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  #1  
Old September 28th, 2006, 07:12 PM
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MDNemec MDNemec is offline
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Is mold on the top layer of houseplant soil harmful?

I specifically chose low-light houseplants for my low-light apartment. Most of them also like to stay well watered (like my peace-lily). Although they seem to be happy and healthy, I have noticed the growth of a white fuzzy mold on the surface of their soil.

Is this unhealthy for my plants?

If so, any suggestions on what I can use to treat this mold seeing as how the light/watering conditions of the plants aren't likely to change?


*If I have posted this in the wrong forum, please move it wherever it is most fit (I wasn't sure if this was a soil or pest management question)!
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  #2  
Old September 28th, 2006, 08:19 PM
Newt Newt is offline
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Re: Is mold on the top layer of houseplant soil harmful?

Hi MDNemec,

Since you have low light plants you probably need to cut back on your watering. It's unfortunate you say your watering techniques aren't likely to change as that is what needs to happen. Peace lilies prefer the soil to dry slightly before watering.

I would suggest you scrape off the moldy soil and add some fresh potting soil to replace. Water your peace lily when the top inch or two of soil is dry. You can put your finger in up to the first or second knuckle to see if it's still moist. Don't let water sit in the saucer for more then 15 minutes or so.

You can check the water and light requirements of many of your plants here.
http://aggie-horticulture.tamu.edu/i...e/index.html#D

Newt
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  #3  
Old September 28th, 2006, 09:00 PM
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MDNemec MDNemec is offline
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Re: Is mold on the top layer of houseplant soil harmful?

I think your suggestions are excellent Newt, and I will try to water a little less. (I currently water only once a week. Usually, if I wait longer, my peace-lily begins to droop, but I will try to go a few more days in between!). Additionally, I will try scraping off the moldy soil and replacing it!

My initial concern was that mold on the soil (even though it is not on the plant itself) might be unhealthy for my plants. Unfortunately, although I am a microbiologist, my expertise is in bacteriology and not mycology. Still, I do know how nasty certain fungi can be to both humans and plants and just wanted to make sure my plants didn't need any special anti-fungal agent applied to their soil!

Thanks again, especially for the link, I received my bachelors degree from TAMU!
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Old September 30th, 2006, 09:46 AM
Newt Newt is offline
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Re: Is mold on the top layer of houseplant soil harmful?

How interesting about your profession! I'm thinking that your peace lily may be rootbound and need a repotting if it wilts in a week. Consider gently removing it from the pot to take a look. If it needs a new pot go 2" larger and tease the roots if they are winding around inside the pot.
http://hort.ifas.ufl.edu/woody/planting/manyroots.htm
http://www.dirtdoctor.com/view_question.php?id=70
http://www.ourgardengang.com/containerpotting.htm

If the fungus reappears you could make a solution of vinegar as a fungal treatment and spray it on top of the soil before you water a couple of times. Here's some home made remedies for fungal problems you should find helpful.
http://www.ghorganics.com/page15.html

Newt
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  #5  
Old January 12th, 2008, 11:08 AM
eve eve is offline
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Re: Is mold on the top layer of houseplant soil harmful?

not for the plant , but to people.
I scratched the mold off, and instantly had a sneezing spell.
As I noticed this sneezing spells before, going into the room, is the vinegar all one has to ?
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  #6  
Old January 13th, 2008, 06:55 AM
katsen katsen is offline
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Re: Is mold on the top layer of houseplant soil harmful?

my plants have this also! interested in the outcome of the question. Anne
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  #7  
Old January 19th, 2008, 08:45 AM
Anne Taylor Anne Taylor is offline
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Re: Is mold on the top layer of houseplant soil harmful?

Try sprinkling the top of the soil with cinnamon. Although with the vinegar it could start to smell like an exotic dish..... Cinnamon is a natural funicide. Any time you shift the light/water/Ph or other factor it will disrupt the growth pattern of the 'bugs'. So you should be able to get a handle on it.
Anne
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Old January 19th, 2008, 01:35 PM
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Bluewing Bluewing is offline
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Re: Is mold on the top layer of houseplant soil harmful?

I always water my peace lily once a week and I've never had any mold problems so far. So if your getting mold on moisture loving plants, maybe the pots too big, thus holding more wet soil than need be? watering when you the soil is moist enough and needs a few more days, or, maybe the soil isn't light and airy enough to let more air in?

Last edited by Bluewing; January 19th, 2008 at 08:23 PM.
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  #9  
Old November 14th, 2010, 10:54 AM
Ginger Spot Ginger Spot is offline
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Re: Is mold on the top layer of houseplant soil harmful?

Quote:
Originally Posted by Anne Taylor View Post
Try sprinkling the top of the soil with cinnamon. Although with the vinegar it could start to smell like an exotic dish..... Cinnamon is a natural funicide. Any time you shift the light/water/Ph or other factor it will disrupt the growth pattern of the 'bugs'. So you should be able to get a handle on it.
Anne
Thanks for your cinnamon suggestion, Anne. I also have some white mold growing on top of the soil on a couple of my houseplants. I'll definitely cut down on the watering and I have just sprinkled some cinnamon on the soil. I'm looking forward to see the results.
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Old November 26th, 2010, 01:55 PM
Talouly Talouly is offline
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Re: Is mold on the top layer of houseplant soil harmful?

I too have a layer of white fuzz growing on many of my houseplants. Last week when I first noticed this problem I took my shop vac and sucked up the top layer of soil, removing all visible white mold. I then added a little more fresh potting soil on top. With in several days the white fuzz is back! Will the cinnamon take of this problem?
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  #11  
Old January 6th, 2011, 11:20 PM
mloma mloma is offline
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Re: Is mold on the top layer of houseplant soil harmful?

