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

Blood meal is a great soil addition but one that needs to be used with care
As far as levels go, even ½ a tablespoon of blood meal in a gallon of soil mix will overdose most
cannabis plants if it is not cooked first. The same approximate measurement applies to guanos, as they
are only slightly more forgiving. I like to use these elements in layers and zones as well as spikes.
Again, it is very important to cook it first in a soil mix when mixed globally, because otherwise it can
really cause big problems with nitrogen overdoses, and actual heat generated by the microlife, not to
mention things like pH fluctuations. You will read in books about blood meal lasting 6 months in a
soil mix, and in a TLO living mix it might last 2 months, but only for 1 month of that will it give
massive nitrogen release, in my experience. Organic matter tends to decompose very quickly in a
TLO environment, and bat and bird guanos only really rock the nitrogen for about 3 weeks and last
about 4 weeks total. There are, of course, plenty of slow-release nutrients that will continue to be
released through the natural cycles of the microbial life, but the “Big Bang” effects of those nutrients
burn out rather quickly.
REV’S TIP
High-phosphorus bird and bat guanos are very acidic and will quickly
lower the pH of your soil mix, so it is not a good idea to mix these
globally. This is due to their highly available levels of phosphorus, which is proven to
discourage fungi and algae in things like golf course ponds and home water features. This
includes the all powerful and beloved Mycorrhizal fungus, so that puts bird and bat guano soil
additions out of favor with TLO growers. You’ll notice the 2.1 soil mix calls for zero highphosphorus
bird or bat guano mixed globally, and there’s a good reason. However, I do love
high-phosphorus guanos in special nutrient blends I use for layers or spikes, for flowering plants.