indoor Fungus :(


Business Member
Got what appears to be white fungus starting to grow on some of the cells.

Current state of the grow area
* temperature steady 70-72F
* humidity 40-45%
* everything on warming mats
* oscillating fan going 24/7 (this cell pack is actually one of the closest, too - doesn't seem to be related)
* watering from below, trying to keep the water level just above the bottom of the cells

Any thoughts?


Extreme Member
IF it's fungal:
Make chamomile tea, dilute it with one gallon of your watering water.. Water with that for a while and it should get rid of any fungal issues you are having. There are other benefits to watering with it, but I only do it in cycles.. Usually with new seed starts. Note that this will also harm other, potentially beneficial fungi you might have present as well.

Could be you are just seeing hard water mineralization?? If you compare with the white you see on the surface in some of my pictures. I don't get it as bad when watering from below, but we do have some hard water here.. Drive nails with the stuff. :P
I use the fishtank as a way to acidify the water more.. It has helped a lot.

Pictures help a lot.
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Business Member
oops, I totally forgot to add the picture!


You can see it in the back. It's only happening on about 4 trays, all the rest are clear. Also of note, the 4 trays with the problem are all these square cells. None of the hex-shaped cells have a problem, but that could easily just be coincidence (not all the square-cell trays have the issue either)
Might be bad, might be benign. You'll know in a day or two if it's a species that causes damping off because it's normally pretty quick. Is this in a commercial greenhouse where you've experienced damping off before? Most of the times I've had damping off issues the fungal mycelium wasn't even visible (yet). The plants look mostly up with cotyledons fully open, so they don't need to be kept constantly so moist on top which will help regardless of what fungus it is. In a few days they'll be past the point where they're vulnerable anyway. I'm thinking if it's so visible at this stage, your plants would have succumbed to damping off already if it were one that causes it.


Extreme Member
Another option along the lines of Crafty's suggestion of chamomile is to put H2O2 in a spray bottle and just lightly spritz the surface of the cells, especially when the surface is a little bit dry. I agree with Northwood that I don't think this is a damping off threat, though I'd be a little concerned about the seeds that have yet to germinate.


Extreme Member
I'd also think it's probably a saphrophytic fungi, that is it just wants to eat the media not the plants. Options to avoid it could be to use a fungicide, or to let the suface of the media dry out.


Business Member
Based on the picture, things look pretty good. Those seedlings look fine.

The soil looks damp for 40-45% humidity. There's a lot of good suggestion here, but all of them could be complemented by running a little drier.
Not sure how to do that without drying out completley. I'm keeping the water level just a little over the bottom of the cells, if I let it get below them they get REALLY dry.

I think at least part of that is the square cells I'm using. The hex ones don't have the same problem. The square ones are different than I'm used to using, I think the holes in the bottom are bigger.
I'm keeping the water level just a little over the bottom of the cells

Bottom watering and sip type systems are a real thing, but allowing seedlings or any age plant in soil to sit in standing water that cannot be absorbed within 30 minutes or so is a whole different story. Seedling type grow mediums in particular soak up water like a sponge, and maintaining that condition 24/7 will deprive the young roots of oxygen and invite mold issues. If it can't go 24 hours after getting soaking wet without completely drying out then I'd be looking at environmental conditions like humidity and temperature, or perhaps the grow medium type and the soil depth of the cells being used. I'd also consider automated watering systems as well if I had dozens of tray tables going, then it wouldn't matter if they had to be watered twice or more per day to keep from totally drying out. Just my 2 cents, so take all this at around that value. 🤑