Potting Soil and Media Horticulture I Ag 514

Potting Soil and Media Horticulture I Ag. 514

Terminology �Functions of plant media ◦ Soilless rooting material in which plants grow ◦ Provides a medium for rooting ◦ Provides a medium for nutrient supply �Nutrients are the substances roots absorb from soil water ◦ Anchor the plant

Types of Planting Media �Soilless �Liquid or artificial

Soil �Soil contains: ◦ Mineral matter (aka “rocks”) ◦ Organic matter (remnants of organisms) ◦ Water ◦ Air

Soil in Potting Mixes �Soil must be sterilized or pasteurized ◦ Sterilization – (above 180 degrees)killing all bacteria, weed seeds, insect eggs and larvae, and anything else that could effect plant growth ◦ Pasteurization – (160 to 180 degrees) killing a high enough level of harmful organisms �Heat or electric ◦ Protects plants from insects, disease, and invasive weeds

Soilless Media �Contains no soil �Is a combination of a variety of components: ◦ ◦ ◦ Vermiculite Perlite sphagnum peat moss Tree bark Dolomitic limestone (calcium carbonate) Slow release fertilizer

Vermiculite �Biotite mica that expands when exposed to high heat �Mined in South Africa, China, Brazil, and the eastern Appalachian chain of the U. S. �High moisture holding capacity

Perlite �Volcanic “glass”/silicate �When heated to softening, expands to twice its original volume �High moisture content �Provides aeration to soilless mixes

Sphagnum Moss �Sphagnum moss is the living moss found on top of peat bogs; it is used to line floral baskets and make wreaths �Is not used as a component of soilless mixes…it’s just pretty!!

(Sphagnum) Peat Moss �Used in potting mixes ◦ Dead material that accumulates in lower levels of peat bogs ◦ Used as a soil conditioner ◦ Used to cover seeds for germination ◦ High moisture retention ◦ Lightweight ◦ Increases soil acidity

Tree Bark �Usually pine or oak �Broken into small pieces �Used in containers and for mulching �Can increase mix acidity �Inexpensive filler for large containers

Dolomitic Limestone/ Calcium Carbonate �Decreases soil or potting mix acidity �Increases soil p. H �Often termed “liming” soil

p. H Scale �Amount of acidity or alkalinity in soil/soilless mix

p. H Scale in Simple Terms

Slow-release Fertilizers �Plant food made available to plants over a gradual length of time �Used in soilless mixes to provide nutrients

Factors to Look at When Selecting a Growing Medium �Chemical Factors ◦ Nutrient storage/supply capacity �Physical ◦ ◦ ◦ Factors Water holding capacity Aeration Anchorage/plant support Uniformity Shrinkage �Economic Factors ◦ Availability ◦ reproducibility

Soilless Media Advantages Disadvantages �Uniform mix �Sterile (no disease, insects, weed seeds, etc. ) �Lightweight �Good moisture retention and drainage �Characteristics are controllable �Container instability due to lightweight material �Low mineral content �Rooting problems when transplanting ◦ Roots won’t spread into soil unless extreme care is taken when transplanting