Coppice said:"Potting Soil: is mostly loess. If it has fertility it is chemically added.
It is also a major source of damping off. I don;t use it,
Actually - Loess is a special type of soil and is only found in a very few places in the world. One place is ~ 30 miles NW of me. My Master Naturalist group is called Loess Hills Master Naturalist. Loess would never, ever be found in any type of gardening soil.
I am wondering - did you mean sphagnum peat moss? That is the major constituent in most potting soils, though many higher quality (and priced) mixes are going to coir and eliminating peat.
Higher quality potting soils like Happy Frog and FoxFarm have natural ingredients that provide fertility - they have no "chemicals".
Most quality potting soils are sterilized and do not contribute to damping off. If damping off is causing you problems, start your seeds/water with a solution of Hydrogen Peroxide - 1/2 cup to a gallon of water.
