Professional Marijuana Grower July-August 2019 Issue | Page 18

that are not flushed. Think of
all the fertilizers, catalysts,
and additives that a cannabis
horticulturist commonly feeds
to his or her plants during a
grow cycle. Most gardeners
understand that these miner-
als can build up in a soil or
medium, but many do not
realize that these minerals
can also build up in the tissue
of the plants. If not removed
properly, these minerals will
remain in the plant tissue and
can affect the flavors, smells,
and medicinal quality of the
harvested cannabis flowers.
A simple, widely used tech-
nique for flushing cannabis
plants prior to harvest is to
stop feeding the plants any
mineral fertilizers during the
last week or two of flowering
and providing the plants with
fresh (pH balanced) water
only. This forces the plant to
use up the minerals remain-
ing in the medium and in the
plant’s reserves (stored miner-
als). By basically starving the
plant, it is forced to use up
the nutrients it has stored in its
tissue. Eliminating the feed-
ing program and switching
to straight water is an effective way to flush cannabis
plants before harvesting. The more stored nutrients the
plant uses up, the less that remain in the tissue. This also
means there is less to affect the quality of the harvested
flowers.
Another option for flushing cannabis plants just prior to
harvesting is to use a specific flushing product. There
are many different types of flushing products available,
each with its own advantages and disadvantages. If
this path is chosen, the grower needs to carefully follow
the manufacturer’s instructions. The difference between
various flushing products is generally how each pro-
motes the flushing process. Some flushing products use
hormones, while others may deliberately cause stress
to the plant’s roots, forcing the plant to use more of the
stored up minerals in its tissue. When to implement a
flushing product will also depend on the product itself.
Some flushing products are designed to be used a week
or two prior to harvest, others are “fed” to the plants up
until the day of harvest. The variation between flushing
products is just one of the reasons why it is so important
18 • Professional Marijuana Grower
for a cannabis cultivator to follow the manufacturer’s
instructions.
Flushing Throughout the Plant’s Life
Cycle
Although flushing at harvest time is crucial for protect-
ing the integrity of a cannabis plant’s odor and flavor
profile, flushing periodically throughout the life cycle
of the cannabis plant may be necessary to maintain
the crop’s optimal health. When minerals build up
in a medium, both the nutrient concentration and the
pH of the nutrient solution can get out of whack. This
can lead to a whole series of problems. The goal of
flushing intermittently throughout the grow cycle is to
restore the balance of the nutrient concentration and pH
in the medium and/or the reservoir. Cannabis plants
rarely absorb nutrients in the exact same ratio as what
has been fed to them. If more nutrients are continually
added, eventually the left over minerals compound and
build up in the medium. Cannabis cultivators who use
chemical fertilizers and never flush their plants could
end up with hindered growth and diminished yields due
to the compounding of nutrients in the medium. Unfor-
July/August 2019