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Mildew /mold on red stonecrop sedum

Mariam_86Mariam_86 Posts: 79
edited July 2021 in Plants


I have two red sedums planted in one pot (around 25cm wide). 

They were doing great until a week ago when I noticed they were covered in mold and the leaves were dropping off. 

I don’t water regularly and have never fed - could it be that the two plants need to be spaced out? 

Could anyone please explain what could have caused this and what I can do to prevent this happening again?

Healthy photo was taken toward end of June, the second photo was taken today. 

I think I posted the before on Gallery forum under my old username! 



  • PalustrisPalustris Posts: 4,104
    I would check that there are no vine weevil grubs in the soil first of all.
  • Mariam_86Mariam_86 Posts: 79
    Thanks @Palustris - I just checked by tipping out the plant from the pot and I can’t see any. I’m assuming they would be easy to spot if they were present. 
  • philippasmith2philippasmith2 Posts: 2,943
    Not necessarily as they will burrow deep into the actual root structure.
  • FairygirlFairygirl Posts: 52,081
    They really love sedums.
    I managed to introduce them into this previously weevil free garden by buying a sedum which had them  :/

    Hopefully they're just needing a bit more water. Although they like dry conditions, they still need some water when in pots - especially clay pots. 
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Mariam_86Mariam_86 Posts: 79
    Thanks all. I just checked again, loosening the soil around the roots. Couldn’t see anything. Are they particularly hard to spot?

    Is mildew related to vine weevil? 

    Should I cut the plant back? Or just let it recover on its own?
  • PianoplayerPianoplayer Posts: 624
    As Fairygirl says, the most likely cause is lack of water - plants that are water-stressed are prone to powdery mildew.

    Vine weevil root damage is really noticeable as the plant is completely wilted, and can be lifted off the soil with no roots.

    If it was mine, I would water it generously, and see if it recovers. You could trim off the worst bits.
  • Mariam_86Mariam_86 Posts: 79
    Thanks! Will do. 
  • BorderlineBorderline Posts: 4,699
    edited July 2021
    I'm looking at your second photo and cannot see any sign of powdery mildew. The leaves looks like possible light aphid attack at one point. They don't need feeding of sort, and feeding may have made them grow excessive and soft, which can invite aphids. 

    If you are watering, water from around the base and avoid watering over-head. These low growing ones are not as robust with excess water.
  • Mariam_86Mariam_86 Posts: 79

    @Borderlinehere’s a close up.

    I haven’t fed at all and rarely water since it’s been raining this summer. There was definitely what looked like powdery mildew on most of the leaves last week, most of which have fallen off.

    I don’t think it’s aphids as there’s no sign of aphids or ants. 

  • BorderlineBorderline Posts: 4,699
    Thanks for the closer photos. Is this Sunsparkler 'Wildfire'? If so, at this time of year, they do not retain their looks and when flowering starts, they are more of less losing their leaves. I still don't believe it has anything to do with powdery mildew. This is my opinion. I have grown these before and found them disappointing around late summer. If you cut them back now, new leaves can form, but all uneven and the colour lost. 

    Sedums are usually easy to look after, so I don't think you have done anything wrong to end up with this issue. Only thing I can say is, they need really free draining soil unlike the taller and bigger Sedums. They also grow quickly and not their best when they start to flower, so I think you should prune back for them to grow back more compact.
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