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Rhododendron woes

Hi Gardeners!

I have identified a rhododendron bush in the garden of our new house. 

It it looks very sad however. Several of the branches appear dead with crispy curled leaves. 

Last years buds are still there but have turned brown. New buds have appeared but they haven’t flowered? Also they appear coated in a fine powder (mould?).

I would love to bring it back to life. I have tried to google to see what I can do but it appears that rhododendrons are very picky and a bit of a diva; it could be dying for a variety of reasons. 

If anyone is able to identify what exactly is wrong with it I would know where to start! 

Many thanks in advance!


  • Have you checked the soil acidity(pH)? They like acid soil conditions but only guessing as to weather or not this might be the issue.
  • foxwalesfoxwales Posts: 69
    They like acidic conditions, get some ericaceous soil and try to work in as much as you can down and around the base of the plant and give it a feed regularly with an acidic feed.  You can prune out the dead wood down to live wood to encourage growth now before it flowers if it does.  Alternatively, if your soil is alkaline it maybe better to lift it, prune it and pot it in ericaceous soil, but this may prevent it flowering for a while.
  • FairygirlFairygirl Posts: 52,080
    Can I please correct this. They do not need acid soil. They're perfectly happy in neutral soil.

    It has probably become very dehydrated through last year, especially when buds are being formed [late summer ] and once they get dry, it's difficult to get them rehydrated. 
    How is it planted? It looks like it's in among a load of rocks. If so, it's probably also struggling to get any nutrition and moisture further down. A really thorough watering will help initially. You can prune all the dead stuff out as well. If it's been very dehydrated, it will ditch foliage in order to retain enough moisture for the rest. If there's other planting around it, that will also be competition for moisture/nutrients.

    It looks like it's one of the ones which are rusty brown underneath [on foliage] . They have furry buds, so don't worry about that unduly.  :)
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Hi @Fairygirl. Neither of the comments before yours said that Rhododendrons need acid conditions but said that they like acid soil. The RHS page on growing them in alkaline soil mentions there are some lime tolerant varieties but in general says they grow best in a pH of 4.5 - 6 which is on the acidic side of the neutral pH of 7. I have soil that is mildly acidic and fairly close to neutral and they seem to be growing fine. I don't know for sure from the picture what is causing the opening posters rhododendrons to be in poor health and was just putting forward a possibility that could be tested for and the RHS page I gave a link to would suggest this could be a factor in poor growth.
  • foxwalesfoxwales Posts: 69
    Fairygirl said:
    Can I please correct this. They do not need acid soil. They're perfectly happy in neutral soil.
    Yes, ignore all of the decades of horticultural advice and listen to fairygirl because the exact variety of dendron you have prefers alkaline conditions.  :)
  • FairygirlFairygirl Posts: 52,080
    I'm sorry - but when people say 'they like acid soil', it immediately suggests that they have to have it. Queries about rhodos performing badly is common on the forum - year in, year out, and many people then make this statement about acid soil. 
    The poster before me has said to use ericaceous soil  and feed with ericaceous food. I think that's a fairly clear statement!
    At best - it's misleading.
    The soil isn't the only factor either, in how well they grow or not. 
    If the OP can provide better photos, that will also help. The shrub is starved of moisture and nutrition  :) 

    I stand by what I said, but people are perfectly free to ignore me of course. 
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • debs64debs64 Posts: 4,904
    I have a rhododendron that I discovered last year when clearing a very overgrown area of the garden. It doesn’t look brilliant in my neutral soil but I assumed it was both hungry and thirsty after being swamped by invasive grass for years, the area is cleared and I fed it and am giving it a drink of cold tea every morning as advised by another poster and to my mind it’s looking a bit better every day. Maybe it would be happier in ericaceous soil but it has to put up with what is there, I would be happier on a Caribbean island with Idris Elba some days but that’s life! 
  • GemmaJFGemmaJF Posts: 2,286
    I don't know a great deal about a lot of plants, but rhododendrons are one of my things. The poor thing was not watered last Autumn.

    Nurse it through this year, water liberally in the Autumn. 

    Very little you can do now for this year, other than keep it going.

    It's a strange thing but the watering is very necessary for good flower buds the following year.
  • LiriodendronLiriodendron Posts: 8,024
    As far as I know, no rhododendron "prefers alkaline conditions", @foxwales.  As @Fairygirl says, they NEED neutral soil, and if your soil is acid, all the better.  They are best in a leafy soil which doesn't dry out, in semi-shade.

    @hatty_ - I think that's Rhododendron yakushimanum, or a hybrid of it.  I'd agree that it's almost certainly got too dry, which has caused a large portion of it to die.  The remaining part looks reasonably ok though; this rhododendron has curled leaves with "fur" on the back (and on the new shoots when they open), so that's nothing to worry about.  It won't flower until May, probably.
    Since 2019 I've lived in east Clare, in the west of Ireland.
  • Hi @fairygirl I would not be suggesting people should ignore you and your suggestions for what is causing the problem with the rhododendron is a very valid possibility when looking at the photograph and reading the description of what could be mildew which I have read can be caused in some plants when they don't get enough water. As I said in my first post I was really just making a guess and mentioned it was something that could be tested for.
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