Chapter 20Chapter 20

Greenhouse Production Greenhouse Production TechniquesTechniques

The production of greenhouse crops The production of greenhouse crops can be compare to the manufacture can be compare to the manufacture of non-plant items in one way: of non-plant items in one way: scheduling is important.scheduling is important.

To grow and sell when the season To grow and sell when the season and market are best is an example of and market are best is an example of why timing is important in why timing is important in greenhouse production.greenhouse production.

Timing is everything in the flower Timing is everything in the flower production business.production business.

To determine whether or not to To determine whether or not to increase or decrease the number of increase or decrease the number of plants produced from year to year a plants produced from year to year a grower can look at a record of last grower can look at a record of last year’s sales.year’s sales.

Four purposes of root Four purposes of root media:media:

– Provide nutrientsProvide nutrients– Retain waterRetain water– Allow aerationAllow aeration– Anchor the plantAnchor the plant

Drainage is essential when field soils Drainage is essential when field soils are used in greenhouse crop are used in greenhouse crop production.production.

Three reasons soil pasteurization Three reasons soil pasteurization may be needed:may be needed:– Weed seedsWeed seeds– PathogensPathogens– insectsinsects

Pasteurization – heating soil for 30 Pasteurization – heating soil for 30 minutes at 180 degrees F to kill minutes at 180 degrees F to kill undesirable things in the soil.undesirable things in the soil.

Four methods of pasteurizing growing Four methods of pasteurizing growing media:media:– Surface steamingSurface steaming– Buried pipesBuried pipes– Closed container steamingClosed container steaming– Chemical fumigantsChemical fumigants

Pasteurization only kills harmful things Pasteurization only kills harmful things in the soil while sterilization kills every in the soil while sterilization kills every thing.thing.

Three reasons growers need soil test:Three reasons growers need soil test:– Check pHCheck pH– Check for nutrient deficienciesCheck for nutrient deficiencies– Measure soluble salt contentMeasure soluble salt content

Two factor to consider when selecting Two factor to consider when selecting containers:containers:– Crop Crop – Time of yearTime of year

Containers in greenhouse production:Containers in greenhouse production:– PotsPots– Clay containersClay containers– Plastic containersPlastic containers– Peat potsPeat pots– Molded plasticMolded plastic– Hanging basketsHanging baskets– Flats Flats

Reproduction methods:Reproduction methods:

– SeedSeed – bedding plants and geraniums – bedding plants and geraniums– RunnersRunners – spider plants – spider plants– BulbsBulbs – tulips, other flowering perennials – tulips, other flowering perennials– LayeringLayering – fig and rubber plants – fig and rubber plants– CuttingsCuttings – geraniums, and many foliage – geraniums, and many foliage

plantsplants– GraftingGrafting – some azaleas – some azaleas– BuddingBudding – roses – roses– Division of the crown Division of the crown – foliage plants– foliage plants– Tissue and organ culturing Tissue and organ culturing – orchids, – orchids,

bromeliad, carnation, and chrysanthemumsbromeliad, carnation, and chrysanthemums

Of the numerous methods of Of the numerous methods of reproduction used by reproduction used by

greenhouse growers, seeds and greenhouse growers, seeds and cuttings are most common.cuttings are most common.

The spacing of a crop is very important. The spacing of a crop is very important. Wide spacing is costly due to space, Wide spacing is costly due to space, material, and labor issues. However, it material, and labor issues. However, it helps plants to grow fuller and thicker, helps plants to grow fuller and thicker, allowing them to sell better.allowing them to sell better.

Fixed spacing – no movement of pots Fixed spacing – no movement of pots after planting.after planting.

Expanding spacing – crops started in Expanding spacing – crops started in small pots with close spacing, then small pots with close spacing, then container size and spaces can be container size and spaces can be increased as crop matures.increased as crop matures.

Four conditions from crowded Four conditions from crowded spacing:spacing:– Reduce photosynthesisReduce photosynthesis– Increase possibility of diseaseIncrease possibility of disease– Reduce air circulationReduce air circulation– Shaded or overly most foliageShaded or overly most foliage

Labeling – identifying the plants on Labeling – identifying the plants on the bench.the bench.

