Environmental Environmental Requirements for Requirements for Plant GrowthPlant Growth

Unit 4 Introductory HorticultureUnit 4 Introductory Horticulture

LightLight

Intensity: Brightness. Foot-candle is the Intensity: Brightness. Foot-candle is the form of measurementform of measurement

Day-length or Photoperiod: time in lightDay-length or Photoperiod: time in light Long day: summer annuals (marigolds)Long day: summer annuals (marigolds) Short day: short photoperiods (poinsettia)Short day: short photoperiods (poinsettia)

Color: red spectrum -> blue spectrum Color: red spectrum -> blue spectrum plants need both, sun has bothplants need both, sun has both

TemperatureTemperature

Varies from plant to plantVaries from plant to plant Sun lovers can take high temps with Sun lovers can take high temps with

plenty of water and humidityplenty of water and humidity Greenhouse tempGreenhouse temp

Germination 65-75Germination 65-75ooFF Growth 55-65Growth 55-65ooFF

WaterWater

Necessary for 13 of 16 nutrient uptakeNecessary for 13 of 16 nutrient uptake Growth and MaintenanceGrowth and Maintenance

PhotosynthesisPhotosynthesis Sap – transport nutrientsSap – transport nutrients Transpiration – coolingTranspiration – cooling Turgor – plant shape due to cell shape, Turgor – plant shape due to cell shape,

opposite of turgor is wiltopposite of turgor is wilt

Water (continued)Water (continued)

Methods and FrequencyMethods and Frequency Infrequent, thorough watering is bestInfrequent, thorough watering is best Container plants: bottom watering is bestContainer plants: bottom watering is best

Encourages root growthEncourages root growth Dry soil helps reduce diseaseDry soil helps reduce disease

HumidityHumidity

40-60% is ideal40-60% is ideal Cold winter days and hot summer days Cold winter days and hot summer days

humidity is too lowhumidity is too low Plant misters can be usedPlant misters can be used

MediaMedia

Soil (natural media), Artificial, Soil (natural media), Artificial, Hydroponics (no media)Hydroponics (no media)

Support the plantSupport the plant Consistency of volume – wet or dryConsistency of volume – wet or dry Adequate porosity (drainage, aeration)Adequate porosity (drainage, aeration) Provide nutrients (13 needed from soil)Provide nutrients (13 needed from soil) Correct pH for plant (most plants 6.5-7)Correct pH for plant (most plants 6.5-7)

NutrientsNutrients

Plants need 16 nutrientsPlants need 16 nutrients Organic macro nutrientsOrganic macro nutrients

Carbon, hydrogen, oxygenCarbon, hydrogen, oxygen

Essential nutrientsEssential nutrients NitrogenNitrogen PhosphorusPhosphorus PotassiumPotassium

Sterilization Sterilization (Applies to Media)(Applies to Media)

Free of disease, weed seeds, parasites, Free of disease, weed seeds, parasites, insectsinsects

180180ooF for 30 minutes – steam dry heatF for 30 minutes – steam dry heat Chemical sterilization – methyl bromide Chemical sterilization – methyl bromide

gasgas Steam heat – commercial greenhouseSteam heat – commercial greenhouse Chemical – commercial greenhouseChemical – commercial greenhouse

Insects and DiseasesInsects and Diseases

Sources and PreventionSources and Prevention Media: sterilizeMedia: sterilize Infected Plants: buy good quality plants from Infected Plants: buy good quality plants from

reputable greenhousesreputable greenhouses Watering: bottom watering whenever possible, avoid Watering: bottom watering whenever possible, avoid

splashingsplashing ControlsControls

Insects: spray, dip, discardInsects: spray, dip, discard Weeds: pull, sprayWeeds: pull, spray Disease: discardDisease: discard