This post is only for those of you who garden somewhat seriously. It's getting harder and harder to find good potting soil. In their efforts to make it cheaply the major providers like Miracle-Gro and Scott's (actually the same company) are using more and more cheap organic products like finely ground pine bark to stretch their product. While pine bark is not, in itself, that bad and actually does help loosen soil it isn't the best of growing mediums all by itself. A lot of these "potting soils" are also enriched with chemical fertilizers which makes them a no no for us organic types.
The best and most economical alternative is to make your own potting soil and it is ridiculously easy. Here is the formula I use and it seems to work for me as a potting medium and a seed starting medium.
1 part sphagnum peat moss
1 part vermiculite or perlite(I use vermiculite)
1/4 part earth worm castings
All of these ingredients are usually available at a good garden center though don't look for them at places such as Home Depot or Lowe's. I mean a real garden center.
You can usually find the peat moss in bales and the easiest size to work with for me is 2.2 cubic foot one. Vermiculite normally comes in 2 or 4 cubic foot bags and the earth worm castings come in 1 cubic foot bags. This is convenient since you can mix one bale of peat with one bag(2 cu.ft.) of vermiculite and a bag of earthworm castings and you have a great potting mix that will turn out cheaper than buying the already mixed stuff. If you want to extend your mix you can add a couple of 1.5 cubic bags of organic potting soil(which is going to be about 50-60% pine bark). That's your choice. Another benefit of making your own is it can almost be considered sterile and there is much less chance of disease or weed seed in it than with commercial stuff.
I mention all this because I spent the afternoon yesterday fixing my laziness. I was in a hurry and pressed for time and I wanted to get my greenhouse boxes planted a couple of weeks ago for my winter salad stuff. I cheated and used organic potting mix from Home Depot (Scott's). I got some germination but everything just stalled and then croaked. I spent the afternoon yesterday making a batch of my own potting soil and dumping the store bought stuff and replanting all the greenhouse beds....that'll teach me.
