A Gardeners Forum Forums Gardening Reference Gardening in 2007 Mold/mildew and gnats in indoor greenhouse?

Several plants that were not doing too well when the forced air gas furnace kicked on are doing a *lot* better in my makeshift greenhouse in the spare bedroom (over-the-commode shelf covered by plastic that covered a new mattress, with a warm mist Vicks vaporizer refilled about every other day).

The gnats are also doing well in there, and any dead spots on the plants are growing white fuzzy mold. I can cut off the dead parts of the plants but the cuts seem to grow the mold as well.

The plants in there now are the corkscrew vine (3 cuttings, 2 finally recuperating), Mexican petunia, and ivy pelargonium. The mold is concentrated on the corkscrew vine.

Any suggestions on how to control the gnats and the mold without killing the plants?

Thanks in advance.

Fungus gnats thrive and produce in moist soil, that kind of moist atmosphere is perfect for mold to grow as well. If your plants can take it without all that constant wet around them, you will probably see a reduction in the gnat population as well as the mold by letting the plants and the soil soil dry out some and get some good air flow around them.

Thank you for the info, DowntoEarth. So I can make this good news either way:

Right now, the last corkscrew vine cutting is beginning to fail from presumed root rot (I haven't watered it for around two months but I guess the humidity level it wanted for the stem/leaf to stay green was high enough to keep the soil from ever drying out also and so the roots rotted).

So, if it lives, it'll be a miracle and I'll have a corkscrew vine in my yard this summer.


I just keep learning and learning... next time will turn out better!

Have you tried putting one of those little fans in the area?? It would help circulate the air..

the fan is a good idea to get the airflow going.

with the mold issues, it sounds like it's too high on the humidity level. i'd cut back on the vaporizor a bit. instead of letting it run all the time, just put it on for an hour or so at a time, a few times a day. you've got the plants covered with the plastic, so that will retain the moist air.

i hope you manage to save the corkscrew vine!!!

If you really want to control the fungus gnats use beneficial nematodes. They will kill them, not just reduce what you are seeing like reducing watering. Also FYI fungus gnats vector plant pathogens, so if you are having any kind of disease issue you need to control you fungus gnats to stop them from spreading plant diseases.

Fungus Gnats

Beneficial Nematodes