View Single Post
Old April 5, 2011   #3
fortyonenorth
Tomatovillian™
 
fortyonenorth's Avatar
 
Join Date: Jan 2010
Location: NW Indiana
Posts: 1,150
Default

Topsoil - nutrients for plants. Disadvantage - compacts. Inexpensive
heavy, generally does not drain well in a container

Composted manure - same as topsoil. Additional disadvantage - weeds.
yes, same disadvantages as topsoil. However, I've put an inch or two of composted manure on the very top of the potting mix (once it's settled) and it provides a good source of nutrients over time.

Mushroom compost - same as topsoil, even more nutrient-rich
mushroom compost is derived from the mushroom growing medium which is generally peat with added straw and lime. It is lighter than topsoil, is relatively inexpensive if purchased in bulk, but can be high PH, so be careful how much you add.

Peat - nutrients. Holds water. Compacts?
good water retention and a valuable ingredient of most mixes. No nutrient value and generally low pH.

Bark fines - aeration. Does this use up nitrogen though?
excellent ingredient that generally makes up at least 1/3 - 1/2 of my mixes. No nutrient value, good aeration. Pine bark fines will not tie-up nitrogen, but be careful of what you purchase, because I've seen bags of "fines" which actually include a fair proportion of shredded hardwood, which will tie-up N.

Vermiculite - aeration. Kind of expensive
perlite serves the same purpose and will hold up longer than vermiculite. Not sure about comparative price, but I get a very big bag of perlite for about $15

Other ingredients - ?????
Turface, Pros Choice and other calcined clay products, most often marketed for ball field conditioners, are excellent additions to potting mix. I get Pros Choice from a nearby John Deere Landscapes retailer, but I'm not certain of their distribution.
fortyonenorth is offline   Reply With Quote