Home Remedies for Fungus Gnat and
by Arzeena Hamir
Late winter and early spring is a great
time to start seedlings and get the gardening season
underway. Growing your own seedlings from seed is highly
rewarding and can open doors to even more species that
are not often found in garden centers. However, a couple
of problems can sometimes curb the indoor green thumb
and seriously affect the success of growing seedlings.
Fungus gnats and damping-off are two afflictions that
commonly affect gardeners. However, before you spend
money on expensive chemicals, the solution to these
problems may actually be much more low cost that you
These tiny, black insects seem innocuous
enough as they buzz over your plants. While the adults
rarely cause any problems to plants, if the young larvae
are in large numbers, they can damage your seedlings.
Fungus gnats search out moist soil in which to lay their
eggs. When the eggs hatch, the larvae will feed on the
roots of your plants. Healthy seedlings will often be
able to withstand this feeding but any seedlings that
have small root systems like onions and leeks and those
that are showing symptoms of nutrient stress can be
put back quite significantly.
The easiest way to prevent fungus gnats
is to water your plants properly. Overwatering, which
causes your potting mix to remain moist for extended
periods of time, seems to attract fungus gnats. If your
plants are already infected, allow the soil to dry out
between watering. Alternatively, sprinkle a ¼”
of sand on top of your soil to confuse the adults. Since
the sand drains water quickly, it can sometimes trick
the adults into thinking the soil is dry.
Potting mixes containing peat seem to
be particularly affected by fungus gnats. If the problem
is reoccurring for you, think about switching from a
peat-based mix to one that only contains perlite and
vermiculite. Lastly, if the adult fungus gnats are bothersome,
trap them by making your own sticky trap. The adults
are attracted to the color yellow. Make your own sticky
trap by smearing Vaseline or Tanglefoot on a yellow
surface and hang it up close to where the adults congregate.
Not only will controlling your watering
help to prevent fungus gnats, it will prevent the second
most common problem, damping-off. This condition is
caused by several fungi such as Phtophtora and Pythium.
These fungi live at the soil line, just where air meets
the moist soil surface. When your potting soil is kept
continuously moist by overwatering, the fungi attack
your seedlings. The telltale symptom is a constricted
stem, just at or below the soil surface. Once seedlings
are infected, they tend to fall over at the soil line.
As mentioned, allowing the soil surface
to dry out will go a long way in preventing this problem.
If, for some reason, your potting mix remains wet for
an extended period of time, look to your kitchen cabinet
to help prevent the disease. Cinnamon powder is a natural
fungicide and has been shown to be particularly effective
against damping-off. In addition, Weak chamomile tea
(after it has cooled) is another natural fungicide.
Ensuring seedling success need not be
complicated or expensive. Controlling your watering
and a few home made remedies will go a long way to guaranteeing
Arzeena is an agronomist and gardenwriter
for Organic Living Newsletter. Subscribe to this free
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