Custom made soil

Q. In the past I have purchased bags of potting soil, cut out a portion and planted right in the bag in my little greenhouse. However the plants that I have transplanted a week or so ago in the custom made soil are doing really well. I made it with sawdust and washed sand. I would like to replace the bags with custom made soil in pots placed in plastic flats on the benches in the green house but I would like a lighter mix. Can I make it with peat moss or sawdust, perlite and vermiculite? I would also use this for seed starting.

A. We recommend any of several combinations of materials for your potting soil for seedling production. Normally we encourage people to find the items that are available and inexpensive - and in some countries that may include rice hulls and/or ground coconut husks, or even coffee hulls.

In America, sawdust is often the least costly available material, so it is first on our recommended list.

Peat moss and perlite are also excellent materials. Vermiculite is okay, but doesn't last as long as the others. We like sand as a part of the mix, to improve the drainage characteristics of the mix, and normally recommend 25-35% sand, along with any combination of the other materials you prefer.

Perlite and vermiculite can replace the sand if you prefer, but I personally would always include some sand in my mix - even if it is less than 25%.