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Re-potting cactii

I've recently re-potted an Optunia Microdasys and after a few days the new compost appeared to have a whitish mould covering it.  It wasn't long before the Optunia started to turn brown and eventually shrivelled.  Is there anything I could have done to prevent this?


  • wild edgeswild edges Posts: 9,371
    The mould suggests the soil was damp and you should really repot cacti and succulents into dry soil and not water for at least a week afterwards. I like to top-dress all mine with grit which keeps the body of the plant away from the soil and keeps it drier but others might disagree and say this carrys more risk of root rot due to the soil staying wet for longer. I've never had that problem though and if you have good gritty soil and are careful with watering I think it's better to have it. It might also be that you had a bad batch of soil if it went mouldy so quickly. What did you use out of interest?
    Tradition is just peer pressure from dead people
  • Many thanks for your comments.  I've just checked the  mix I used and on the bag it says, Cactus and Succulent Focus re-potting mix which contains grit.  I bought the bag from my local Garden Centre and followed the instructions.  However, I've kept the bag in the greenhouse and perhaps it's become damp and picked up some kind of mould.
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