I would be interested in the "borax is unhealthy to plants" info.
But barring that, I have a very simple recipe that my wife and I have used for coming up on 10 years.
The current iteration does use a microwave, so I plan on experimenting with other means to get similar results, but I don't think it's possible otherwise:
It is made with a ratio of:
1 bar flaked Ivory Soap: 1 cup borax: 1 cup washing soda
The Ivory soap is flaked in a novel way. You put the soap on a microwave-safe plate and set it to 1 min or so. It's a sight to behold. The soap turns into a massive cloud as the vapor in the soap expands blowing up the pockets. Remove the dish from the microwave - be careful- it will be VERY hot. Pull the fluffy cloud away and take that part and pulverize it in a food processor. There will be a small lump of hot soap left behind and pop that back in the microwave and repeat until the whole thing has been pulverized in this way. Dump the flakes in a canister with the correct ratio of other materials and shake it up.
We usually do 3 bars worth at a time and get enough soap to last about 4 months. I've never done the calculations, but we buy the ingredients in bulk about once a year and it's very reasonable.
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