiment Station - COLLEGE OF LIFE SCIENCES & AGRICULTURE

http://extension.unh.edu/Agriculture http://www.colsa.unh.edu/aes/

WinterSpinachProductioninHigh-Tunnels,2014-2016ByKaitlynOrde&BeckySideman,UNHExtension

ResearchassistancefromConnorEatonandtechnicalsupportbyTaliaLevy.

Written:June2016

Background&ObjectivesSpinachisasuitablecropforwinterproductioninNewHampshireduetoitsabilitytocontinue

producingsaleableleavesatverylow-temperatures.Falltransplantsintohightunnelscanresult

inwinter-longharvestsandsignificantspringyields,providinganavenueforgrowerstomeet

strongconsumerdemandforlocalgreensduringthe“off”season.

Withthegoalofprovidingrecommendationsforwinterspinachproductioninhightunnels,we

performedexperimentsovertwowinterseasonsusingfall-plantedspinachseedlings.We

focusedprimarilyonthreespinachvarieties:Regiment,Space,andTyee,andplantedthese

varietiesatsixdifferentdatesthroughoutthefall,rangingfrom20Septemberto9November.

Atourthirdplantingdate(9Oct)weaddedfivevarietiestothestudy:Carmel,Corvair,Gazelle,

EmperorandRenegade.Thestudyobjectiveswereto:

1. DetermineyieldpotentialofRegiment,Space,andTyeeforeachfalltransplantdate

andidentifybesttransplantdates

2. Evaluatealleightvarietiesfortheirsuitabilityforwinterproduction3. Assesstheleafsugarcontentamongvarietiesthroughoutthewinterseason

4. Identifydiscernablegrowthandleafcharacteristicsamongvarietiesthatmayassist

growersinchoosingthosebestsuitedtotheirmarket/objectives

MethodsTrialswereconductedatUNH’sWoodmanHorticulturalResearchFarm,attheAgricultural

ExperimentStationinDurham,NH(zone5B)overtwowinterseasons:2014-15and2015-16.

Thesamesixplantingdateswereutilizedinbothyears.

PlantingDate SeedingDate TransplantDate VarietiesUsed#1 29August 20September Regiment,Space,Tyee

#2 8September 30September Regiment,Space,Tyee

#3 18September 9OctoberRegiment,Space,Tyee,Carmel,

Corvair,Gazelle,Emperor,Renegade

#4 29September 19October Regiment,Space,Tyee

#5 9October 30October Regiment,Space,Tyee

#6 19October 9November Regiment,Space,Tyee

Seedsweresourcedfrom:

HighMowingOrganicSeeds:Regiment&Corvair

Johnny’sSelectedSeeds:Space,Tyee,Carmel,Gazelle,Emperor&Renegade



Unheatedhightunnelswereusedinbothyears.Duringthe2014-15season,weuseda60’x30’

stationaryhightunnel(LedgewoodFarms,Moultonborough,NH).Thetunnelwascoveredwith

asinglelayerof6mil,4-yearUVtreatedpolyethyleneplasticwithpolycarbonateendwallsand

wasequippedwithtwolouverventsandexhaustfanssettoventat70°F.Roll-upsideswere

manuallyadjustedforadditionalventilationandwerepermanentlyloweredforthewinteron

October19,2014.

In2015-16,a48’x30’moveableRollingThunderhigh

tunnel(RimolGreenhouseSystemsInc.,Hooksett,NH)was

used.Thetunnelwascoveredinaninflateddoublelayer

of6mil,4-yearplasticandalsohadpolycarbonateend

walls.Gableshuttersventedat60°F,andautomatedroll-

upsidesmaintainedaninsidetemperaturebelow70°F.

Ventilationthroughtheautomaticroll-upsideswas

disabledforthewinteronDecember13,2015.

CulturalDetails:Soilwithinhightunnelswastestedandamended(pre-plantincorporated)basedon

recommendationsforspinach.Inbothyears,we

constructedfourlongbedsrangingfrom4-5’wideand40-

50’long,dependingonhightunnelused,withenough

spacebetweenrowstoaccommodateharvesting.

Germination&Transplant:Seedswerestartedin128-celltraysofPro-MixBXsoillessmedia.In2015,veryhigh

temperaturesinlateAugustinhibitedgerminationofthe

firstseeding.Toensureadequateplantquantitiesforthe

study,alllaterplantingsweregerminatedinagrowth

chamber(PercivalScientific,Perry,IA)setat60°Ffor7

days.Seedlingsweretransplantedat3weeksofagein

rows8”apartwithanin-rowspacingof5”.Weuseda

randomizedcompleteblockdesignwithfourreplicatesof

eachvariety/plantingdatecombination,24plantsperrep.

