There is nothing magical about "Mel's Mix." I used it, but don't think it is absolutely necessary. Regular soil with a lot of compost mixed in would work well also.

I agree with danny. Mel's mix is all store bought unless you have enough compost on hand. For a single 4x4 frame it isn't too bad, but start expanding and it costs quite a bit.

While Sq Ft. Gardening is a popular concept these days, it really isn't 'new'. It is simply the 'latest and greatest' revitalization of intensive cropping. The raised bed, close spacing, etc. are not unique to Sq. Ft. Gardening.

Most raised bed, intensive cropping methods call only for good garden soil well amended with organic matter. They key here is 'good' garden soil. That means a loamy type soil, not pure clay or sand.

I think maybe Mel came up with his mix to avoid all the variables that would be involved if people were using their 'yard dirt'. That's just pure speculation on my part though.

Well, I agree with Username_5's assessment: in "Square Foot Gardening" Mel standardized well-established intensive gardening methods in a way that is easy to replicate, even with no prior practical gardening experience. His innovation was working out a way to present intensive gardening methods in a cookie-cutter simple approach. In particular, the planting grids and spacing guides he assembled filled in a gap on how to plant intensively and "Mel's Mix" gives a good indication of what soil should ideally resemble.

Depends on where you are and how good your topsoil is. In South Carolina my beds eat organic matter and I am constantly adding to the beds -- it disappears. When I gardened in Ohio we had such rich garden soil I didn't add much just a little compost.

Mel's Mix gives consistant results but is not always necessary for good results.