protecting

ProtectingPlantsfrom

ColdTemperatures

AlthoughweliveintheSouth,winter

sometimesbringscoldtemperatures

thatcancauveredamageto

frostaftertemperaturerisin

JanuaryorFebruarycouldbeeven

worthanthesamecold

temperatureinwintersuchaswhat

,

itisimportanttoprotectplantsfrom

thecoldtemperatures.

TemperatureChanges

andPlantDamage

Aplant’sabilitytowithstandcold

temperaturesdependsonplant

species,andhowlowandhowfast

temperaturesgraduallydecrea,a

plantcanacclimate,oradjustitlf,to

withstandcoldertemperaturesbetter.

Suddendecreasintemperature

caumoredamageinfallorearly

winterthansimilarlowtemperatures

eratures

increaduringthewintermonths,

someplantsmaybreakdormancy,or

deacclimate,andbeginleafingoutor

thatbreakbud

dormancybecomemoresusceptible

tolatefrostbecauoftheirnew,

tendergrowth.

Coldinjurycanoccurtoallparts

oftheplant(flowers,fruits,leaves,

stems,trunks,roots,andbuds).Fruits

andflowersaretheleasttolerantof

coldinjurybecautheyhavelittle

abilitytoadjustorbuilduptolerance

dstem

tissuesareinjuredanddamaged

wheniceformswithintheplant’s

cellsthattypicallyoccursduringa

ishappens,the

plant’stissuediesandisoften

characterizedbyplantpartsturning

e

temperaturedropsslowly,ice

sometimesformsbetweenthewalls

oftheplant’rcold-

acclimatedplantscanoftenwithstand

thistypeoficeformation.

Windyconditionscanalsocau

plantdamagebydesiccation,orthe

al,or

leaf-tip,burnortotallybrownleaves

inverecascharacterize

ationoccurswhen

aplantlosmorewaterthanit

absorbs,ortakesup,bytheroots,

especiallywhenthegroundisfrozen.

PreventiveMeasures

HomeownersinMississippicanenjoy

awidevarietyofplantmaterials.

Theycanincreatheirchoiceof

availableplantsbyasssingand

maintainingplantneedsandby

carefullylectingplantsandsite

tingacombination

oftenderandhardyplantsand

byprotectingplantssusceptibleto

coldtemperatures,homeowners

canhavelandscapesthatsurvive

coldtemperatures.

ProtectingPlants

fromColdTemperatures

PlantandSiteSelection

Thebestwaytopreventcoldinjurytoplantsis

tochooplantsthattoleratethecold

sippiisinthe

regionsofMississippiareinZone7A,which

meansthatplantsneedtobehardyto0to15ºF.

NorthandnorthcentralregionsofMississippi

areinZone7B(5to10ºF);centralMississippiis

inZone8A(10to15ºF);andthecoastalportion

ofMississippiisinZone8B(15to20ºF).Select

plantsthatmeettheminimumcold-hardy

requirementsinyourarea;forexample,ifyou

liveinZone7,chooplantsthatarehardyto

Zone6toensuretheywillwithstandthecold

lectingcold-

tolerantplants,makesurethattheplantsalso

toleratesummertemperaturesinyourarea.

Inadditiontoproperplantlection,proper

yourproperty

todeterminethelocationofthecoldestandthe

thewinter,thecoldest

spotsareoftenfoundonthenorthand

northwestpartofthepropertyandinlowareas

mestspotsare

usuallyonthesouthernpartoftheproperty.

Asssingthemicroclimatesofyourproperty

ion,landform,soil

properties,canopycover,andproximityof

structuresorotherplantsdeterminea

limatescanbeudto

helpprotectplantsbyplacingcold-nsitive

plantsnearthepartofthehouthatreceives

southernexposureornearlargerplantsor

otherstructures.

PlantNutrition

Maintainingproperplantnutritionalsohelps

nutritionofplantsiscritical:Aplantthathas

beengiventheappropriatenutritiontolerates

coldtemperatures,withstandssuddentemp-

eraturedrops,andrecoversfromcolddamage

betterthanplantsthatarenutritionallydeficient.

Fertilizingplantsatthepropertimeofyear

izingplantsinthefall(after

AugustorSeptember)withafertilizerhighin

nitrogencanresultinaflushofnewgrowththat

ismoresusceptibletocoldtemperatures.

Duringthefallandwintermonths,most

plantnteradormantperiodwhentheyneed

izing-formulated

fertilizers,whicharehighinpotassiumandlow

innitrogen,maybeud.

CanopiesandShade

Treecanopiescanreducecoldinjuryfrom

ionalfreezesoccuron

calm,clearnightswhentemperaturesdrop

becauofradiationalcoolingorheatlossfrom

theearthandfromthesurfacesofobjects.

Canopieshelpreduceradiantheatlossfromthe

groundtotheatmospherebyraisingthe

minimumnighttemperaturebeneaththem.

Plantsthatgrowinshadedareasareless

susceptibletowinterdesiccation,ordryingout,

nts

thatpreferfullsundonotdowellintheshade

andwillbeunhealthyandlesstolerantofcold

temperaturesifyouplantthemintheshade.

Windbreaks

Windbreakssuchasfences,buildings,and

temporarycoveringscanhelpprotectplants

eaksaremostufulin

reducinginjuryresultingfromcoldwindsand

advectivefreezes(freezesthatoccurwhen

temperaturesdropbecauoftheinvasionof

coldairmassintothearea).