ManagementIrrigation:Seedlingswereirrigatedfollowingtransplantandasneededusingacombinationofdriptape(2014-15)

andoverheadirrigation(2015-16).Itwasnecessaryto

providewaterduringthewintermonths,especially

December-Februaryin2015-16.

Raisedbedspriortoplanting,

September2015

Seedlingsreadyfortransplant,

October2015



Rowcover:Whentemperaturesbegantoconsistentlydipbelow

freezing,anAgribon+AG-19,0.55oz/yd2rowcoverwassuspendedapproximately3’aboveplantsforadditionalinsulation.Therow

coverwasapplied6November(2014-15)and14December(2015-

16).Foreasyremoval,welaidthecoveracrossfourcablesthat

wereinstalledtorunthelengthofthetunnel.Itwaskepttautby

clippingthecovertotheoutertwocableswithclothespinssoitdid

notmakedirectcontactwithplants.Duringthewinter,thecover

wasonlyremovedforthepurposeofharvestingandirrigation,and

inbothyearswaspermanentlyremovedinMarchwhendaytime

temperaturesbeganreaching50°F.Pestmanagement:In2015-16,Bacillusthuringiensis(DipelDF)

wasappliedtwicetocontrolcutworm(6Novemberand10

December).Wecontrolledahighaphidpopulationin

February2016bythreereleasesofladybeetles(Hippodamiaconvergens;A-1UniqueInsectControl,CitrusHeights,CA).

HarvestInyearone,harvestingbegan30October2014and

concludedon15April2015,whenplantsbolted.Inyeartwo,

harvestingbegan19October2015andended8April2016.

Carmelwastheonlyvarietytoboltbythetimeharvesting

wasterminatedin2016.Webeganharvestingwhenleaves

reachedmarketablesize,definedas4-6”frompetiolebase

tothetipoftheleafapex.Ateachharvest,allleavesof

marketablesizewereremovedbypinchingthebaseofthepetiole.Harvestswereconducted

approximatelyeverytwoweeksfromOctoberthroughApril,withtheexceptionofJanuaryand

Februarywhenweharvestedoncepermonthduetotheslowerpaceofplantgrowth.

Rowcoveroverspinach,

December2015

TaliaLevyharvestson18December2015.

Ladybeetleshuntforaphids,

April2016



RESULTS:PlantingDateDays-to-harvest:Thenumberof

daysfromtransplanttofirst

harvestincreasedsteadilywith

eachlatertransplantdate.With

theexceptionofthefirst

transplantdatein2015-16

(whichwasplaguedbypoor

germination),daystoharvest

washighlydictatedbytransplant

date.ThisisshowninFigure1.Thisperiodwasasshortas19

days(transplant#2in2015)and

aslongas130days(transplant

#6in2014).Weattributethe

variationbetweenyearstothe

differenceintemperature

betweenwinterseasons,asshowninFigure2.

Yield:Plantingdatealsoimpactedthetotalyieldfrom

firstharvestthroughlastharvest;withearlier

transplantdatesproducingsignificantlyahighertotal

yieldthanlatertransplantdates.Figure3showsthedifferenceinyieldbytransplantdate,andyear.During

thefirstyearofthestudy(2014-15),thefirstthree

dateshadsimilartotalyields,thoughthesecondwas

technicallylowerthanthefirst.Inthesecondyearof

thestudy(2015-16),thefirsttwotransplantdatesdid

notdifferfromoneanotherintotalyieldatall.However,inbothyearsweobservedyields

tendedtodecreasesteadilywitheachconsecutiveplantingdate.

The2015-16season

producedmuchhigher

yieldsthan2014-15,

mostlikelyduetoavery

mildwinter.

40# 44# 48#

81#

98#

130#

29#19# 21# 25#

36# 39#

0#

20#

40#

60#

80#

100#

120#

140#

#1#(9/20)# #2#(9/30)# #3#(10/9)# #4#(10/19)# #5#(10/30)# #6#(11/9)#Da

ys%un(

l%1st%Harvest%

Transplant%Date%

2014/15#

2015/16#

Figure1.Daystoharvestforeachofthesixtransplantdatesduring2014-15and2015-16.

Figure3.Averagetotalyieldforeachtransplantdate.

Valuesareanaverageof

Regiment,SpaceandTyee.

