Greenhouse Crop Management Sheila Dunning Commercial Horticulture

Production Needs Media Irrigation Fertilization Pest Management Best Management Practices

Soilless Media Good water retention, yet well drained Uniform enough to allow for standardized fertilization and irrigation Free from harmful pathogens, insects, nematodes and weeds Low in salts, but good exchange capacity Biologically and chemically stable

Media Factors Solids Pore Space Drainage Water Holding Capacity pH

Air, Water and Media Pore space Large pores allow air spaces to be filled with water Most mixes contain 10%-30% air following irrigation Compaction of soil reduces large pores Less available water and air Decreases drainage Drainage Small pores hold water longer Shorter columns of media hold water longer, drain more slowly and contain less air (Azalea vs. standard style pots) Water holding capacity Soilless mix should hold 60%-70% water after drainage

Media Components Sphagnum moss –Dehydrated remains of acid-bog plants –Absorbs 10-20X its weight in water Bark –Bi-product of pulp, paper and plywood industries –Requires N supplements due to depletion during decomposition Sand –Medium and course particles provide drainage –Inexpensive, but heavy Perlite –Puffed volcanic mineral –Increases aeration and drainage Vermiculite –Baked mineral –Improves water holding capacity & exchange capacity

Commonly Used Mixtures 2:1:1 Peat, Perlite, Vermiculite 2:1:1 Peat, Bark, Sand 2:1:1 Peat, Bark, Perlite 3:1:1 Peat, Perlite, Vermiculite 3:1:1 Peat, Bark, Sand

pH Affected by: Media components Irrigation water quality Fertilizers with nitrates Influences availability of nutrients Measurements should be taken when soil is at maximum water capacity Optimum – Most common pH buffer 2-8 pounds of dolomitic lime/ cubic yard of media

Container Media Test IFAS Form 2674 pH, EC Nitrate, Nitrite, Phosphorus, Potassium Ca, Mg $6.00

Irrigation Delivery methods –Overhead sprinklers, drip system, by hand Factors –Condition of media –Water quality Frequency Amount

Irrigation Drip system – least wasteful and reduces disease potential Most common emitters – 1-3 gal/hr Delivery rate should prevent overflowing container Correct pH of water to and monitor salts Frequency dependent on season and media condition Components become hydrophobic if allowed to dry May require wetting agents to rehydrate Never pot in excessively dry mix Apply 10%-15% more water than the container will hold Facilitates leaching with each irrigation Reduces salt accumulation

Irrigation Water Analysis IFAS Form 2673-A pH, EC Ca, Mg, Na, Fe, Cl $7.00

Fertilizer Primary application of complete liquid most common analysis ppm N (1-3 # per 100 gal) Supplement media before potting Time released complete Micronutrients pH buffers Test for salts EC < 2.0 millimhos/cc Monitor for deficiencies

Macronutrients Micronutrients Carbon C Hydrogen H Oxygen O Nitrogen N Phosphorus P Potassium K Sulfur S Calcium Ca Magnesium Mg Iron Fe Manganese Mn Boron Bo Copper Cu Zinc Zn Molybdenum Mo Chlorine Cl Cobalt Co Nickel Ni

Calibrachoa Soil pH Acidic Alkaline Degree of soil acidity or alkalinity Affects nutrient availability Affects plant performanc e

Pest Management Weeds Physical removal at first sign No pre-emergents labeled for greenhouse Diseases Hours of extended wetness Insects Monitor with sticky traps

Insects Aphids Spider MitesThrip Whitefly

Government or Agriculture? Different rules for chemical application inside and outside of greenhouse

Best Management Practices Start with clean material Maintain facility equipment Test media and water regularly Practice sanitation Eliminate pests surrounding greenhouse Utilize Integrated Pest Management Keep accurate records

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