Help with Acer die-back - do I prune it? Repot?

Hi,
I am a new member. I garden around the edges of a shared garden, mainly in pots & raised beds.
I have an Acer which is about 4 years old in a large but shallow pot (45cm wide, about 25cm deep), I bought the tree very small and it's now about 1.5 m high and was doing great until this year.
This summer (which was obviously very hot) it struggled and most of its leaves fell off (in the summer). Much of it looks quite dead. Late in summer it shot out some new branches from near the base.
Any advice on how to rescue it? Should I cut out all the deadlooking branches (probably about a third of the tree)? Should I repot it? When should I do this?

Thanks so much for any advice!

 

Give it a deeper pot and some good quality compost so the roots can grow deeper and stay cooler in hot weather. Do that as soon as possible as roots still grow over winter.

Composts for planting only have nutrients for about 90 days so make sure you give the pot an annual top dressing of slow release fertiliser every spring and use a liquid fertiliser in between plain water thru the growing season. Never let the compost dry out but make sure you're not drowning it either.

Once leaf drop is complete and you can see the stems clearly, remove any dead, diseased or damaged wood and any crossing stems of branches that may rub each other and cause injury.. Do this while the tree is dormant and before the sap starts to rise in late January.

Finally, adjust the shape if needed in late spring or early summer once you've seen how it's growing and after the initial burst of spring growth when the flow of sap is strongest. You need that to have slowed down or the tree can bleed to death if sap flow is too strong.

 

They do bleed so unless pinching out new shoots I wouldn't do any pruning after january.

 

Great thank you. I will crack on with that.

 

Aren't a lot of Acers grafted? Is it possible that the new growth from near the base is from the rootstock?

 

That is a possibility @katecat58 but can't be known till the new leaves are compared with what the original leaves looked like. I hope @sheffield_kid has a photo or the original label.

 

When you repot your Acer @sheffield_kid, avoid using multi purpose compost, especially if it’s peat free. Ideally, use a soil based ericaceous compost, mixed with some composted bark in a ratio of 50/50, plus a few handfuls of horticultural grit. These are all usually available in good garden centres or DIY stores.

 

Its leaves have all dropped now and I can't find any good pics from back in the summer, it was looking sad so I don't think I was photographing it much. I've attached one pic but it's not great. That was around June. You can see the top leaves had all gone.

The new growth from the base was in late summer/autumn - it produced some leaves - the leaves were the same as the rest of the tree.

Thanks for the advice everyone. I can't remember what I planted it in years ago the soil advice is very helpful!

 

I’ve seen worse, @sheffield_kid. That’s quite a small pot for the size of tree though. I’d follow the advice on repotting, especially the bit about the ericaceous compost. Acers do really well in our garden here, where we have very acid soil.

 

Is it in a windy or exposed location?
If it is, then sun and winds will dry the leaves causing leaf damage and icy winter winds may damage tender shoots and branches.
Although the red varieties fare better in the sun and wind it's not what they like.
In their native environment they thrive at the edge of woodland under dappled shade from trees.

It would be a good idea to raise the pots a little from the decking (pot feet or something similar).
They prevent waterlogging of the compost during winter months which may rot the roots.

 

Not much to add apart from if it's been in the same pot for 4 years, they tend to have so much root, that keeping them moist is very hard. I have seen them where there is virtually no soil left at all to hold water.
In bonsai they root prune them every couple of years or so, if they are staying in the same pot. I'd pot it on personally to a pot an inch or two bigger on all sides.

 

Ok mixed messages here. Most are correct, not all.
Yes use soil based compost, ericaceous is preferred but not essential. JI 2 is ok , Acers have very fine roots so not too much grit, and they are not very heavy feeders
Yes they are woodland edge plants, so some protection from wind and excessive sun is better.
Now the big one..... If only I had a pound for every time I have had to say this.....
The Japanese prune Acers, IN ALL FOUR SEASONS if they require it. Except very early spring when the sap is rising. Large Structural pruning is done in winter, but further trimming and shaping can be done after April and through the summer, so long as you are not cutting anything thicker than a pencil. Use straight cuts with fine snips or even better bonsai clippers.
They are relatively slow growing so if there is space they can be left, they naturally "shed" branches dieback is usually obvious, much paler or even white. If you are unsure scrape a little bark in, if it's not green underneath it's dead and can be removed at any time.

 

Right - I've got a day off work and it's not as cold today and I'm cracking on with this. I'm taking a break for a cuppa and more advice.... So, I bought a bigger pot, and I've repotted it in a mix of ericaceous and john innes no 3 compost. It looked quite root bound. Here's some pics. Right don't tell me I've done this wrong because I've done it now haha. Pruning next...

 

Pruning - help.

So I've cut off all the little branches which appear to be dead. Some branches already have little buds on for next year so obviously leaving all those.
But, the MAIN BRANCH appears to be dead. Do I cut off half the tree???

I've attached some pictures of the dead looking bits, the live looking bits, and the whole tree with the main dead branch circled. Sorry the pics aren't great it's not that easy to photograph a leafless tree in winter!

 

I wouldn't be overly worried about pruning any suspected dead bits yet because it won't do any harm to leave them on until spring when you will get confirmation of if they are really dead.

Is that pot much larger than the original. Normally you would go for one that is only an inch or so larger all round when potting on because maple don't like wet roots in winter. You will likely be fine but it might be worth raising the bottom of the pot up a little to help with draining this winter.