Maximum Yield Australia/New Zealand March/April 2019 | Page 50

LIGHT LEAKS
AND SEALED GROWROOMS
by Kent Gruetzmacher
Light leaks in your sealed growroom can
be disastrous for some kinds of plants.
They can also be a sign that more than
just light is getting in, including pests
and other environmental variables.
W
hen planning and setting up indoor gardens,
growers spend time and money in the creation
of environments where plant species thrive. For sealed
growrooms, this process represents a careful balancing
act between temperature, humidity, light, and CO 2 .
However, once an indoor grow is operational, these
synthetic environments create challenges for growers
that are non-existent in the natural world. The reaction
of indoor plants to light leaks during dark periods (night-
time) presents one of these unusual phenomena.
Certain species of plants are subject to
photoperiodism, in which the varying duration of
light cycles between day and night cause plants
to enter new phases of growth. To illustrate,
uninterrupted 12-hour periods of darkness (nighttime)
causes some plant species to start flowering. This
process occurs when a hormone called photochrome
reacts to sunlight intensity and durations, directing
plants towards the different phases of growth.
If a sealed growroom is not 100 per cent dark during
the nighttime period, photoperiodism cycles can be
interrupted, causing photochrome imbalances as
related to specific plant processes. These hormonal
imbalances can have negative and sometimes detri-
mental effects on an indoor harvest.
For those looking to avoid issues with light leaks in
their sealed growrooms, consider the following points:
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Maximum Yield
Inconsistencies and Stress
Indoor gardeners should always strive for
consistency in their growroom environments.
Most crops perform best in stable environments,
and bountiful harvests are the result of constant
environmental balance — including stable lighting
intervals — during both vegetative growth and
flowering. A common misconception amongst
indoor growers is that light leaks during the
vegetative growth phase won’t disrupt crop growth.
However, any irregularities in lighting patterns
can stress plants out. Along this line of thought,
all environmental stressors inhibit essential plant
functions, such as nutrient uptake, and retard growth.
Light leaks can also prove troublesome regarding
photochrome levels in plants, as unexpected or
irregular doses of light can alter stable hormonal
conversion processes. During flowering phases,
excess light during dark periods can push
photochrome activity to the point of converting a
plant back into vegetative growth.