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I have had this Magnolia soulangeana 'Heaven Scent' for 2 years (I live in South East England). It is in a cubic pot (of side length ~50cm) on the patio and is currently 135cm tall.

It did very well in its first year and it also bloomed well in early spring this year. It seems to have grown significantly since last year.

However, the leaves have now just started to brown and curl (see 5 photos below), which seems surprising in early July. Also (possibly related?), something has eaten some of the lower leaves (see image 4).

What could be causing these problems?

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EDIT: Regarding the holes, the insect pictured below may be a possible culprit. It looks like a moth that has just hatched and cannot fly, only jump. I cannot see any distinctive wings, so they may not have developed yet.

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  • When you say a 50cm 'cubic' pot, do you mean a pot that's shaped like a cube? Are you able to add a photo showing the whole plant and its pot? Do you know which variety of magnolia you have? Lastly, can you check beneath the leaves and on the stems to see if there's anything that shouldn't be there - I can see some webbing on top of one of the leaves
    – Bamboo
    Jul 3, 2020 at 12:35
  • @Bamboo It's a Magnolia soulangeana 'Heaven Scent' and, yes, I meant a 50 × 50 × 50 cm pot. I have edited my question and added more photos, as requested. Which photo are you referring to when you mention 'webbing'? Jul 3, 2020 at 14:26
  • Third picture down, leaf slightly to the left about half way down, just below the top, severely browned and curled leaf in the centre. There's webbing towards the top of that leaf - there may be more elsewhere, suggests caterpillars of some sort maybe, but check beneath the leaves.
    – Bamboo
    Jul 3, 2020 at 16:00
  • @Bamboo I think you may be right about there being caterpillars. I found what I believe to be some sort of moth on one of the leaves, possibly just hatched as it cannot fly, only jump. I will add photos of this at the end of the question (although I may need a second question about identifying this insect?). Is pruning the damaged leaves the best course of action? Jul 3, 2020 at 16:31

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Magnolia soulangeana 'Heaven Scent' is a fast growing, deciduous small tree, reaching anywhere between 6-8 metres tall. Although you've only had it in that pot for about 18 months, it's probably outgrown the pot already, which might explain some of the brown, curling leaves. If it has outgrown its pot, the pot will be full of roots with not much soil left around them, and that means it will need more water more often because the roots can't hang on to any moisture for long. If it gets sun, then May in the UK will have been difficult for it, given the unusual heat and constant sunshine, particularly in the south east.

You can check whether there any roots venturing through the drainage hole/s in the bottom of the pot, otherwise you will need to turn it out of its pot to check if it's root bound, but unless it's really badly root bound, repotting into something larger is probably best left till autumn, though in truth, the plant will do much better planted in the ground. Magnolias don't like root disturbance, so the need to pot on into something larger every year or couple of years without causing root disturbance isn't easy.

I would think, judging by the webbing on that leaf and the number of holes on the plant's leaves, a moth laid its eggs on it, and the hatched larvae will have been responsible for the little holes, but by now, most will have hatched out into moths and will leave the plant. Many moths lay their eggs in webbing on plants, so I doubt this moth is specific to magnolia. You can clip off any badly browned leaves, but don't take any you don't need to - Magnolias aren't too keen on being pruned either, though removing a few damaged leaves won't be an issue.

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  • Thank you very much for this comprehensive answer! I think, as you suggested, we do need to plant it out, but we do not have a suitable spot as yet in the garden. If we do repot in the autumn, how much bigger should the pot be in order to keep the plant going for another 18 months before we plant out? Jul 3, 2020 at 16:56
  • Probably twice the size of the one its currently in, if you want to leave it in it for 18 months. Best planted out in autumn in the UK, by the way... also shallow rooting, so don't plant somewhere you frequently need to dig round it.
    – Bamboo
    Jul 3, 2020 at 17:01

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