We are in desperate need of advice! It appears that we have an infestation of fungus gnats in all nine of our houseplants. Five of the plants are in one room where it seems to be most prevalent. Can you recommend anything to get rid of them? We've tried "bombing" the room with Raid House & Garden, which says it won't harm plants. We are also spraying the plants and the top of the soil directly with "Safer" brand Houseplant Insect Killing Soap. Lastly, we are watering the plants with a solution of 1 gallon of water with 2 tsp. of liquid dishwashing soap. At this writing, nothing seems to be working. Anything you might suggest? -- Frank and Susan Galan
Fungus gnats are living in the soil, not on the plants, so the best thing to do would be to repot all your plants. Bring them outside and remove them from their pots. Discard the soil and wash pots with a 10 percent bleach solution. Rinse well. Then rinse the plants -- foliage and roots -- with a very gentle stream of water and replant in new sterile potting mix. To kill any flying adults in the house, use a product containing pyrethrum or tetrmethrum, or use fly paper.
Update: The Galans responded this morning:
Just to let you know, we repotted all the plants last weekend in fresh soil and new pots, washed the roots and foliage, and it seems (so far) to have done the trick!! Haven't seen one bug flying or on the fly paper since. Your advice was extremely helpful.
Thanks sooooo much!!!!!