Valueswiththesameletter

arenotsignificantlydifferent

fromoneanother,*within

eachyear.

0.66$a*$ 0.56$

b*$

0.60$ab*$

0.41$c*$ 0.34$

cd*$0.29$d*$

1.31$a$ 1.18$

a$

0.93$b$

0.80$b$

0.60$c$ 0.54$

c$

0.00$

0.20$

0.40$

0.60$

0.80$

1.00$

1.20$

1.40$

#1$(9/20)$ #2$(9/30)$ #3$(10/9)$ #4$(10/19)$ #5$(10/30)$ #6$(11/9)$

Yield&in&lbs/+2

&

Transplant&Date&

2014515$2015516$

0.0#

10.0#

20.0#

30.0#

40.0#

50.0#

60.0#

Nov# Dec# Jan# Feb# Mar# Apr#

Tempe

rature)in°F)))

Month)

2014915#

2015916#

Figure2.Averagemonthlytemperatures.



Duringthesecondyearofourstudy,thefirsttransplantdate(20Sept)producednearlythree

timesthecumulativeyieldthanthelatesttransplantdate(9Nov),andinthefirstyearofthe

study,itwasdouble.Thisvariationintotalyieldamongtransplantdatesdemonstratesthe

importanceofkeepingthetargetmarketinmindwhenchoosingatransplantdate.

Iffall/earlywinterproductionisthe

objective,ourstudysuggeststhat

earliertransplantdateswillresults

inthehighestautumn/earlywinter

yields.AsshowninFigure4,the20Septand30Septtransplantdates

producedsignificantlymoreby

Januarythananyofthelaterdates.

Itisalsoclearthattransplanting

laterthanmid-Octoberresultsin

littleproductionpriortoandduring

theholidayseason(apotentially

importantmarket).

However,iffallproductionisnota

primaryobjectiveandinstead,early

androbustspringyieldsaredesired,

wefoundthatthefirstfourfall

transplantdatesresultedinthe

samespringyield.Therefore,

waitingtotransplantintothetunnel

untilmid-Octobershouldnot

negativelyimpactspringyields.

Additionally,eventhelatestplanting

dates(30Octand9Nov)produced

goodspringyields,andharvesters

notedplantsfromtheselater

transplantdateshadhigherquality

leavesandamoredesirableplant

typeforharvesting(lessbushy)

duringMarchandAprilthanspinach

transplantedatearlierdatesinthe

fall.Figure5depictsthedifferenceinspringproductionamongfall

transplantdates.

20#Sep'(a)'

30#Sep'(b)'

9#Oct'(c)'

19#Oct'(d)'

30#Oct'(e)'

9#Nov'(f)'

0.00'

0.10'

0.20'

0.30'

0.40'

0.50'

0.60'

0.70'

0.80'

October' November' December' January'

lbs//2

'

Figure4.Averagetotalfall&earlywinteryield(acrossallvarieties).Valuessharingthesameletterarenotsignificantlydifferentfrom

oneanother.

20#Sep'(a)'

30#Sep'(ab)!

9#Oct'(ab)'

''

19#Oct'(ab)'

30$Oct!(b)!9$Nov!(b)!

0.00!

0.10!

0.20!

0.30!

0.40!

0.50!

0.60!

February! March! April!

lbs/52'

Figure5.Averagetotalspringyield(acrossallvarieties).Valuessharingthesameletterarenotsignificantlydifferentfromone

another.



RESULTS:VarietySelectionDuringbothyearsoftheexperiment,Regimentand

Spaceperformedsimilarlyintermsofyieldand

producedsignificantlyhighertotalyieldsthanTyeewhen

allsixtransplantdateswereconsidered.SeeFigure6.Tyeealsoexhibitedotherundesirablecharacteristicsin

ourtrials,suchasexcessiveleafcurlingandbrittleness.

SeeFigure3foranapproximatetotalyieldforeach

plantingdate.

CumulativeyieldsfromCarmel,Corvair,Emperor,

Gazelle,andRenegadeareavailableforasingle

transplantdate,9Oct.Inbothyears,weobservedno

differenceinyieldbetweenthesecultivars.Theydid,however,exhibitdifferencesinleafcolor,

shapeandsize,andplant

type/growthhabit.Figure7showsproductionbymonth

forthesecultivars.While

therewerenodifferencesin

totalyield,Corvairand

Renegadeproducedhigher

yieldsthanothervarieties

duringthecoldestmonths:

Januaryandespecially

February.Qualitativenotes

identifiedCorvairasa

“favorite”duringwinter

monthsforitsattractive

leavesandgrowthhabit.

