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Cactus turning black at top

Hi. I just noticed my cactus is turning black at the top and the bits where the spikes come out also look dark. Is it rot? I've read that if the top is rotten you chop it off but do the black spikes mean it's so the way to the bottom?

It grows next to a south facing window. Hasn't been watered for ages.

Thank you in advance for any advice!



  • I didn't even know about the two little ones-they're behind the main plant. I think they're completely dead-very dry and hollow.
  • MikeOxgreenMikeOxgreen PenninesPosts: 606
    What kind of compost is it in and is it dry throughout? When was it last watered?
  • It's in the compost it came in-we didn't repot. It hasn't been watered for months. 
  • DovefromaboveDovefromabove Central Norfolk UKPosts: 82,262
    Has it been between the curtains and the window on recent cold nights?
    “I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh

  • No it hasn't - there's no curtain. The two little ones have been dead about a year but the damage to the big one is about a month old. That's when we had the cold snap. Is it cold damage? Thermostat is set to 16C but by the window...
  • MikeOxgreenMikeOxgreen PenninesPosts: 606
    You need to find out what it is, some Cacti are incredibly resistant to cold (if dry), some are not. If it's a Cereus then they only go down to about 10c.
    Make sure someone hasn't been watering it behind your back.
    They need to be in proper cactus compost, not the crap they often get sold in.
    It looks like there is one remaining plant which is ok if I read your pics correctly, so part that off, find out what it is and look after it accordingly. 
  • Balgay.HillBalgay.Hill Posts: 850
    edited 8 January
    As Mike says, you have nothing to lose by repotting the 'good' section in proper soil, and don't water it until March.
    Your soil looks quite damp, so might someone else have been watering it?
    Sunny Dundee
  • FairygirlFairygirl west central ScotlandPosts: 49,143
    As it's inside another 'smarter' pot, has it got enough drainage from the pot it's in?
    It may seem obvious, but it could be sitting permanently in water. 
    It's a place where beautiful isn't enough of a word....

  • McRazzMcRazz Posts: 144
    It doesnt look like under-water damage as you'd expect the entire plant to be displaying stress and obvious symptoms like shrinkage/wrinkling.

    My moneys on over watering (by someone else?! My OH is a nightmare for this), or cold damage. 

    Maybe the larger stem was leaning against the window glass?

    We've lost a few plants in our bathroom where the window has been left open on cold days/nights. 

    If overwatered I'd expect the top to be all squishy like a baked aubergine.

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