Monday, September 26, 2011

Make Your Own Planting Mix

Note: for all recipes, coir can be substituted for peat moss.


The Rodale Instute Mix (organic):
Finely screened compost  4 parts
Peat Moss  2 parts
Perlite  1 part
Vermiculite 1 part


Another organic mix (from the book, "Rodale Organic Gardening Solutions"):

shredded peat moss  1 bushel
perlite or vermiculite  1 bushel
ground limestone  1/2 cup
bloodmeal  1 cup
colloidal phosphate  1 cup
greensand   1 cup

(1 bushel = 1.24 cubic feet)

Container mix for herbaceous and woody ornamentals

Equal parts by volume of:
coarse sand
peat moss or milled pine bark 


Cornell University Modified Peat-Lite Planting Mix:(especially good for seedlings)
for large jobs (1 part=one full wheelbarrow, about 4.5 cu. ft.)
Peat Moss 2 parts
Perlite  1 part
Vermiculite  1 part
Dolomitic Lime (raises pH) 4 cups
Superphosphate (0-20-0) 5 cups
Osmocote or other slow release fertilizer (19-6-12)  8 cups

for small jobs (1 part= a 32 oz. coffee can)
Peat Moss 2 parts
Perlite  1 part
Vermiculite  1 part
Dolomitic Lime (raises pH) 1 tsp.
Superphosphate (0-20-0) 2 tsp.
Osmocote or other slow release fertilizer (19-6-12)  1 Tbs.


Note: when using peat moss, pre-moisten the peat moss to aid moisture retention. In a hose-end sprayer, put one tablespoon liquid dish detergent in the jar. Set sprayer to mix one tablespoon per gallon of water. Thoroughly water the peat moss with this solution before mixing with other ingredients.


Purchasing a commercial potting soil or planting mix?

• Select mixes high in bark, forest materials, or spaghnum peat with vermiculite or perlite.

• Thoroughly leach any potting soil before placing seed or plant material in the mix. Leaching will reduce soluble salts to acceptable levels in most mixes.

•Fertilize with a soluble fertilizer according to manufacturer's directions within two weeks after plants are growing in the new potting/planting mix or potting soil. This will replace leached nutrients and those taken up by the plants.


The difference between a potting/planting mix and potting soil?
There are no hard and fast rules. Ask 100 experts, you may get 100 different answers. Generally speaking, if the bag says "soil", it probably contains soil and sand, along with ingredients such as perlite, vermiculite, peat moss or bark.

When you buy a garden product with the word "soil" - especially at a low price - you are increasing the chances of buying someone else's problems: a package that contains weed seeds, nematodes, fungal diseases, heavy clay, sludge.
Your best bet, as stated above: choose a product high in bark, forest materials, or spaghnum peat with vermiculite or perlite.


  1. For my raised beds I use a combination of peat moss, sand, and Amend. I think it works fine for me. Do you have any suggestions?

  2. If it works for you, fine! Many planting mix recipes call for sand; I prefer to use something a bit more lightweight, like perlite.

  3. I have question on The Rodale Instute Mix (organic):
    Finely screened compost 4 parts
    Peat Moss 2 parts
    Perlite 1 part
    Vermiculite 1 part

    Should I buy COmpost from store like Home Depot they sell compost blend for about $ 1.05 / bag ?

  4. Why are you citing all these different mixes and not citing and/or using UC mixes... especially those cited that raise the pH?


  5. The best compost is the compost you make yourself. I am wary of bagged compost products, because you can't see if it is truly "finely screened". You should not be able to recognize any of the original ingredients when you buy compost. Also, be wary of compost from municipal recycling centers. lawn grasses that were treated with post emergent weed control products sometimes take two years to break down. Organic compost is your best bet when buying it. Also, do a ph test (cheap, easy) of any compost before you buy it in bulk.

  6. As far as I can determine, the UC planting mix recipes contain items I am a bit leery of, including copper sulfate, magnesium sulfate, ferrous sulfate, zinc sulfate, potassium nitrate, and more. Check out these soil mixes from UC Riverside for more info: