How to make your own potting mix
-- Jessica Damiano
VIDEO: How to repot a plant
Whether you're starting seeds indoors or filling pots for planting annuals, soilless potting mix is the way to go. Garden soil shouldn't be used for several reasons. First, it's too heavy, making it difficult and impractical to move large planters around. Second, soil can harbor pests and diseases that can interfere with the healthy growth of plants. Third, it doesn't drain as easily and can become compacted, hindering the germination of seeds and the growth of young roots. Soilless mixes are sterile and have a light texture that allows for easier germination, root growth and transplanting. Just be sure to purchase only horticultural-grade ingredients.
To make one bushel: 1) Pour four gallons sphagnum peat moss into a tub or bucket.
2) Add one pint of water and mix well.
Peat holds water admirably while providing for good aeration, but stick to recommended proportions; too much will hinder drainage and contribute to root rot.
3) Add four gallons perlite or vermiculite (No. 2 or 3 size). Perlite is made from volcanic rock and aids drainage. Avoid breathing in its dust when you open the bag. Vermiculite comes from clay in the mica family. Like perlite, the gray flakes retain air but also hold moisture and nutrients.
4) Add nutrients suited for what you'll be growing. (This initial fertilizer will be used up in three weeks. Replenish it every two weeks with a water-soluble fertilizer at the rate recommended on the package.)
For window boxes and planters: 1 tablespoon calcium or potassium nitrate 2 tablespoons 20 percent superphosphate 4 tablespoons dolomitic limestone 1/2 tablespoon 10 percent chelated iron
For houseplants: 2 tablespoons agricultural limestone 2 tablespoons 20 percent superphosphate 2 tablespoons potassium nitrate or calcium nitrate
For starting seeds indoors: No fertilizer is needed because by the time seedlings grow true leaves and actually need nutrients, the fertilizer will have dissipated. Instead, incorporate a 5-10-5 or 10-10-10 product into the planting bed at the rate of 3 pounds per 100 square feet before transplanting.