Additionally,Corvairwasthe

onlyvarietytoincreasein

leafmassafterthewinter

months.

RESULTS:SugarContent(°Brix)Thesugarcontentinfruitsandvegetablesisoftencorrelatedwithtasteandeatingquality,with

highersugarlevelsbeingmorefavorabletoconsumers.°Brixisameasureofthegramsof

solublesolids,primarilysucrose(tablesugar),inasolution-inthiscase,theliquidextracted

fromspinachleaves.Othersolublesolidssuchasantioxidantsarealsoheightenedunder

stressfulconditions,suchascoldtemperatures,andarebeneficialtohumanhealth.

Variety 2014-15 2015-16

Regiment ab a

Space a ab

Tyee b b

Figure6.Yieldperformanceofthree

primaryvarieties.Valuessharingthe

sameletterarenotsignificantly

differentfromoneanother,‘a’isthe

highestyielding.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Carmel Corvair Emperor Gazelle Renegade

lbs/62

April

March

February

January

December

November

Figure7.Monthlyyieldsofeachvarietyduringthe2015-16winter

season.Valuessharingthesameletterarenotsignificantly

differentfromeachother.



Wemeasuredthesugarcontentofeachspinachvarietyfollowingharvesttodetermineif

differencesinsweetnessexistedamongcultivars,andhowairtemperaturewithinthehigh

tunnelatourlocationaffectedthesemeasurements.Weobservedtwotrends:

1) Thehightunnelairtemperatureinthedays/weeksleadinguptoharvestimpacted

solublesolidcontentwithinthespinachleaves

2) Varietyhasaninfluenceonsugarcontent TemperatureInbothyearswe

recordedadirect

relationshipbetween

temperatureand°Brix

measurements,with

coldertemperaturesin

thedaysleadingupto

harvestheighteningthe

sugarcontentinthe

leaves.Asdepictedin

Figure8,thelowestsugarmeasurements

wererecordedduring

thewarmestperiodsof

theexperiment(Oct,

Nov,March,andApril),

andthehighest

measurementswere

recordedduringthe

coldestmonths,

Februaryinparticular.

VarietyVarietyalsohadasignificantimpactonaverage

°Brixlevels,withGazelleandEmperorhaving

higheraveragesugarcontentthanother

varietiesduringbothyears.Despitethis

statisticallysignificantdifferenceinsugar

contentamongvarieties,therangeof

differencein°Brixisn’tenormous,andwefelt

allvarietieswereofahigheatingquality.We

didnotconductrawtastetestsofeachvariety.

Average°Brix

acrossallsamplingdatesVariety 2014-15 2015-16Gazelle 11.1 a 6.35 a

Emperor 9.56 b 6.29 a

Space 9.21 c 6.03 b

Carmel 9.08 cd 6.00 b

Corvair 8.94 d 5.60 c

Renegade 8.70 e 5.25 d

Regiment 8.46 f 5.54 c

Tyee 8.24 g 5.63 c

30.00$

35.00$

40.00$

45.00$

50.00$

55.00$

60.00$

0.00$

2.00$

4.00$

6.00$

8.00$

10.00$

12.00$

30+Oct$ 6+Nov$ 13+Nov$ 23+Nov$ 5+Dec$ 18+Dec$ 8+Jan$ 19+Feb$ 4+Mar$ 25+Mar$ 8+Apr$

Air$T

empe

rature$(°F)$

Sugar$in$°Brix

$$

Harvest$Date$

Average$Sugar$Measurement$in$°Brix$Average$Air$Temperature$

Figure8.Averageairtemperaturesand°Brixmeasurementsduringthe2015-16

experiment.°Brixvaluesareaveragedacrossalleightvarietiesandwere

calculatedusingonlythethirdplantingdate.Averagetemperatureswere

calculatedusingthedaysbetweenharvestsorthetwoweekspriortoharvest,

whicheverwaslonger,andexcludedharvestdays.

Figure9.Average°Brixreadingsforeachvarietyduringbothyearsoftheexperiment.Values

sharingthesameletterarenotsignificantly

differentfromoneanother.



