Requirements for Plant Growth

Plants require certain environment for optimum growth

In greenhouse one must maintain best environment for growth

Plant Media

•Soil–Sand–Silt–Clay–Organic Matter

Water

•Water•1. Gravitational Water (held by gravity)–Drains away–Soils with large pores lose water fastest

Water

•2. Capillary Water–Held against gravity in pores

–Held in thin film around particles

–Soil particles are electrically charged

Planting Media Mixes

•Advantages to soil less media–1. Mix is uniform–2. Sterile–3. Lighter in weight–4. Good moisture retention and drainage

Planting Media Mixes

•Disadvantages to soil less media–1. Lightweight–2. Minerals missing must be added

–3. Hard to transplant into soil

Planting Media Mixes

•Content of mixes–Perlite: volcanic origin

•Improves aeration•Small white pebbles

Media contents

–Vermiculite: yellow expanded mineral•Increases moisture holding capacity

Media Contents

•Sphagnum Moss: acid bog plants–Holds moisture, very light

•Peat Moss: decomposed vegetation–Holds moisture

Media Contents

•Tree Bark–Improves aeration

Plant Food

•Water: most important–Plant weight = 90% water–1% of water absorbed is used, rest is lost through leaves

Plant Food

•Water:–Transpiration: Water lost through stems and leaves•Natural air conditioning

Plant Food

•Major Nutrients–N, P, K–Numbers in fertilizer are those three in order so…•10-15-20 = 10% N, 15% P, and 20% K

Plant Food

•Nitrogen–Makes dark green color–Too much is a problem

•Lowers disease resistance•Weakens stem

–“leaching” is a problem

Plant Food

•Phosphorus–Affects maturity–Cell division–Roots –Insufficient = purplish color on underside of leaves

Plant Food

•Potassium–Affects Photosynthesis–Root System–Insufficient = also purplish color, much more rare than P

Soil Acidity

•0-14•0 = acidic•14= basic•7 neutral•Acid = add lime•Basic = add sulfur

Other Factors•Temperature 65-70 F•Light Short and Long Day Plants

•Plant Diseases –Biggest scares to greenhouses

•Insects our biggest problem•Gases