Uh oh...mold?

9 years ago

When I woke up this morning I checked on my plants and noticed that some yellow stuff has seemingly popped up overnight. I've attached a few pictures of it below.

I don't know what it is (possibly mold? fungus) but it is beginning to spread, taint the perlite/white marble gravel and I'm fearful that it will hurt the plants. This same yellow stuff has also popped up on the soil that my cactus seeds are in.

The soil that I'm using for all of the plants is Miracle Gro Cactus/Succulent Soil mixed with perlite. Could I have avoided the mold (if it is mold?) by microwaving the soil before planting? And is there any way I can save my plants/cactus seedlings? Maybe by repotting? I'm really worried about my plants :-(

Note: I know the plants in the 2nd picture don't look too great but that was how they looked when I rescued them from the ground of a Walmart. I asked if I could take them and an employee there said yes, since they'd be just thrown away anyway.

Featured Answer

rina_Ontario,Canada 5a

9 years ago

It happens with wet soils very easily. I don't think it will hurt your plants (at least not right away), but wet soil will and probably faster.

If using MC C&S bagged soil, it is best to mix it with lots of perlite - what is in it is negligible. Add minimum 50%, and more would be better (60-75%) of sifted perlite (or pumice, if you have any).

If my plants, I would take hem out of soil they are in. Get rid of all of it from plants roots, and check if the roots are healthy. They could be already damaged by too much moisture. Cut off any slimy, black & soft, or dry and/or broken roots. Repotting into better mix and containers with drainage holes should be done ASAP IMO.

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Comments (7)

Lois (Zone 4a, Minnesota)
Original Author
9 years ago
Thank you for the advice. I have started to repot some of the plants with a good mix of ample perlite and the Miracle Grow cactus/succulent soil. Unfortunately when I started all this a week or so ago I was too trusting of their "fast draining soil", lesson definitely learned there.

What would you suggest I do with the cactus seedlings? Should I take out the ones that have germinated and repot them in new soil as well?
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rina_Ontario,Canada 5a
9 years ago
Lois

Good luck with repotting :)

I realized that I didn't answer your question about 'nuking' the soil - it would probably help if you are sure there is 'infection' of some kind in the soil. It is possible that soil was stored wet, and fungus grew on it. Sorry this isn't better answer - I never nuked soil (and do not use it for succulents either). Maybe someone else will offer some suggestions.

It's unfortunate that MC C&S soil is not as well draining as advertised...that's why it needs to be heavily amended. Many ppl use that mix (lots of perlite or pumice (minimum 50% or more +soil) and seem to have good results.

All cacti should be also in well drained mix. They are succulens too. They often need even less watering than other succulents, and definitely very good drainage.
Shawna (5a WI,USA)
9 years ago
When I get mold, I spray with hydrogen peroxide.
rina_Ontario,Canada 5a
9 years ago
last modified: 9 years ago
I believe that would help, but it is 'First Aid', and in the long run, it is best to figure out why there is mold in the first place. It indicates conditions are god for it to grow - most of the time wet and organic mix/soil - and that is not good for plants.
Shawna (5a WI,USA)
9 years ago
last modified: 9 years ago
Agree with Rina, too. Occasionally I've needed first aid for a short term issue. e.g., Propagated babies in plastic egg cartons (yes with lots of drainage holes) in gritty mix, bottom watered -- and plants of different sizes absorbed different amounts of water, and thus got a little mold in a couple spots with tiny plants. Hydrogen peroxide got rid of mold until I transplanted.
rina_Ontario,Canada 5a
9 years ago
Shawna - it is good to know 'first aid'! Just wanted to make sure it is not relayed upon all the time...If humid environment, small fan is also helpful.