Greenhouse Growing Media and Plant Fertilization Mr. Wilson Greenhouse Uintah High School

Unit Objectives Examine the components and properties of growing media. Describe the components of growing media. Describe the functions of growing media. Determine desirable properties of growing media. Evaluate the advantages and disadvantages of soilless media. Investigate chemical characteristics of growing media. Interpret pH test results of a growing media sample.

Additional Objectives Supply nutrients to greenhouse crops. Explain plant nutrition. Describe pH and how it is modified. Describe the components of a fertilizer. Explain the methods of applying fertilizers to horticulture crops. Demonstrate proper techniques for sampling growing media. Test and determine pH level of various growing media.

TERMS Aeration – the presence of air Growing medium – material used for plant growth Hydroponics – growing plants w/o “soil” Leach – to remove by percolation Pore spaces – voids for water or air holding Soil – outer layer of the earth suitable for plants Soilless medium – sterile product/s used for plants

What is growing media? The material that your plants grow in is called the “growing medium. Characteristics: Soil-less mix – usually doesn't contain soil Used to grow greenhouse and nursery plants Usually is pasteurized Usually purchased or made

Functions of Growing Media Growing medium has three main functions 1) Supply roots with nutrients, air, and water. 2) Allow for maximum root growth. 3) Physically support the plant. Anchor roots! Roots grow in the spaces between individual particles of soil.  Air and water also travel through these pore spaces.  Water is the medium that carries nutrients that plants need to fuel their growth, and air is needed for root growth and the health of soil microorganisms that help supply plants with nutrients.

Advantages of Soil less Mixes sterile lightweight good moisture retention and drainage free of weed seeds Designed for the plant type!

Disadvantages of Soil less Mixes light weight - pots tip in strong wind minor elements are missing transplants may not adjust well to new media

Which Makes the Best Growing Medium? Sand Peat Moss Field Soil Vermiculite Pearlite Water Gravel Find out from the class what they feel is the best medium. Question where “soil” is used for floriculture? Ask how they have purchased plants and what the medium was? Lead a discussion on what each sample contains that allows it to be used as a growing media.

What are the types of growing media used in greenhouse production? Is “soil” used? Soil – the earth’s outer crust is full of life! Bacteria Fungi Invertebrates Yes – we use field grown plants for some production. Outdoor production has problems of its own. Bacteria – fungi - …. Cut flower production can occur outside of a greenhouse. Some greenhouse production is in field soil.

What are the negatives of using “SOIL” for containers? Unknown history of: Pesticides pH Fertility level High shrink / swell Soil shrinks as it dries – forming cracks Higher disease probability Container medium must be sterile!! Container medium must be spongy! Can field soil be sterilized? Fumigants and steam can kill all life in the soil.

So what media should you use? Sand? Dries to quickly. Peat moss? Dries to slowly. Choir? Hard to get wetted. Water? To little air. Pearlite? To much air. Vermiculite? Pricey. Potting soil mixes? Just right. Many materials can be used – each has its own pitfalls Choir – coconut fibers that are hollow All material can be reduced in size and thereby its properties for a media In general, a combo of materials is used.

What effect does growing media have on plant growth? Supplying Nutrients Some media cannot hold essential elements for plants. Nutrients are leached out to rapidly. Stressed plants are prone to disease and insect damage – increasing loss. Reduced growth = lower returns Choosing the right growing media for floriculture crops is very important. The media can affect the amount of nutrients that are available for the plants, the presence of water, and the ease of growth plants.

What effect does growing media have on plant growth? Supplying Air As air is reduced, plant stress increases. Roots need oxygen and water – both in moderation. Increasing stress increases pest susceptibility and profit loss The ability of the growing media to drain water is very important for plant growth. Plant roots need oxygen to function properly and if the growing media is saturated with water, the plant roots will die due to lack of oxygen. The roots may also rot. Excess water in the growing media can also lead to insect problems.

What effect does growing media have on plant growth? Uniformity Large scale production demands that all plants perform equally. This is only possible if all plants get equal inputs from a uniform media. In the production of floriculture crops, it is important to use a growing medium that is uniform. With a uniform mix, watering, fertilizing, and transplanting schedules can be developed in order to insure even growth of the crop.

Content of commercial mixes Soilless mixes contain various combinations of the following materials.

Perlite improves aeration of volcanic origin

Spahgnum Moss Dehydrated remains of acid bog plants Used to cover seeds because it is lightweight, controls disease, and holds moisture.

Peat Moss Partially decomposed underwater vegetation. Holds moisture well Low in nutrients

Vermiculite Exploded Mica Improves aeration Holds moisture very well

Limestone Raises pH You would not want to use this in our area’s natural soils.

