I recently repotted my aging Christmas cactus using organic Miracle-Gro soil, and now I'm dealing with a swarm of tiny gnat flies! I've already tried setting up sticky yellow pads to catch them. Do you have any suggestions for a spray I could use on the soil? I'm hesitant to repot again with fresh soil since I want to keep this plant healthy.
3 Answers
I've dealt with fungus gnats before and while diatomaceous earth and hydrogen peroxide didn’t work for me, I found success using BTI (often in mosquito bits) along with liquid treatments for the larvae. Plus, yellow sticky traps helped catch the adults to stop them from breeding. It took a month, but now my infestation is mostly gone. Now I even add a bit of BTI when watering my non-succulents as a preventive measure!
Try adding a thin layer of diatomaceous earth over the top of the soil in your pot. It acts like a natural desiccant that dries out and kills the gnats! It's a safe option for your plant.
Miracle-Gro can be prone to bugs right out of the bag. Instead of repotting again, you should treat the soil directly. There are sprays or granules specifically for soil treatment. A good tip is to cover the plant with a bag for about a week after treatment, then remove it. Some people also recommend submerging the soil in water for a few hours, but that might stress your cactus too much. Another option is to bake the soil before use to kill any pests.