Mold or fungus?

Hello all,

My flower seedlings are in trays for starting seeds indoors and some of them have white mold or fungus growing on the dirt. Is that bad for my plants and if so what should I do to get rid of it?

Thank you!

hard to say for sure. many fungi are benign and won't attack the plants and others will cause what is called damping off (the stems will rot near the soil line and then the seedlings will fall over).

if they've had the fungi on there for a while and they've not fallen over yet then it is probably ok to leave alone.

If it is damping off it can kill your plants. That's a big problem when it shows up. The fungus grows because it's damp or wet, especially near the soil line. So how do you fight it?

First you try to prevent it. It's caused by spores so use a sterile potting mix and make sure your seed trays and other stuff are clean when you start the seeds. Wash them every year. You may have done all that and it's too late this time anyway. Spores can float in on the air so no matter how careful you are they can still show up. But "cleanliness" is a decent preventative. You do what you can.

You have a bit of a dilemma. The mold/fungus thrives in wet conditions and you need wet conditions for those seeds to germinate. I put a plastic cover over mine to hold that moisture in. But once enough have germinated I take that cover off and let the surface dry. The sprouts still need moisture so don't let them totally dry out but try to avoid getting the surface wet. The term often used is "water from the bottom". @digits had a good description a few years back about how he manages that. I use a different system but mine are set up for that when the seeds are planted. I'm sure others have their own systems.

Once the sprouts grow enough I often have a small fan blowing on them to help evaporate surface moisture. I think it helps toughen the plants up too. It's not a strong breeze hitting them, fairly gentle. I couldn't find a small fan this time of the year, I had to wait until the heat of summer and remember to get one for the following starting season. Now we have the internet.

If you start different plants in the same planter like I do some will germinate faster than others. It's hard to know when to switch from moist germination mode to growing mode. I don't have a good guideline for that, at some point I just make a decision.

Hopefully it is not damping off. It was not a white mold when I've seen it. The stem of the plant rots off, and is black. But it means that if the right fungi show up it will find good growing conditions.

Good luck!

I'll definitely try the fan. Thank you for all the info!