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Lincolnshire, United Kingdom Gb

Dear all!

I bought a Hydrangea Macrophylla 'Zorro' last summer with lovely blue flowers and during the summer it gradually turned pink. I discovered I needed to add Aluminium Sulphate. I didnt do this over the winter but a week ago I pruned the plant back to healthy looking buds, water with Aluminium Sulphate and top dressed with multi-purpose compost. I looked today and the buds have lost most of their lovely green colour and outer leaves are crisp to touch as if it is dying. Have I done something wrong? The plant is in a pot 14" deep and 14" round. Regards



One thing you've done wrong is prune too early - Hydrangeas shouldn't be touched before April, and late April at that in colder regions, so that any frost which occurs catches the dead tips and spent flowerheads from last year rather than the new growth beginning to appear. Even so, new growth on Hydrangeas is often nipped by frost - it usually goes crispy black rather than brown though, so are you sure you diluted the aluminium sulphate to the right strength? I have to also suggest that, as the plant is in a pot, I wouldn't have used aluminium sulphate, which is really designed for use on open soil - much easier to use ericaceous compost in a pot.

24 Mar, 2011


Bamboo, Thanks very much for your reply and advice. Would covering them with fleece etc help them at this stage or do you think damage is done and I should cross my fingers a hope it recovers? Also should I re-pot using ericaceous compost or will top dressing suffice? Regards

24 Mar, 2011


I'd repot completely, just in case the aluminium sulphate was too strong or something - covering when you know its going to be frosty overnight would help, but remember, even if it gets nipped by frost, it won't kill the plant.

25 Mar, 2011

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