Fungus gnats are a common problem with indoor houseplants. Gross! Here is an easy solution.
Its the end of February and if you are like me, you've managed to keep your indoor houseplants relatively healthy through the worst of the winter. Then suddenly you notice those pesky fungus gnats flying around your favorite Begonia. What to do?
After exploring many methods I've finally found a solution that will cure this common problem! The first step is to get the adult pest populations under control. Begin by using a fly trap on all of your windows. I recommend the brand below. These traps come in clear sheets that have a sticky solution that attracts the gnats. Simply peel the self stick tape off the back and place them on your window. The gnats are attracted to light and heat. You'll notice the majority of them will gravitate to the windows with the most sunlight.
Now to target the affected plants. I do the shake test. If fungus gnats are present they will immediately fly off of the plant when you shake the pot.
Once you have determined which plants have the issue allow the soil to dry out. A blow dryer on the warm setting can help speed up the process.
Take a spoon and skim off the top 1" inch of soil. This is where they lay their eggs!
Next apply a granular product around the rim of the pot designed to sterilize the soil. This eliminates the ability for them to reproduce.
Mosquito Bits is a readily available product that works very well in treating the problem.
Finally add 1" of fresh potting mix around the base of the plant and gently incorporate the granules into the top layer of the soil with a spoon. Water the plants deeply and let them drain in the sink before putting them back in their original locations.
Within one week your problem is solved! I recommend repeating this process 2-3 times during the winter months when these gnats are at their worst. Adding a small fan to keep the air circulating is an added measure to help protect your plants from these and other common pests.