Over-watering can cause fungus or mold problem on top of the soil as well as poor drainage, pot's too big, and/or poor air circulation.

Either you can re-pot into a faster draining soil and water less letting the soil dry out between watering or, you can try scraping down into the soil a couple inches with a spoon getting out all the gunk you see and discarding, then add new dry soil, water less.

The plant should be somewhat snug in it's pot.

Better air flow around the plant will help the soil dry out faster.

Billy Rae

I had this problem on a hoya a couple months ago. I sprinkled cinnammon onto the soil, and 3 weeks later, it was gone, and has not come back since.

I have a blog post with pics about it, check it out, I hope it helps.

http://damnplants.blogspot.com/2008/01/what-doesnt-kill-it-will-only-make-it.html

Here is a link that might be useful: my blog.....cinnammon on mold

Hi All,

Thanks Billy Rae and Nova for your advice!
There are probably 10 separate plants in this one pot since I combined a number of small pots a few months ago into one large one to save space, so digging out the fungus and adding fresh dirt is virtually impossible. I can find little white dots (spores??) that originate in the mold but fall or penetrate into the dirt up to an inch, and all around the roots. I suppose if it would kill it, I could just bury them with clean dirt... but I've never had this kind of infestation before so I don't know what will work and what will just aggravate the problem.

I tried the cinnamon, (the last of my really good stuff) but it doesn't seem to be doing anything at all. I'm certain that this was brought on by my overwatering so I didn't want to wash the cinnamon through the dirt at the expense of adding more water to the equation.

I did try moving the plant in front of a window that we keep open all the time to ensure that there was good airflow... but it actually spread toward the side with the window.

If I can't figure out anything, I think I might just have to throw the whole thing out to make sure it doesn't spread to my other plants. After all, it is just a spider plant... but it would be terribly missed.

I found a thread at:

http://www.ubcbotanicalgarden.org/forums/showthread.php?t=21429

It sounds similar to your problem.

Lexie,

There is no need to throw out the plants. It shouldn't spread to other plants, although the same thing can happen if they too are over-watered.
Try and let the soil dry out. Fungus, which loves moisture, will have a very hard time surviving in dry soil.

Billy Rae

I will avoid watering until I see the leaves begin to fold over which is their tell-tale sign that they're thirsty. I've moved the plant to a new place where it can get more air flow, but the room is a good bit warmer.
Hopefully it will dehydrate the mold and it will just go away. If not, I'll invest in some houseplant fungicide and some thing very light or non-nutritive (small gravel?) for the soil surface so nothing can stay wet enough to grow.

Thanks everyone for your help!