Plant nutrients and fertilizers Plants do not eat! Not Food! Water Elements

Water Water is the most important plant nutrient Makes up 90% of the plants weight Water transports the other elements around the plant

Elements divided into two groups, macro and micro Major elements (macro) Nitrogen – N Phosphorus – P Potassium - K

minor elements (micro) Calcium - Ca Magnesium - mg Sulfur - S Iron - Fe

minor elements (micro) Manganese - Mn Boron - B Copper - Cu Zinc - Zn

Plant requirements large amounts of major elements relatively small amounts of minor elements

A way to remember the Nutrients required for plant growth. C.B. HOPKiNS CaFe Mighty good Closed Monday Morning See You Zen! Other elements for plants? Not essential but help plant growth:Se, Ni, Co, Na??

Commercial fertilizers shows % or pounds per cwt. (100#) of the three major elements in large numbers on the container or bag.

Commercial fertilizers 5-10-5 5% N, 10% P, 5% K remaining 80% is filler NP&K are always listed in that order.

Soil tests determine amount of elements needed for various plants. https://www.youtube.com/watch?v=3YuA20kZ1EA

How to take a soil sample Take random samples from the area to represent the area you want to test. Mix all samples together. Take a sample from the mix of about 16oz of soil. Complete soil test info sheet. Mail to a reputable lab. Analyze results and make decisions.

Nitrogen has most noticeable effect on plants encourages above ground vegetative growth regulates use of other elements

Too much Nitrogen lower disease resistance weaken stem because of long soft growth lower fruit quality

Too much Nitrogen delay maturity increase winter damage to plants

Not enough Nitrogen yellow or light green color stunted root and top growth

N lost easily from soil leaching - being filtered down through soil with water not held by soil particles, dissolved in water O.M. holds insoluble N for slow release

Nitrogen Deficiency in Corn

Phosphorous held tightly by soil particles not easily leached

Phosphorous effects plants in several ways encourage cell division flowers and seeds don’t form without it hastens maturity, offsetting quick growth caused by N.

Phosphorous encourage root growth makes K more available increase disease resistance improves quality of grain, root and fruit crops

Insufficient P purple color on underside of leaf reduced flower fruit and seed production

Insufficient P susceptibility to cold injury susceptibility to plant diseases poor quality fruit and seeds

Potassium modifies both fast soft growth of N and early maturity of P is essential

Potassium increase disease resistance encourages healthy root systems essential for starch formation

Potassium development of chlorophyll efficient use of CO2

Insufficient K leaves appear dry and scorched with irregular yellow areas on the surface

Lime CaCO3- Calcium Carbonate acts as a plant food affects soil acidity – raises pH! soil acidity affects availability of plant food elements

Lime furnishes Calcium

pH measure of acidity or alkalinity pH scale - runs from 0 - 14 most plants grow best from 5.6-7.0

pH 7.0 is neutral pH of 7 or above is alkaline or basic pH below 7 is acidic

pH as numbers decrease, solution becomes more acidic. As numbers increase, solution becomes more basic or alkaline

How do we apply fertilizers? Apply granules Apply a liquid Applying liquid through water system Broadcast Band Container treatment

Above ground environment temperature some plants prefer cool weather some plants prefer warm weather

Temperature there are temperatures above and below which plants stop growth generally, plant growth rate increases as temps increase up to about 90 degrees

Light must be present before plants can manufacture food plants vary in light requirement effects flowering

Photoperiodism response to different periods of day and night in terms of growth and maturity

Photoperiodism short day plants chrysanthemum and Christmas Cactus bloom when days are short and nights are long

Photoperiodism long day plants lettuce and radishes bloom when days are long and nights are short

Photoperiodism day length indifferent do not depend on length of light or darkness African Violet and tomato

Phototropism plants appear to grow towards the sun or light source

Humidity moisture level of the air most plants grow best in 40-80% RH Relative Humidity

Humidity too high humidity may cause the spread of fungus diseases

Plant diseases and Insects reduce production lower fruit and vegetable quality

Soil composed of sand, silt, and clay, organic matter, living organisms, and pore spaces

Soil classified according to percentage of sand, silt, and clay they contain.

Soil Particles vary greatly in size sand - largest silt - medium clay - smallest

Sandy Soil silt and clay make up less than 20% by weight drain well little water holding capacity

Textural triangle

Clayey Soil must contain at least 30% clay holds more moisture than is good for plants poor drainage

Loamy Soil most desirable soil equal parts sand, silt and clay

Soil Profile consists of 3 basic layers topsoil subsoil soil bedrock

Topsoil represents depth normally plowed

Subsoil deep rooting plants send roots down into subsoil

Soil Improvement Drainage change soil structure add organic matter to encourage earth worms

Moisture retention adding organic matter (o.m.) sources of o.m. animal manure green manure - crop grown and plowed under to improve the soil

Sources of O.M. peat moss sawdust mulches - compost or wood chips

Mulches placed on the surface to help retain moisture reduce runoff and evaporation reduce weeds

Diseases plant resistant varieties chemicals soil pasteurization heat to 180 degrees F for 30 minutes.