Question
Thank you for your quick and knowedgeable response.  I do have two follow up questions.  1. you mentioned chemical fungicides as a possibity; I would use it as a last resort, but would like to know what is effective and would not damage the plants.
2.  I have family members in my home with ashma/allergies and I guess that is why the mold bothers my conscience.  I do not repot the plants when any of the family around so as not to put more mold spores into the air.  But I am concerned that the visible mold on the soil is still a health hazard. Do you have any experience with this issue.  Thank you so much.
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Followup To

Question -
I have many houseplants and have for most of my life.  Lately I have a new problem...the soil has white mold in and on top of it.  I do NOT water them too much, I let them get bone dry (for several days at a time) before watering them again.  I buy well known brands of potting soil.

I do not want to destroy the plants and start over.  I have tried repotting after getting all the soil possible off the roots.  I have not done that with all of them because I have a lot of plants and that is hard on them.  Is the mold also in the air?  Is that causing it to recur in the soil?  I don't use a humidifier at home. Thank you for your help.

My other question is about my jade plants.  A few leaves at a time get round black depressed areas either on the edge or in the middle of the "leaves".  These will die and drop off.  I have never had this problem in the past with jades.  I don't overwater them...they stay dry for quite a few days between waterings.  Thank you.

Answer -
Hi Kathy,

Mold is a fungus. It grows when there are spores present in the soil. The spores can drift through the air, but more often they are in the packaged soil - even name-brand soils. Although it is no guarantee, using soilless, peat-based potting mixes will improve your chances of getting sterile soil. It sounds like the mold spores have spread from one plant to another in your collection.

Mold is not harmful to plants, so there is no reason to panic. It doesn't look great, so you probably want to eradicate it. Usually, if you are persistent in scraping off any mold and the surrounding soil and discarding it, then eventually you will have success in eradicating it. But it does take persistence and patience. they are also chemical fungicides available to treat the mold.

Repotting is not a good idea as that can cause other problems and may not eliminate the mold anyway.

Allowing your plants to stay as dry as possible will also help deter the mold. I know you said that you are letting your plants get dry. Perhaps they can get even drier before they wilt. Bone dry on the soil surface may not be dry enough deeper in the soil. Push the envelope here as much as possible.

Sometimes Jades develop a few deformed leaves for no discernible reason. This can be ignored. If the leaf deformity is extensive, then that is almost always due to overwatering. Let your jade dry to the point where the leaves start to shrivel just a bit, then water thoroughly. You may be surprised how long a Jade can go between waterings, especially if it is in a large pot.

Please let me know if any of this is unclear or if you have any additional questions.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: [email protected]

Visit my web site at www.HorticulturalHelp.com

If you would like to e-mail me some photos, I may be able to provide some additional insights.  

Answer
Hi Kathy,

I am not in a position to recommend specific fungicides. I suggest that yo go to your local plant supplier or garden center and see what they have available. Read the labels carefully and look for something that has systemic properties, can be applied as a soil drench, is safe to use indoors, and includes many of your plants in the "safe to use on" list.

Your question about the possible health hazards of common soil molds would have to be answered by an allergist. That really is a question outside my area of expertise.

Regards,
Will Creed