if you cant get fox farm i went with a straight soil (no time released ferts) and used 50% soil 25% perlite and 25% vermiculite seems to be working okay... soil is staying loose and keeps me from watering but once a week or so.
Miracle Grow and Shultz are both good products. The only problem with them is that they are inconsistent. For example, wood products (ground-up bark and composted sawdust) are a substantial component of each, yet the wood products are not always from the same source--maybe fir from Washington in one batch, pine from Georgia in another. For a production grower or someone counting on a certain result in a certain length of time, having the same soil each time is very important. For a hobbyist, Miracle Grow is fine. It's not really safe to mix your own soil--the components are quite dangerous. Wear a good dust mask, and avoid mixing inside. There are many, many potting soils on the market that will grow outstanding, even truly gourmet, marijuana. Any florist/nursery will have several for sale. For convenience, and the best results, buy one that is relatively light weight. Twenty or thirty years ago, when indoor pot cultivation was in its infancy, the situation was different--mixing your own was practically a necessity. For that reason, there has always been a lingering sense that few, commercial bagged products are good enough for the weed. That is absolutely untrue. Today, you can buy soil for $4 a cubic foot or less that will make for kick-$%& pot!!