I would hazard a guess and say that you can go ahead and use it. Check for additives, but this stuff is meant to be used around reptiles which do not tolerate much in the way of chemical toxins. If tropical snakes can live in this stuff with no ill effects, I would consider it completely safe. People who keep snakes, which I used to, are very careful what they expose their animals to. As far how it will work in your garden, at half-price I'd give it a shot and see how it goes.