Watering done correctly become Watering done correctly become irrigation, the maintenance of proper irrigation, the maintenance of proper balance of both moisture and air in balance of both moisture and air in the soil of crops.the soil of crops.

Too much water leaves too little Too much water leaves too little airspace, and the root system may airspace, and the root system may rot.rot.

Too little water can also cause shallow Too little water can also cause shallow root development, soluble salt buildup, root development, soluble salt buildup, and reduced plant and blossom size.and reduced plant and blossom size.

Nature can be blamed for a lot that Nature can be blamed for a lot that goes wrong in a greenhouse, but not a goes wrong in a greenhouse, but not a water excess or deficiency.water excess or deficiency.

The first and most difficult thing a new The first and most difficult thing a new greenhouse worker mist be taught is greenhouse worker mist be taught is how to water properly.how to water properly.

Semiautomatic watering Semiautomatic watering methods:methods:

– Spray systems – deliver water Spray systems – deliver water through nozzles spaced at through nozzles spaced at intervals.intervals.

– Trickle systems – deliver water Trickle systems – deliver water through holes in plastic tubes.through holes in plastic tubes.

– Ooze tubes – plastic tubes rolled Ooze tubes – plastic tubes rolled between plants; water seeps between plants; water seeps through small holes.through small holes.

– Water loops – used for irrigating Water loops – used for irrigating container plants; use small rings of container plants; use small rings of plastic placed in containers.plastic placed in containers.

– Capillary mat – a mat of fibrous Capillary mat – a mat of fibrous material that is placed under plants; it material that is placed under plants; it is periodically flooded with nutrients is periodically flooded with nutrients which the plants will absorb.which the plants will absorb.

– Ebb and flood irrigation – water floods Ebb and flood irrigation – water floods a bench and then recedes into a tank.a bench and then recedes into a tank.

Capillary mat

Flood irrigation

Trickle system

Two ways fertilizer can be applied:Two ways fertilizer can be applied:– Dry fertilizersDry fertilizers– Water-soluble fertilizers/greenhouse Water-soluble fertilizers/greenhouse

watering system liquid.watering system liquid. The greenhouse watering system is The greenhouse watering system is

the most common means of applying the most common means of applying liquid fertilizer to crops.liquid fertilizer to crops.

Three types of systems Three types of systems used in applying liquid used in applying liquid

fertilizer:fertilizer:– Venturi proportioner – draws fertilizer Venturi proportioner – draws fertilizer

through a small tube that connects the through a small tube that connects the water hose to the fertilizer concentrate.water hose to the fertilizer concentrate.

– Positive displacement pump – maintains Positive displacement pump – maintains a uniform proportion of fertilizer to water a uniform proportion of fertilizer to water ratio, regardless of the water pressure or ratio, regardless of the water pressure or rate of flow.rate of flow.

– Eductor –places the fertilizer concentrate Eductor –places the fertilizer concentrate in a pliable bag surrounded by water in a pliable bag surrounded by water pressure; as the pressure increases it pressure; as the pressure increases it forces the fertilizer through a metering forces the fertilizer through a metering system and into the water line.system and into the water line.

The amount of fertilizer applied per The amount of fertilizer applied per application depends on strength of application depends on strength of the concentrate, dilution ratio of the the concentrate, dilution ratio of the injector, and the amount of water.injector, and the amount of water.

Greenhouse fertilizers are measured Greenhouse fertilizers are measured by the number of parts of nutrients to by the number of parts of nutrients to a million parts of water, or ppm, part a million parts of water, or ppm, part per million.per million.

PPM is determined by percent of PPM is determined by percent of element in fertilizer X 75.element in fertilizer X 75.

Growth retardants are sometimes Growth retardants are sometimes needed because plants get too tall to needed because plants get too tall to make desirable potted plants.make desirable potted plants.