CoveringandHeating

Protectplantsthatareincontaineritherby

placingtheminsideaprotectivestructure

(hou,garage,greenhou,orshed)orby

placingaprotectivecoveringoverthem.

Containerplantsareespeciallysusceptibleto

ootsaremoreexpod

hatare

damagedbycoldtemperaturesmaynotshow

immediatesignsofdamage,buttheplantswill

showsignsofstresswhentemperaturesincrea.

Pushtogethercontainerplantsthatareleft

outsideandmulchorcoverthemtodecrea

thebaofthecontainersinplastic,burlap,or

blanketstoreduceheatloss.

Plantsthatgrowclotothegroundare

usuallyprotectedbyheatradiatingfromthesoil.

Plantsthataretallandmoreopendonotreceive

thisradiatingheatandarenotprotectedfrom

thecold.

ng

protectstherootsofplantsandhelpsreduce

heatloss,thusminimizingtemperature

shrubsandtrees,

protectingtherootsisnecessaryforthemto

survivethecoldandcomebackinthespring.

Coveringyourplantshelpsprotectthem

fromfrostaswellasfromextremelycold

thatreachthegroundand

donotcomeincontactwithfoliageformalayer

preventfoliagebreakage,avoidhavingthe

covers(sheets,blankets)touchthefoliage.

Whenextremelycoldtemperaturesare

predicted,placealightbulb(60wattis

sufficient)orotherheatsourceunderthecover

carefulwhenusinga

bulborotherheatsource,whichcanbea

etthebulborheat

sourcecomeincontactwiththeplantorthe

thecoverandprovideventilation

duringthedaytoallowreleaoftheheatthatis

ecautionis

criticalwhenusingplasticcovers.

WaterNeeds

BeforeaFreeze

Wateringplantsbeforeafreezecanhelpprotect

atiswellwatered

absorbsmoreheatandthenreradiatesheat,

helpingtoincreatheelevatedtemperature

r,poorlydrained

soilsresultinplantsthathaveweakandshallow

roots,whicharemoresusceptibletocoldinjury.

Tohelpplantspreventthelossofsoil

moisture,mulchthesoil.

DuringaFreeze

Coldweathercanalsocauthegroundto

isoccurs,waterisunavailableto

roots;plantscontinuetotranspire(lowater

fromtheirleaves)and

ngthesoiltothawtheground

makeswateravailabletoroots.

Youcanprotectplantsduringafreezeby

linghelps

keepthetemperaturesoftheleafsurfacenear32

ºlinghelpsprotectplantsbyusing

latentheat,whichisreleadwhenwater

ect

plantswiththismethod,sprinklewhenfreezing

temperaturesarereachedandcontinueuntil

thawingiscompleted.

Evenlydistributewaterovertheplantsand

supplyenoughtomaintainafilmofliquidwater

advantageisthat

ifsprinklingiscarriedoutforveraldays,the

soilmaybecometoosaturatedandmaydamage

rootsystemsorcauplantdamageresulting

fromicebuildup.

AfteraFreeze

Checkthewaterneedsofplantsafterafreeze.

Afterverycoldtemperatures,waterthatisinthe

soilmaystillbefrozenandunavailabletothe

tsaretranspiring(losingwater

fromtheirleaves)andwaterisunavailableto

theroots,plantsmaydryout.

Toprovidewaterforplants,applywatertothaw

thesoilandtheice.

Pruning

Pruninginlatesummerorearlyfallcanresultin

newgrowththatismoresusceptible

tocoldinjury;soavoidpruningatthistime

ofyear.

Waittopruneplantsuntilnewgrowth

gto

pruneafterfreezeshavepastwillguardagainst

dplantsmaynot

breakbudinthespringandmaytakeonan

tipsaremore

likelytosuffercoldinjurythanolderwood.

Todetermineifwoodhasbeeninjuredby

thecold,checkthecambiumlayer(layerdirectly

underthebark)forblackorbrowndiscolor-

hiswoodbelowthediscoloration.

Todetermineifyourfruitplantshavebeen

damagedbythecoldtemperatures,waitveral

daysafterafreezeandremoveveralflower

arpknifeorrazor

bladetocutacrossctionofthebud’

thereisanydiscolorationinthebud,thebudhas

beendamagedandwillnotproducefruit.

Damagemaybelocalized,however,andnotall

budsmayhavebeendamaged.

blicationmaybecopiedanddistributed

withoutalterationfornonprofiteducationalpurposprovidedthatcreditisgiventotheMississippiStateUniversity

ExtensionService.

ngGu,AssistantExtensionProfessor,aSkelly,Ph.D.,

formerConsumerHorticultureSpecialistDiscriminationbaduponrace,color,religion,x,nationalorigin,age,disability,orveteran’sstatusisaviolationof

minationbaduponxualorientationorgroup

affiliationisaviolationofMSUpolicyandwillnotbetolerated.

Publication2303

ExtensionServiceofMississippiStateUniversity,hed

infurtheranceofActsofCongress,May8andJune30,,Director(PODrev.09-07)

Summary

Healthyplantsaremoreresistanttocoldinjury

thanplantsthatareweakenedbydia,byinct

damage,orbyimpropercare.