grow lights on trial
reduce the harvest on the other side
by overfeeding. Conversely, if your mix
caters to the light feeders, the hungry
ones won’t perform as well. One option
for resolving differences in nutritional
requirements between the two sides
is to mix the nutrient solution for the
weak feeders, then supplement nutrition for the stronger eaters through
foliar feeding, but this method invalidates the reason for having a single
reservoir in the first place.
Location
The specific varieties
of plants selected for
grow light trials can
influence the outcome.
A proper trial would
include multiple plants and different
genotypes within a plant family.
Nutrients
The next factor in setting up a trial is
deciding whether the plants are going
to be fed the same nutritional program,
or whether custom blends will be used
for each side. Most people I talk to
want to see a single tank for both sides.
This too has its problems. Depending
on the plants and their environmental
conditions, the plants under one of the
lights might want a different nutrient strength. This could be driven by
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higher leaf temperature, particularly
on the HID side, which increases the
transpiration rate of the plants and
therefore their uptake of nutrients
from the feed solution. Differences
between how the plants absorb light
from the two different light sources
can also drive differences in how they
uptake and absorb nutrients.
So, which side do you mix the nutrient
tank to feed? If you feed to the side that
needs a heavier nutrient solution, you’ll
The location of a trial might also
influence its outcome. For example, in
Alaska, I believe most indoor gardeners would choose to use HID lighting
because the general climate is cold (in
regards to plants—no offence to readers)! Gardeners in Alaska can use the
extra heat produced by HID lamps to
maintain optimal garden temperatures
and even pump some of that heat into
their living space. Growers using LED
grow lights in Alaska will most likely
require a heater in their garden to
maintain appropriate temperatures.
This could negate the energy savings
of LED grow lights and make them
more expensive to operate than HIDs.
Meanwhile, gardening in Florida with
LED grow lights makes great sense.
Florida is hot, and growrooms in this
region do not need any extra heat
dumped into the garden from HIDs.
Additionally, electricity is expensive in
Florida, and less heat means less need
for a huge air-conditioning unit, which
helps save on energy bills.
Seasonality
Seasonality may also affect which type
of grow lights perform better during
a side-by-side trial. Some climates shift
dramatically from summer to winter in
both temperature and humidity levels.
It’s ideal to conduct multiple trials in
both summer and winter. Although
it’s an expensive solution, research
could determine LEDs are better in the
summer, and HIDs are better in the
winter. Or not.