white fur growing on soil.

[Laurenyeah]

hi all.
i am new to getting some indoor windowsill cacti
(please forgive if i am getting any terminology etc wrong, as i said i am just starting out!)
one of my cacti has white fluff / fur growing on the soil but not on the plants
i have watered them all the same, and have not watered lots.
this has also happened on one of my succulents, as i said they have all been given the same.

thanks!!
lauren

[greenknight]

That's mold. It's a sign that there's too much organic matter in the potting mix. The mold itself may be harmless (though some types could attack your plants), but the organic matter holds too much moisture, the soil will stay wet too long. See: http://www.cactiguide.com/growcacti/ , and browse the Cultivation forum for more info on potting mixes.

[Ron43]

I have used Lysol bathroom spray for that problem. I usually don't have mold problems, probably because I always lightly bottom water and rarely water from the top.

[williamsii823]

Lysol Bathroom Spray????? 8(

[DaveW]

A plant fungicide would kill it.

As Spence says it is because the organic matter in your soil is actively rotting. It is best not to use actively rotting ingredients in terrestrial cactus soil though it may be OK for epiphytic cacti. Plant detritus in terrestrial cactus habitats seldom actively rots, but just dehydrates and turns to dust, as in the dust example around this dead plant from the Atacama in Chile.

dust.jpg (185.58 KiB) Viewed 3805 times

[Ron43]

Lysol Bathroom Spray????? 8(

Yes! I've used it for years. It's the deodorizer spray. It is also good for powdery mildew. Another solution for powdery mildew is a mix of 1 part milk and 3 parts water and spray the mildew.

[williamsii823]

Yes, I've heard of the milk and water for powdery mildew. Lysol, huh? Intriguing!

[7george]

If the soil drys fast enough mold wouldn't develop. If your windowsills are getting colder now it's time to stop watering for the winter. And that soil might be for change.