Tips&Takeawaysforwinter&earlyspringproductionofspinachinunheatedhightunnels.TransplantDate

⋅ TransplantseedlingsinSeptemberiftheholidayseasonisatargetmarket.September

plantingswillalsoresultsinthehighesttotalyieldthroughspring.⋅ Ifonlyspringproductionisofconcern,transplantinganydatefrommid-September

throughmid-Octoberwillresultinsimilarspringyields.Transplantingmid-October

throughearlyNovemberalsoresultsingoodspringyields(butwillnotproducemuch

priortospring).MoistureMaintainingadequatesoilmoisturethroughouttheentirewinterseasonisnecessaryin

preventingplantlossandensuringgrowthduringthesemonths.Don’tbetrickedbythesnow

outside,keepcheckingmoisturelevelsandirrigatewhenneeded.

PestManagement

Ladybeetleswereeffectiveincombattingouraphidpopulationin2015-16,butatleasttwo

harvestswerenotmarketableduringtheinfestation.Usingladybeetlespreventativelyor

anotheraphidcontrolstrategymaybenecessaryifyouexperiencehighaphidpopulations.

Variety

Seebelow,andthe‘SpinachVarieties’sheetforpicturesanddetailedinformation.

Figure10.Thetableaboveshowshowvarietiesperformedduringspecificmonths.Thosein

greenboxesproducedhigheryieldsthanthoseinredforthemonthspecified.Varietiesingrey

wereneitherhighernorloweryieldingthanthoseingreenorred.Theserankingsarebasedon

our2015-16results.

Formoreinfoorwithquestions,pleasecontactKaitlynOrde([email protected])or

BeckySideman([email protected];603-862-3203).

ACKNOWLEDGEMENTS:WereceivedfinancialsupportfromtheNHAgriculturalExperimentStation,the

NHVegetable&BerryGrowers’Association,andUNHCooperativeExtension.WethankJohnMcLean,

EvanFord,DavidGoudreault,LukeHydock,NatalieStimpsonandMeganPhelanfortechnicalsupport

throughoutthestudy,andJohnny’sSelectedSeedsforprovidingseedsforthisexperiment.

TheUniversityofNewHampshireCooperativeExtensionisanequalopportunityeducatorandemployer.

UniversityofNewHampshire,U.S.DepartmentofAgricultureandN.H.countiescooperating.

October November December January February March April

RegimentRegiment

Space

Tyee

Carmel

Corvair

Emperor

Gazelle

Renegade

Regiment

Space

Renegade

Regiment

Renegade

Emperor

Regiment

Renegade Regiment

Space

Tyee

Carmel

Corvair

Emperor

Gazelle

Renegade

Regiment

Tyee

Carmel

Corvair

Emperor

Space

Corvair

Space

Corvair

Emperor

Gazelle

Carmel

Corvair

Emperor

Gazelle

Renegade

SpaceTyee

Gazelle

Tyee

Gazelle

Carmel

Tyee

Carmel

Space

Tyee



SpinachVarieties,2014-16ByKaitlynOrde&BeckySidemanThequalitativeobservationsbelowarebasedonourtrials,andmaynotreflectperformanceunderotherconditions.

Regiment Lightly-savoyedleafSlightlyuprightgrowthhabitDMR*races1-7-Arrowheadshaped-Nicelighttexturetoleaf`

CarmelSlightly-savoyedleafVeryuprightgrowthhabitDMRraces1-11,13-Lovelysmallerleaves,idealforfresheating/babyproduction-Verybushyplant-Timeconsumingtoharvest

GazelleSmoothleafVeryuprightgrowthhabitDMRraces1-13-Darkshinyleaves-Increasedinbushinessoverwinterseason-Tendencytoslightlyyellowontheedges

SpaceSmoothtolightly-savoyedSlightlyuprightgrowthhabitDMRraces1-3,5,6,8,11,12-LateOct&Novtransplantsproducedveryhighqualityleavesthefollowingspringthatplantsthattendednottobeoverlybushy

CorvairSmoothleafSlightlyuprightgrowthhabitDMRraces1-11(possibly13)-Veryattractiveleaves,-FavoriteduringMar&Aprforconsistentsizeandgoodquality-Quicktoharvest

RenegadeSmoothleafOblategrowthhabitDMRraces1-7-Roundedleafapex-Nicebutstrongtexture-Quicktoharvest

TyeeVery-savoyleafSlightlyuprightgrowthhabitDMRraces1-3-Tendencytoexhibitexcessiveleafcurlingandhavebrittleleaves

EmperorSemi-savoyedVeryuprightplantDMRraces1-10-Nicelighttexturetoleaf

UprightgrowthhabitofEmperor(L)nexttothemoreoblateRenegade(R).

*DMR=DownyMildewResistance.Resistanceinfoobtainedfromseedsources.

winter spinach production in high-tunnels, 2014-2016 · winter spinach production in high-tunnels,...

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