Maximum Yield Cannabis USA March/April 2019 | Page 24

pH and Nutrient Availability
As important as nutrients, if not more so, is the pH of the soil
or media the cannabis is growing in. The pH is a measure
of the acidity or alkalinity of soil or growing medium. Soils
or other media with a pH of less than 7.0 are acidic; soils
or other media with a pH greater than 7.0 are alkaline. The
pH scale is exponential, with each number representing a
factor of 10 times greater or less than the number next to
it. For example, a pH of 6.0 is 10 times more acidic than a
pH of 7.0, and 100 times more acidic than a pH of 8.0. What
does this have to do with the essential nutrients needed for
growing cannabis? Nutrients may well be present in suffi-
cient amounts to support robust growth and plant function,
but they can be locked out or otherwise made unavailable to
the plant. The ideal pH range to try to maintain for cannabis
is generally accepted to be in the 6.0 to 6.5 range, with some
variation depending on media selected. To determine pH,
make sure to perform a soil analysis.
Soil testing can be a simple do-it-yourself procedure or can be
done by a reputable lab. It’s a routine procedure and is rela-
tively inexpensive either way. A DIY kit may cost only a few
dollars and give you instant results, but most kits will not
offer the kind of precise results a lab analysis can yield. In
most scenarios, a small amount of soil or growing media can
be sent into a private or university-owned lab and within a
few days to a week or so, a detailed report will reveal many
important aspects of your media. Some labs offer a number
of services where they can give you current nutrient levels,
percentage of organic matter, and other relevant information
so that you can make the necessary adjustments to ensure
your cannabis has what it needs to thrive.
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Maximum Yield