page 71
GROWING MEDIA FOR CONTAINERS

 

WHY PURE FIELD SOILS ARE NOT USED IN CONTAINER PRODUCTION
1) packs too much, which:

    a) decreases total pore space, esp. large pores

    b) decreases aeration

    c) decreases drainage

2) must sterilize for disease and weed seeds

3) heavy - increases shipping costs and heavy to manually handle

4) hard to obtain good supply in many areas
 
 

GROWING MEDIA
Most container production uses specially prepared mixes called growing media, artificial media, soilless media or potting soils, which are made from various organic and inorganic growing medium amendments.  The highest quality peat moss is sphagnum peat moss.  All the organic amendments, except peat moss, must be composted before use. 
 
 

Organic Amendments
Inorganic Amendments
peat moss
bark
coir
sawdust or wood shavings
cedar chips 
rice hulls
bagasse
cotton gin trash
municipal compost or processed sludge
sand
vermiculite
perlite
styrofoam
calcined clay or haydite 
rice hull ash
rock wool

 

Typical Growing Medium Should Contain:
50-75% organic amendments - usually sphagnum peat moss, composted bark or coir 
25-50% inorganic amendments - usually vermiculite, perlite, sand or styrofoam
plus: lime, starter fertilizer and sometimes a wetting agent and gypsum