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

outdoor cannabis. For many years we treated this combo like a big secret because it really made that
much of a difference, so be sure not to leave out the greensand in your grow. Tomatoes, strawberries,
and cannabis all love this amendment. I have noticed greensand tends to buffer pH somewhat as well,
and likely works well with barnyard manures due to this, because manures tend to drop the pH a tad
like most organic matter does while decomposing.
Oyster shell products are uniquely capable of a few excellent contributions to a living soil mix.
Cannabis loves calcium, and microbial life needs and loves calcium as well. Oyster shell products
provide slow-release calcium, and that’s the first benefit, but wait, there’s more—when building soil
mixes you always want to be somewhat aware of the ratio of calcium to magnesium, which should be
around 5:1 respectively. Oyster shell products essentially provide a pure calcium carbonate which
breaks down very slowly, releasing calcium for the microbial life, and hence the plants, to use. If
your magnesium levels get too high, bad things start to happen, and so this can be a tricky dance, due
to the fact that cannabis also loves a lot of magnesium. Dolomite lime (see below) brings in
magnesium along with calcium, and I use this in my mix as well.
I use two grades of oyster shell products, the ground and crushed versions. The crushed is just
larger pieces than the ground, which has a sand-like consistency, and the main difference here is the
length and the strength of the buffering effects the calcium carbonate has on the soil mix. This is
another benefit of using these shells. I like using the ground shells (also known as oyster shell flour)
as a buffer for spike and layer mixes using things like guanos and blood meal in them. If not for the
buffering effects of the ground oyster shell, those products would really take the pH down too low for
a time. In addition, calcium is one of the most underrated nutrients ever in cannabis growing, because
cannabis loves slowly released sources of calcium, and I even use crushed oyster shells in my worm
farm food (kitchen scraps and leftover cannabis matter with shredded junk mail) to make sure my
castings are calcium rich. I advise you to keep calcium on your mind when customizing soil mixes and
you will be one happy camper!
Both crushed (right) and ground (left) oyster shells are fantastic additions to a living soil mix
You can see that I use plenty of the crushed shells globally in the 2.1 soil mix, and this is because I