The conditions of high temperature The conditions of high temperature and high humidity, coupled with close and high humidity, coupled with close spacing of a monoculture, make pest spacing of a monoculture, make pest control necessary in greenhouse control necessary in greenhouse production.production.

Exclusion – prevent pests from becoming Exclusion – prevent pests from becoming established in greenhouse.established in greenhouse.

Eradication – remove or eradicate pests.Eradication – remove or eradicate pests. Protection – place a barrier between crops Protection – place a barrier between crops

and pests.and pests. Resistance – selection of a resistant Resistance – selection of a resistant

variety of plant.variety of plant. No spray, dust, or fumigant kill 100% of No spray, dust, or fumigant kill 100% of

the pest population.the pest population.

Pest control in greenhouses Pest control in greenhouses is complicated by two is complicated by two

factors:factors:– Complex life cycle of many insects Complex life cycle of many insects

and some fungi that allows them to and some fungi that allows them to be unaffected by many chemical be unaffected by many chemical pesticides throughout much of pesticides throughout much of their lives.their lives.

– The rapid development of The rapid development of resistance to particular pesticides resistance to particular pesticides that characterize some pests, that characterize some pests, especially hosts.especially hosts.

To avoid the buildup of resistant pest To avoid the buildup of resistant pest populations, a grower must rotate populations, a grower must rotate the choice of pesticides frequently.the choice of pesticides frequently.

Ways greenhouse growers Ways greenhouse growers apply chemical pesticides:apply chemical pesticides:

– Systemics – remain in the plant and kill Systemics – remain in the plant and kill the pest when it arrives. Applied as a soil the pest when it arrives. Applied as a soil drench or as foliar sprays.drench or as foliar sprays.

– Sprays – material is mixed with water in Sprays – material is mixed with water in a hydroulic sprayer and applied to the a hydroulic sprayer and applied to the foliage.foliage.

– Dusts – covers large areas of crops Dusts – covers large areas of crops quickly and less expensively than sprays.quickly and less expensively than sprays.

– Aerosol bombs – material is packaged in Aerosol bombs – material is packaged in a container with a propellant liquid or a container with a propellant liquid or gas.gas.

– Smoke fumigants – pesticide is Smoke fumigants – pesticide is packaged with a smoke producing packaged with a smoke producing material that disperses the pesticide.material that disperses the pesticide.

– Steam line vaporizers- pesticide is Steam line vaporizers- pesticide is painted onto cold steam lines and the painted onto cold steam lines and the steam is turned on.steam is turned on.

– Foggers – the grower mixes the Foggers – the grower mixes the pesticides in an oil solvent and fills pesticides in an oil solvent and fills the fogger which heats and disperses the fogger which heats and disperses the pesticide.the pesticide.

– Misters – the pesticide is mixed with a Misters – the pesticide is mixed with a solvent that evaporates quickly once solvent that evaporates quickly once out of the mister.out of the mister.

Safe application of pesticides in the greenhouse Safe application of pesticides in the greenhouse or elsewhere requires an understanding that:or elsewhere requires an understanding that:– Health of the plant is more important than Health of the plant is more important than

killing the pest.killing the pest.– Health of the greenhouse staff and consumer Health of the greenhouse staff and consumer

are more important than the crops or pests.are more important than the crops or pests. The first rule of safe pesticide use is that The first rule of safe pesticide use is that

people are more important than plants or pests.people are more important than plants or pests.

Integrated pest management (IPM) Integrated pest management (IPM) uses methods other than just uses methods other than just pesticides to protect plants. It uses pesticides to protect plants. It uses temperature and humidity control, temperature and humidity control, resistant varieties, screens and other resistant varieties, screens and other barriers, monitoring devices, barriers, monitoring devices, predatory insects, and pesticides to predatory insects, and pesticides to keep problems down.keep problems down.

The region is important when The region is important when selecting crops to grow. Different selecting crops to grow. Different regions have different temperatures regions have different temperatures and different natural pests. A plant and different natural pests. A plant may not respond well to pests that it may not respond well to pests that it has never encountered before, or it has never encountered before, or it may not survive in the wrong may not survive in the wrong climate.climate.