True Living Organics - The Ultimate Guide to Growing All-Natural Marijuana Indoors (2012)

This powdered rock phosphate is a little lower in phosphorus
Gypsum is one of the most underappreciated elements in many all-natural gardens, and what it brings
to the table is all good for cannabis especially. Some ancient organic growers from around “The
Pygmy Forest” in Northern California used to rave all the time about gypsum, and how the slowrelease
sulfur enhanced natural smells and flavors in the final cannabis buds. Gypsum is calcium and
sulfur, and many people believe, as I used to, that it radically lowers soil pH. The truth is that it will
have this effect in soils that are already very low, and I think this is due to the fact that fungi really
love gypsum. Outdoors gypsum works wonders on big clay-packed soils, and aerates them by
somehow bringing in fungus to thrive on the clay minerals. Where fungi are dominant they tend to
cause the pH to drop, as most of them prefer a lower soil pH. The upshot of this is that you should not
make the mistake of using gypsum in a soil mix that has a low pH to start with: the low pH will give
the fungi a little too much help and an unfair advantage. If the fungi get out of hand they will normally
take the pH way too low and fry the plants. They seem to have done that to me in the past on three or
four occasions.
I use powdered gypsum and love it for its slow-release sulfur