trends & technology
“
Foliar sprays are
great for tackling
nutrient deficiencies.“
So, let’s have a look at the dos and don’ts of
foliar feeding in the vegetation and flowering
stages of your plant's life.
The Don’ts
DON’T USE A FOLIAR SPRAY
WHEN YOUR LIGHTS ARE ON
If you are growing in an environment with a
powerful artificial light source, the last thing
you want to do is to cover your plant in a liquid
while the light is on. The plant cannot absorb the
freshly sprayed liquid fast enough. The first thing
that’s going to happen is that the liquid will act
as a lens, amplifying the heat from the lights and
burning the leaf. Second, the plant will choke.
Usually, when a plant gets too hot, its stomata
open to release heat, gas, and water to cool down.
However, it will not be able to breathe or self-
regulate if the leaf is covered in a liquid that is
causing its surface to burn.
DON’T USE A FOLIAR SPRAY
IF IT WILL BE DETRIMENTAL TO
YOUR GROWING ENVIRONMENT
Foliar feeding increases the humidity within the
growing environment. This is great while your
plant is in its vegetative stage, but it can be a
problem when your plant is in flower. During
the flowering stage, your humidity is already
high. Environment is such an important factor in
modern hydroponics that I personally wouldn’t
do anything to mess it up.
DON’T USE AN OVERLY
CONCENTRATED FOLIAR SPRAY
When using a foliar spray, make sure you read
the instructions twice and stick to the dilution
rates on the label. In fact, I’d even recommend
over-diluting the foliar spray just to make sure
that you don’t use a mix that could be too strong
for your plant (after all, all plants are different).
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grow cycle
The Dos
DO USE A FOLIAR SPRAY AT LIGHTS OUT
The best time to use a foliar spray is at lights out.
When a plant enters a dark period, its leaves take
around 15 minutes to relax. It’s during this time—
right after the lights turn off and before the leaves
relax—that the stem and leaves are in their most
effective absorption period. Spraying your plant
at this point also means that it has the maximum
amount of time to absorb the nutrients. If you were
to spray your plants too close to lights on, the
plant could still be wet when the lights come on.
This would have the same negative effects on the
plant as if the foliar spray was applied when the
lights were on as discussed previously.
DO USE PROPER TECHNIQUE
WHEN FOLIAR SPRAYING
Cover the plant’s leaves and stem with a light
spray. Remember, less is always more, as your
plants need to absorb all this liquid before the
lights come back on. If the leaves are dripping
wet, you have used too much. It may take you a
few attempts to get it right. A great tip is to use a
foliar sprayer that can be adjusted to expel a fine
mist. Again, the finer the mist, the better it will
be for the plant to absorb. There are also spray
bottles that can be used upside down, which is
great for getting into tight spaces and spraying
the bottom of leaves.
DO USE FOLIAR ABSORPTION
TO YOUR ADVANTAGE
Foliar sprays are great for tackling nutrient
deficiencies. For example, if your plant starts
to show signs of calcium and magnesium defi-
ciency while you are running a nutrient-rich
feeding regime, you could look to use a cal-mag
foliar spray at lights off every five days to rectify
the issue. This way you don’t have to change
your standard feeding regime. This is especially
useful if there are multiple plants in your system
and only a few are showing signs of a deficiency.
The deficient plants can be directly treated with
a foliar spray without jeopardizing the other
plants' feeding schedule.
There is a great range of foliar nutrient feeds
out there. Some reduce internode spacing in the
vegetative stage by creating more branches, some
increase the number of flowering sites while the
plant is in the flower stage, and some help with
the overall health of your plant by combatting
deficiencies, pests, and diseases. The list goes on.
So, the next time you grow, consider using the
secret way in to help take your plants to the
next level.