Environmental Requirements for Good Plant Growth Unit 4 Environmental Requirements for Good Plant Growth

The Greatest Influence The greatest influence on plants Water Nutrition—16 elements from soil or fertilizers Medium—soil or soil substitute Temperature—growth influenced by heat (continued)

The Greatest Influence The greatest influence on plants Light—intensity of light affects photosynthesis Humidity—moisture level in the air Insects and disease—reduce production

Importance of Water Most of the water is contained in the cells (vacuoles) Necessary for photosynthesis to occur

Importance of Water Helps to transport nutrients and produces food throughout the plant. (Photosynthesis) Nutrients from the soil must be in a water in order for the plant to absorb them. (continued)

Importance of Water Water vapor evaporating from leaves cools the plant (Transpiration)

Inadequate Water Can stress plants Makes plants more susceptible to disease and pest. Slows the process of photosynthesis

Nutrition Plants require at least 16 elements from the soil or from fertilizers Nutrition is important to plant health and good growth In loam soils (sand, silt, clay), enough minor elements are available for satisfactory plant growth (continued)

Nutrition In soilless mixes (vermiculite, perlite), minor elements may be deficient The major elements nitrogen, phosphorus, and potassium are needed most often (N-P-K)(Fertilizers)

Temperature Plant growth is greatly influenced by heat (continued)

Temperature Plant growth increases as temperature increases up to 86°F (31°C) for most plants Cooling plants below their best growing temperature causes reduced growth.

Soil Chemical use—causes loss of native soil fungi and beneficial microorganisms Made up of sand, silt, clay, organic matter, living organisms Consists of three layers Topsoil, subsoil and soil bedrock

Three Types of Soil Sandy Clay Loamy Silt and clay make up less than 20% Clay At least 30% clay Loamy Best soil is equal parts of sand, silt, and clay

Soil Improvement Drainage and aeration—add organic matter Add lime and gypsum (calcium sulfate) Raise plant beds (continued)

Soil Improvement Moisture retention—add organic matter Animal manures Mulches Peat moss Fertilizers

Soil Deficiencies Nutritional Deficiencies Pests and Diseases Nitrogen—yellow or pale green leaves Phosphorous—purple color underside of the leaves Pests and Diseases Examples— insects, root rot, fungus

Content of Soilless Mixes Perlite Sphagnum moss Peat moss Vermiculite Limestone Tree bark (continued)

Content of Soilless Mixes Slow-release fertilizers

Plant Food and Fertilizers Nitrogen: has the most noticeable effects on plants (green appearance) (continued)

Plant Food and Fertilizers Phosphorous—encourages plant cell division, increases resistance to disease and encourages strong root growth Potassium

Soil Acidity (pH) To lower pH in alkali soils Add sulfur, iron sulfate, or aluminum sulfate (continued)

Soil Acidity (pH) Lime: raises pH levels activates soil organisms encourages the release of food

Plant Hardiness Zones 12 zones—based on the average number of days the daily high temperature reaches or exceeds 86°F Use zones as a guide of plant adaptability Factors used to determine plant choice include rainfall, wind, sun, humidity, snow cover

Wrap up For successful plant growth: It is extremely important to consider the plant environment both underground and aboveground Soil conditions and soilless mixes must match plant needs (continued)

Wrap up Plant medium must be evaluated in terms of soil, pH, drainage, and fertility Soilless mixes specially formulated for most plants grown in containers are now available There is little, if any, need to mix your own anymore (continued)

Wrap up Important aboveground factors Temperature, sun, and wind exposure Select only plants adapted to the environment they will be placed in