If you area gets a lot of rainfall, or has soil that drains slowly, you may need to water even less frequently. Soil should dry at least a little between waterings. If soil is visibly wet or damp, you should probably wait to water it.
Heat your soil in the oven for half an hour at 160° F (71° C). Avoid heating your soil using a tarp and solar energy outdoors, which may invite more pests.
Pour ordinary vinegar (or beer) into several jars with lids. Add a few drops of dish soap to the liquid. Close the lids and poke several holes into them. Leave the jars scattered throughout the area infested by gnats. The adults will fly into the jars and die.
Pesticide sprays containing bifenthrin and cyfluthrin can also work. Always follow the instructions and safety recommendations provided with the pesticide spray.
