A good quality potting soil is not really soil at all, but a mix of several ingredients that may include sphagnum peat moss, vermiculite, sand, perlite, or compost.
Make your own potting mixes and seed starting mixes if you need a large amount. It may be easier to just buy a bagged mix if you need a small amount.
Compost and Soil less Mix
2 parts Compost
2 parts Sphagnum Peat Moss
1 part Perlite
1 part Vermiculite
Soilless Potting Mix is a light, weed and disease free combination that is a blend ingredients suitable for starting flowers or vegetable seeds.
Commercial seed starting mixes are predominantly sphagnum peat moss and often contains bark or coconut fiber. Sphagnum peat is lightweight, it will hold moisture but is quick to drain excess water. Peat is also on the acidic side and most seed starting mixes have a soil pH around 5.8, which is good for seed starting.
You do not need to add fertilizer to seed starting mixes. Extra fertilizer may burn new, fragile seedlings. The addition of compost to your mix will provide any extra nutrients that young plants require.
1 part sphagnum peat or coir
1 part peat humus
1 part compost
1 part sharp sand or builder’s sand
Tags: Potting Soil