I too have found this white mold on the top layer of soil in my house plants, but only in the last 2-3 weeks. In addition, I have noticed that the humidity has increased in my whole flat.
In my living room alone I have 27 plants ranging from 1 meter to 3 meters. Through out the 110 sq meter flat I have about 50 plants mostly 2-3 meters tall. My husband says I have too many plants in the room and creating too much carbon dioxides?

The humidity here in Basel is quite high, and was wondering if this promotes the growth of this particular mold as I only water every 10 days? I would add that my gorgeous Ficus, umbrella, and Yucca palm trees which are normally so hearty are not looking so swell.

So if I understand correctly - I should choose to either use the vinegar solution or sprinkle cinnamon. One or the other, but not both - correct?

Thanks for your help,
Maya
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  #12  
Old January 7th, 2011, 07:55 PM
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Tony O Tony O is offline
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Re: Is mold on the top layer of houseplant soil harmful?

Quote:
Originally Posted by mloma View Post
My husband says I have too many plants in the room and creating too much carbon dioxides?
Tell your husband the plants are adding a lot more of the much needed oxygen to your rooms.
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  #13  
Old June 19th, 2011, 08:44 AM
Ellisbrayham@shaw.ca Ellisbrayham@shaw.ca is offline
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Re: Is mold on the top layer of houseplant soil harmful?

Just a thought, but we had a similar problem with outdoor soil, and were told its because of soil had a mushroom compost content, hence the spores. So far they appear to be harmless.
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Old June 20th, 2011, 01:53 PM
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Fen Sandar Fen Sandar is offline
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Re: Is mold on the top layer of houseplant soil harmful?

Fungus gnats can also cause issues with mold. They invade every year here and make nuisances of themselves.

The cinnamon works provided the soil is not sopping wet. But if you have senile and very old cats like mine, it makes them curious about everything which they must then try to eat. (If they weren't already doing so - I caught one of mine this morning chomping off more leaves.)

Vinegar can be risky if you have touchy plants. I lost a few while trying this because I could not get the portions of vinegar to water right at the time. It is more risky if you have a problem with soil that compacts and does not drain properly.

Hydrogen peroxide diluted by water seems to work fairly well. I have been using a shot glass of peroxide in my 2L watering can when I water since January. It kills the soft bodied fungus gnat larvae on the day that you water which cuts back on molding issues caused by the gnats. You will still have them but if you are able to time your watering well or get really lucky, you may be able to kill off the batch of larvae as the airborne gnats are starting to die off. It also adds to the soil air content, but will kill all of your helpful fungi along with the ones you don't want. It also doesn't smell as bad as some of the fungicides you can buy and is infinitely cheaper.

Cape sundews will eat adult gnats at a fairly respectable rate provided they are kept healthy through warmth, proper poting media (peat moss - no nutrients because nutrients in the soil will kill these), direct sunlight and distilled or rain water.

But what it comes down to is that if your soil doesn't drain properly, you need to find a way to make it do so. Soggy roots don't receive enough oxygen which causes them to rot and the soil around them to mold. With summer here, mold spores are everywhere and causing problems to the many people who have mold allergies.
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Old May 15th, 2012, 10:00 AM
newbie12345 newbie12345 is offline
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Re: Is mold on the top layer of houseplant soil harmful?

I am facing the same situation, mold layer on top. I see this problem is very common. But will add 2 things here which make me think the problem is more than mere overwatering and/or lack of sun.

first, my leftover potting soil put in a vaccum sealed pack, purchased form walmart, also grew same molds. Couldn't just be watering issue. Second, the molds killed a perfectly healthy basil plant since I could not get to it for few days. Leaves and young stems literally fell off in the pot while still green.

I know new to this, so don't really know whats going on. comments welcome
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  #16  
Old May 17th, 2012, 05:33 PM
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Fen Sandar Fen Sandar is offline
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Re: Is mold on the top layer of houseplant soil harmful?

If the soil is suspect, get your plants out of if immediately and go bake your soil in the oven at about the boiling point of water (I think anywhere from 180-200 will be fine for U.S. ovens) until it is bone dry - or about 30-40 minutes give or take. If you're really impatient, you can nuke in the microwave for about 3 minute intervals in a microwave safe non-plastic container (your plastic will never taste the same if you use plastic) until it reaches 180-200 degrees according to a cooking thermometer. Also scrub out your plant pot - no bleach dish soap though...

While you're waiting for the dirt to cool, wash your roots with clean water and trim off any mushy parts. Don't pull them off because you could damage the rest of the roots or leave stringy parts behind - a little root trimming can promote healthy root growth if you don't overdo it.

If you see the little gnats, there are many threads and solutions posted on this forum for getting rid of them - I think quite a few were covered here and I know there are many more you can find by searching for fungus gnat specific threads.

Soil you get from the store usually molds if they had pre-moistened the soil at all or if the bag it came in had tiny holes in it to allow the soil to breath when you reseal the bag. Soil needs to breath and it sounds like you might be overwatering or not have good drainage on your plant pot. It's pretty common since the clay pots that are so popular at the store these days either have only one hole at the bottom or are glazed on all surfaces. if you have a friend who does pottery or a local college that does, see if you can beg/bribe (it's amazing what college students will do within reason for free food) someone to make you plant pots with at least 1 hole per inch on the bottom of the pot. I did this for myself and even salt fired, they work better than the terra cotta pots with just the 1 hole for drainage.

-Fen
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