Media Function 1. Holds plant nutrients 2. Provide oxygen to root zone 3. Hold Moisture 4. Provide support

Desired properties of Root Media 1. Organic matter stability—must be partially decomposed to prevent heat buildup and shrinkage 2. Adequate Carbon:Nitrogen Ratio— microorganism utilize both C and microorganism utilize both C and N. Ideal C:N ratio is 30:1

Desired Properties of Media 3. Bulk Density---relates to weight of media and support of plant. Acceptable range is 40-75# per cubic feet. 4. Moisture Retention and Aeration— After watering, 10-20% of the medium should be occupied by air and 30-50% by water.

Desired Properties of Media 5. Cation Exchange Capacity— refers to nutrient holding ability of the media. CEC is a measure of how many electrically charged particles are held by the media expressed in milliequivalents per 100 grams. Levels of me per 100 g is desirable.

Desired Properties of Media 6. pH---level of acidity and alkalinity. Level will govern nutrient available to the plant. 7. Fertilizer content—most commercial mixes contain some nutrients. P and lime need to be included. P because most soil-less mixes don’t have it and lime to adjust pH.

Desired properties of media 8. Mixability—able to be mixed uniformily. 9. Economically—Media components are becoming more expensive. EX: Pine Bark Fines = $14.55 yd Vermiculite = $99.75 yd Peat Moss = $78.00 yd Pro-Mix BX = $87.00 yd

Desired properties of media 10. Freedom from pest—if not sterilized, need to be heated at 180 degree F for 30 min. 11. Available---where are sources for the product. Most bag components can be purchased from suppliers but pine bark must be secured from local vendors.

Media Suppliers Hummert International Park Seed Wholesale Ball Seed Company

Pine Bark Vendors Eakes Nursery Materials Seminary, MS Accardo Products Covington, LA Phillips Bark Wiggins, MS

Media Components 1. Vermiculite 1. Vermiculite

Vermiculite This is an ore mined in the US and Africa. The ore has a bulk density of 55-65#/cu ft but drops to 7-10#/cu foot after it has been heated and crushed. It has high water holding capacity because of expandable sheets of Si and Al. CEC of me/100g and fert. Elements of K, Mg and Ca. Most Amer. Types are neutral in pH.

Perlite

Perlite Perlite is a siliceous volcanic rock which is crushed and heated at 1800 degrees F where it expands and forms white particles. Water is adsorbed (adheres) on particles and not absorbed. Perlite is sterile, has no CEC with a pH value of 7.5.

Bark Bark fines are bark chips that have been hammermilled and screened to 1/8-1/4” size. Bark should be composted since fresh bark can have C:N ratios of 300:1 which will cause N tieup, high heat and unavailable nutrients to the plant.

Peat 1. Moss Peat—light tan to brown in color. Least decomposed peat formed from sphaghum or hypnum peat. Have N content of %. Decomposes slowly. Holds 60% of its volume in water and pH of Sphagnum peat—most acid of all peats with pH levels of

Peat 3. Reed-sedge Peat—brown to reddish brown in color. Formed from swamp plants including reeds and sedges, marsh grasses and cattails. Generally is higher decomposed than the first two. The water holding capacity is less than sphagnum peat with pH levels of

Peat 4. Peat Humus—Most composed peat material. Not used very much in horticultural enterprises. It has a dark brown to black color with very acidic pH’s. It often also contains silt and clay in it’s makeup.

Sand Sand provides good aeration and drainagae as well as bulk density to a mix. Sand is made from quartz rock and sharp sand should be used. Sand has no CEC, neutral pH and no water holding capacity. River sand or fill sand should not be used in commercial potting mixes.

Calcined Clays These are aggegates of clay particles that are heated at high temperatures. They provide excellent aeration and drainage properties. The pH of these products varies from and they have CEC ranges of 6-21 me/100 g. EX: Terragreen or Turface $11.00 per 50 # bag $11.00 per 50 # bag

Misc. Media Components Bagasse—by product of sugarcane industry Sawdust—by product of mills Rice hulls—rice coverings from mill Cotton gin trash Pecan shells, crushed Earthworm casing Coffee ground chafe

Misc. Media Components All of these materials have unique characteristics but they have to follow the guidelines set by being desirable. In many cases, they may have the chemical properties but the availabilty and quantities may be an issue.

Commercial Prepared Mixes There are many types of commercial bag mixes that offer a grower an outlet to purchase. These mixes provide the grower with a quick alternative to storing all media components and the expense of mixing each batch. It should be noted that in some cases, this advantage may be more costly.

Pro-Mix

Pro-Mix Made by Premier Horticulture Company. There are many Pro-Mix formulations that the company sells. One of the most common is Pro-Mix BX, a “General Purpose” peat-based growing medium with perlite and vermiculite used for a wide range of plants. It is packaged in a compressed 3.8 that loosen to 7 cu ft.

Fafard Growing Mix

Fafard This company is in Massachusetts. All Fafard media contains choice New Brunswick sphagnum peat moss and, depending on the mix, No. 3 vermiculite and horticultural grade perlite. pH values are adjusted to with fine dolomite and calcitic limestone. There are a wide assortment of formulations.

Metro-Mix

Metro-Mix Made by Sun Gro Horticulture with many formulations to chose. All are peat based with different percentages of bark, perlite and vermiculite

Redi-Earth

Redi-Earth Also made by Sun Grow. This material is mostly for seed germination, plug trays, rooting medium and seedling development. All particle sizes are very small. This formulation is based upon the Cornel Peat-Lite Mix. It contains peat moss and vermiculite with a wetting agent and starter nutrient charge.

Jiffy-Mix

Jiffy-Mix Made by Jiffy International Co., the same company that produces Jiffy peat pots, Jiffy 7/9’s compressed peat pellets. This is also mainly a medium used for seed germination, plugs and propagation. A formulation called Jiffy-Mix Plus adds additional nutrients to the mix.