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Mimosa tree pruning guide

#1 · 9th November 2022, 1:48 pm

Hi, I have a mimosa tree in my garden which is growing rapidly, it is now up to the bathroom window. Unfortunately it is not a robust specimen. Although it is budding up to flower the trunk is not strong enough to stay upright! With winter coming I need suggestions about what to do... should I chop it down to half the height in the hope it will be more stable? Or should I tie it to the bathroom window till after it has flowered then be brutal?

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#2 · 10th November 2022, 12:24 pm

Hello MGB,

Your tree may be cut back after flowering, so look to prune in May, June or July, the next seasons flowers are formed in autumn, so do not prune after late summer, any damage from frost lightly trim the branch back to good wood in spring, as you have found out, these are fast growing trees.

Bob

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#3 · 14th November 2022, 8:07 am

Quote from mgb on 9th November 2022, 1:48 pm
Hi, I have a mimosa tree in my garden which is growing rapidly, it is now up to the bathroom window. Unfortunately it is not a robust specimen. Although it is budding up to flower the trunk is not strong enough to stay upright! With winter coming I need suggestions about what to do... should I chop it down to half the height in the hope it will be more stable? Or should I tie it to the bathroom window till after it has flowered then be brutal?

Hi @mgb

The Mimosa or Acacia dealbata is a super fast-growing evergreen tree. With gorgeous yellow flowers in summer. Due to its rapid growth of up to 12m it can get leggy.

It sounds like you're could do with a decent hard prune to help it bush out a bit more and stop reaching for the stars! If the main trunk of your Mimosa tree isn't strong enough then its a sure sign that its not had the right formative pruning to help it grow into a stronger shape or form.

I wouldn't tie it in to the bathroom as it won't help strengthen it, which it sounds like it needs. Like Bob says, if you don't want to lose the flowers, prune after it flowers in early summer. However, I would caveat that with the chance of it getting damaged if too tall and weak. It may be best to prune it now to reduce its height and miss one year's flowers. mimosa trees are not fully hardy, so can suffer from frost damage. So it may be worthwhile pruning it back now.

My pruning guide here should help.

Other than that, Mimosa trees are pretty bulletproof, so enjoy!

Happy gardening

Lee