A gardener writes in:“We used 5 gallon buckets for our 3 tomatoes, 2 squash, and lemon cucumber plants this summer. I seem to have flies in the dirt! Am I over watering? What natural ways can I get rid of them?”
I’m going to take a stab and assume that the flies in question are gnats rather than house flies or white flies. Given that, yes, over watering contributes to this problem. It sounds like you have Fungus Gnats – little flies that lay eggs in the soil where it’s nice and moist, then the eggs develop into larvae and new gnats. These gnats are generally more of a nuisance than dangerous, however they can be a problem if they start feeding off your plants’ roots and stems, which they tend to do in epidemic cases. There are several ways to treat this, and I would suggest a combination of at least two of them to combat your infestation:
1) Let your soil dry out for at least 24 hours. They can’t survive in dry conditions, so you will brake the cycle of life and kill off the larvae. I have to assume that your 5 gallon buckets have good drainage. If not, make sure to prepare your buckets with several drainage holes and some gravel at the bottom next year.
2) Sticky Traps – some people have said that this works, others haven’t had much luck, but it’s worth trying. Place the sticky trap either face down on the soil’s surface or vertically in the stakes that comes with the sticky traps. Change them as often as needed. You can find them either at Gardener’s Supply…
or you can find some more attractive ones at Garden’s Alive.com. Check out these Pot Stickers.
3) You can use a natural larvicide that is added directly to the soil, inoculating it with larvae-eating bacteria called Bacillus thuringiensis (Bti), also from Garden’s Alive. Check out Knock Out Gnats.
4) Put a layer of sand on top of your soil to prevent the adult flies from laying more eggs. It looks attractive and is practically free, depending on how close you live to the beach.
For more info on Fungus Gnats – check out this website:
Thanks for writing in. Keep those questions coming!