Saturday, April 13, 2024

Make Your Own Planting Mix (updated 2024)

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)

Seedling mixes for starting transplants

Seed mix (Biernbaum, 2001)

  • 2 parts screened compost
  • 4 parts sphagnum peat
  • 1 part perlite
  • 1 part vermiculite
  • Lime as needed to adjust pH to 6

Seed mix - standard soilless (Biernbaum, 2001)

  • 50–75% sphagnum peat
  • 25–50% vermiculite
  • 5 lbs of ground or superfine dolomitic lime per cubic yard of mix
  • Blood meal, rock phosphate, and greensand at 5 to 10 lbs per cubic yard

Organic seedling mix (Biernbaum, 2001)

  • 10 gallon of 2 year old leaf mold, sifted
  • 10 gallons of sifted compost
  • 5–10 gallons of sphagnum peat
  • 5 gallons of perlite
  • 5 gallons of coarse river sand
  • 3 cups blood meal
  • 6 cups bone meal

Soilless potting mix (used by Windsor Organic Research on Transition project, E. Zaborski)

  • 1 part compost
  • 1 part vermiculite
  • 1 part peat moss

Screened with ¼ inch screen to mix together. Per 1 gallon mix add:

  • 0.6 oz blood meal (17.01 grams)
  • 0.4 oz clay phosphate (11.34 grams)
  • 0.4 oz greensand (11.34 grams)

Soil-based seedling mix (Hamilton, 1993)

  • 2 parts loam (stacked turf to kill any weed seed and disease)
  • 2 parts sphagnum peat
  • 2 parts coarse grit (sand)
  • 30 g or 1 oz lime for each 2 gallon bucket (9 liters)
  • 60 g or 1 oz blood meal for each 2 gallon bucket (9 liters)

Organic potting mix (credited to Eliot Coleman in Kuepper, 2004).

  • 1 part sphagnum peat
  • 1 part peat humus (short fiber)
  • 1 part compost
  • 1 part sharp sand (builder's)

to every 80 quarts of this add:

  • 1 cup greensand
  • 1 cup colloidal phosphate
  • 1½–2 cups crabmeal or blood meal
  • ½ cup lime

Soil block mix (Kuepper, 2004; adapted from Coleman, 1995)

  • 3 buckets (standard 10-qt. bucket) brown peat
  • ½ cup lime (mix well)
  • 2 buckets coarse sand or perlite
  • 3 cups base fertilizer (blood meal, colloidal phosphate, and greensand mixed together in equal parts)
  • 1 bucket soil
  • 2 buckets compost

Seedling mix for soil blocks or seedling flats (from John Greenier of Stoughton, WI in Kuepper, 2004)

  • 2 3-gal. buckets Sphagnum peat moss
  • ¼ cup lime
  • 1½ cups fertility mix (below)
  • 1½ buckets vermiculite
  • 1½ buckets compost

Fertility mix: 

  • 2 cups colloidal (rock) phosphate
  • 2 cups greensand
  • 2 cups blood meal
  • ½ cup bone meal
  • ¼ cup kelp meal

Directions for mixing:

  1. Add peat to cement mixer or mixing barrel.
  2. Spread the lime and fertility mix over the peat.
  3. Mix these ingredients thoroughly.
  4. Add the compost and vermiculite and mix well again.
  5. When done, examine the distribution of vermiculite to ensure that it has been mixed in evenly.

Note that all bulk ingredients should be screened through 1/4 inch hardware cloth. Well matured, manure-based compost should be used (avoid poultry manure and wood-chip bedding).

Mixes for larger plants or containers

These mixes require the addition of mined nutrients from natural sources.

Cornell Organic Substitute for Classic Mix (as modified by Biernbaum, 2001)

  • ½ cu yd. sphagnum peat
  • ½ cu yd vermiculite
  • 5 lbs ground limestone
  • 2–4 lbs bone meal
  • 5 lbs blood meal

Check out all the information about potting mixes for Certified Organic Production at the NCAT Sustainable Agriculture Project Website


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 forest materials (especially for woody plants), or peat/coir with vermiculite or perlite (for herbaceous or non-woody plants).

Monday, October 19, 2020

Fall and Winter Tomatoes...From Your Greenhouse


506 Bush Tomatoes on New Year's Day
If you really want to demonstrate to your friends what a great investment your greenhouse is, nothing beats serving them home grown tomatoes...on New Year's Day.

Here's What You'll Need to Grow Greenhouse Tomatoes for the Winter and Spring:

A greenhouse or an indoor area with lots of light and heat. On line, check out the selection at Washington State-based Charley's Greenhouse. Also, check out the Sturdi-Built greenhouses of Portland, Oregon. Here in Northern California, there's Greenhouse Megastore in West Sacramento.

The Right Tomato. For the typical hobby greenhouse (8x5, 8x10, 8x12), cool season "determinate" tomatoes are best. These tend to be fairly compact plants (under 4 feet tall) that do not put on lots of growth after they set fruit. Determinate tomatoes usually ripen at the same time; so, choose several tomatoes that will ripen at different times, going from seed to fruit in 50-70 days. To minimize disease problems, choose tomatoes that have "built-in" disease resistance. These will have the letters "V" (verticillium wilt-resistant), "F" (fusarium wilt) "N" (nematodes), "T" (tobacco mosaic virus) and "A" (alternaria fungus) after the variety name of the tomato.

