Watering is a critical part of plant care, and bottom watering can help prevent yucky things like fungus gnats.
To avoid attracting any nasty gnats in the first place, it's best to bottom water your plants. Get a large flat tray, container, bathtub or sink with an inch of filtered or rain water. Place your plants into the water in only their nursery pots. Leave your plants for 15-20 minutes to soak up any water they might need.
'You may want to cover the top of your soil with fine sand or small stones to prevent gnats from laying their eggs,' Rachel continues. This can be an effective deterrent when paired with other prevention methods. Using cinnamon in your soil is also a creative way of preventing fungus gnat infestations.
Make the natural habitat inhospitable. This means drying out the soil they live in because fungus gnat larvae need moist soil. If you let it dry out completely before your next watering, it will get rid of the gnats in the soil and discourage new adults from laying their eggs.
Another advantage of bottom-watering your plant is that the top of the soil never gets moist. This dry layer of soil on top helps you to keep insects, fungi, and other pests away from your plant. These pests are all attracted to moisture and thrive in an environment that's humid.
Can you over water by bottom watering? Yes, if the plant is sitting in water too long, you can still overwater your plant through bottom watering. However, bottom watering is a more controlled method of watering your plants.
Keep soil dry: Fungus gnats seek out moist soil, so allowing your houseplants to dry out a bit between waterings can slow down or stop an infestation. Let the top inch or two of soil dry out before watering again, and try to go as long as possible between waterings.
Do gnats go away on their own? No, it's unlikely that gnats will go away on their own once they start reproducing. You will need to take proper measures to get rid of them, such as putting away your fruits, flushing out your drains, or changing the soil in your indoor plants' pots.
Drench the soil with microbial insecticide, such as bacillus thuringiensis, more commonly called Bt. This is the most effective way to kill any fungus gnat larvae. Allow the soil to dry out for a few days, so that the top 2 inches (5 centimeters) are really dry. The larvae of fungus gnats cannot survive in dry soil.
“These pests are attracted to moisture, so you may see swarms in areas with damp soils, standing water, or even houseplants that have been overwatered,” Ludwiczak adds. “The breeding habits of gnats are most active during warmer months, which is why they seem to be especially prevalent during summer.”
Steinernema feltiae Nematodes
Steinernema feltiae is primarily used against fungus gnat larvae and western flower thrips pupae in the soil. Fungus gnat larvae may be parasitized in any larval stage.
All you need to do is set the potted plant (be sure it has drainage holes) into the bathtub, sink, or another container that's filled with a couple inches of water. After 15 to 20 minutes, the plant will have absorbed the exact amount it needs—never too little or too much.
How Often to Bottom Water Plants. You should bottom water your plant when your plant needs to be watered. Obviously, this varies wildly from plant to plant and can also depend on the time of year, your plant's light conditions, and environmental humidity levels.
Because fungus gnats thrive in moist conditions, especially where there is an abundance of decaying vegetation and fungi, avoid overwatering and provide good drainage. Allow the surface of container soil to dry between waterings. Clean up standing water, and eliminate any plumbing or irrigation system leaks.
Step 1:Make the sand trap Collect all infected houseplants, and remove the top 2 inches of potting mix to dispose of the larvae already laid. Discard the soil immediately, and replace this top layer with sand, which is free of organic matter and dries out quickly—an unappealing medium for fungus-gnat eggs.
If you've got fungus gnats, you most likely also have pythium root rot, as gnats can carry it. Yay, fungus gnats and root destroying bacteria! Phytophthora and Fusarium are fungi found naturally in the soil; there are several different species.
Hydrogen peroxide will kill the gnat larvae and not injure your plant. Keep reapplying weekly until you notice the gnats are gone.
Unlike hydrogen peroxide, neem oil solutions kill both larvae and fungus gnats and thereby speed up the process of eliminating the pests for good. To create a neem oil spray, simply mix a teaspoon of dish detergent with a gallon of water and two tablespoons of neem oil.
Cinnamon is a powerful natural fungicide, which kills off the gnats' primary food source, therefore making the soil inhospitable. You can also use a cinnamon stick, just pop it straight into the soil. You can grab either cinnamon sticks or powder next time you're doing your supermarket shop.
Consistent watering – Bottom watering provides an even distribution of moisture throughout the entire mass of soil. Top watering can result in dry spots, but this isn't an issue when water is slowly absorbed from the bottom. You can be assured your plants are getting enough water.
Dry Out the Soil: If the fungus gnat infestation isn't too severe, you can just allow your plant to dry out, which will get rid of the fungus. No fungus means no fungus gnats! Don't worry; your plant will recover quickly from a brief underwatering.