"Warm Greenhouse" or indoor room. This is one that maintains a nighttime temperature range of 55-70 degrees, preferably above 60 degrees for tomatoes. Daytime temperatures should range from 75-85 degrees. A heater, in conjunction with a thermostatically controlled vent fan, can easily provide that temperature range here in the Valley and foothills.

Sunlight. Tomatoes need full sun, at least six hours of direct sun a day. Try to position your greenhouse so that it can take best advantage of the low angle of the sun during the cold months, making sure the building isn't shaded by any evergreen trees or other structures.

Artificial light. Because of the lower intensity of the sun and the persistence of valley fog and low clouds during the winter, you will need a lighting system to supplement any natural light. Although there are many artificial lighting systems available, fluorescent lights are the most economical. Use four, 40-watt, 48-inch long fluorescent tubes side by side, keeping them 8-12 inches above the plants. Although standard "shop lights" are OK, investing in Gro-Lux wide spectrum fluorescent tubes will give your tomatoes more of the light spectrum that they can use. For the latest in grow light technology, including LED's, check this page at 
Charley's Greenhouse.  

Water. Although the cooler temperatures of the fall and winter will cut down on the amount of water that tomatoes need, a drip system connected to a timer will insure that the plants get the moisture they need. Four to eight gallons of water per week per plant should be plenty.

Soil. Planting directly into the ground of the greenhouse is OK, as long as the soil drains readily, has been amended with organic matter and isn't compacted. Building raised beds into the floor of your greenhouse works best. Make the sides of the raised bed 8-16 inches high, and at least 18 inches wide. The bed can be framed by a number of things, including untreated wood, blocks, bricks, or stacked old tires. Growing tomatoes indoors in plastic 5-gallon or 15 gallon pots works well, too. There are a lot of good container soil mixes on the market for tomatoes and vegetables, including Gardner & BloomeRecipe 420Black GoldDr. Earth and Fox Farms.

Hydroponic Systems. The technology for these has changed radically since I last used one, decades ago. Check with your local hydroponics store or nursery for more information about the latest and greatest.

Fertilizer. Because plants tend to slow down their growth in the colder months, cut your dosage of your favorite tomato fertilizer by half. For example, if the directions for a water-soluble fertilizer say to add 1 tablespoon per gallon of water, pour that same tablespoon into 2 gallons of water during the winter feeding periods. A once-a-month application should be plenty.

A Pollinator. In nature, bees and wind do most of the tomato pollination in the home garden. In the greenhouse, you can accomplish the same task by either gently shaking or holding an electric toothbrush (or similar device) next to the plant; twirling a small brush inside a tomato flower will transfer the pollen.

A Fan. A gentle breeze blowing across the plants for several hours a day aids pollination and helps strengthen the plants' main stems. Air movement also reduces the threat of fungal diseases.

 Some greenhouse tomato variety suggestions for the colder months:

Bush Early Girl VFFNT Hybrid. A bushy plant that produces 6-7 oz. fruit. Determinate, 54 days.

Bush Beefsteak. The fruit averages 8 oz. each on a compact plant. Determinate, 62 days.

Clear Pink Early. 2-3 foot tall plant produces pink tomatoes, about 3-6 oz. Determinate, 58 days.

Grushovka. A pink, egg-shaped, 3-inch long tomato from Siberia. Plants are under three feet tall. Determinate, 65 days.

Manitoba. The fruit is over 6 oz. in size, very productive and early. Determinate, 60 days.

Northern Exposure
. A compact plant that produces 8 oz. "Big Boy" style tomatoes. Determinate, 67 days.

Oregon Spring V.
 Developed at Oregon State University for short season gardens. Medium sized fruit that is nearly seedless. Determinate, 58 days.

Pilgrim VFFA Hybrid
. 8 oz. fruit on a compact plant that boasts excellent yields and good flavor. Determinate, 65 days.

Polar Baby. Developed in Alaska. 2-inch salad tomatoes. Determinate, 60 days.

Prairie Fire. 3-5 oz. tomatoes on short plants. Tangy flavor. Determinate, 55 days.

Red Robin
. The plants get only 12 inches tall, producing cherry-sized tomatoes. Good choice for hanging baskets. Determinate, 63 days.

Siberia. A favorite of Canadian greenhouses, this bushy plant reportedly will set fruit at temperatures as low as 38 degrees. Fruit is under 2 inches in diameter. Determinate, 55 days.

Siletz. 10-12 oz. tomato developed in Oregon. Determinate, 52 days.

Sub Arctic Maxi.
 For very cold climates. 2 oz. fruit on a small plant. Determinate, 62 days.

Sweet Tangerine. Orange-red colored fruit. Determinate, 68 days.

Tumbler. Cherry-sized tomatoes in seven weeks. Good choice for hanging baskets. Determinate, 49 days.

506 Bush. Plants only get 18 inches tall, are drought tolerant and produce medium sized tomatoes. Determinate, 62 days.

 Online sources for these tomato seeds include Tomato Grower's Supply Company and Totally Tomatoes.

Pest Management. In our experience the biggest problem was whitefly infestations. Yellow sticky traps can let you know you have a problem as well as control small outbreaks. Insecticidal soap may be necessary for control of the whitefly problem starts growing. In case of a severe outbreak on a tomato plant, the easiest and most effective course of action? Get rid of the plant.

However...although there are a lot of benefits to growing tomatoes in the fall and winter, there is a lot of time and expense associated with it, especially the heating costs. And, don't expect the sweet, succulent taste of a summer-grown outdoor tomato. But the taste IS better than a store-bought tomato. Just more expensive.