DO'S AND DON'TS OF PRUNING OR TRIMMING JAPANESE ACERS / MAPLES

I never pretend to be an expert gardener, far from it (I guess some of you have guessed that already) but I have been gardening a long time and while I still make plenty of mistakes (as do the experts), I do try to learn by them.  One lesson learned was the other year when I decided to trim, just a little tidying, snip snip snip, of a Japanese Maple in spring.  It was the lovely Acer palmatum 'Katsura' and I just cut away a few straggly bits at the tender young ends of stems and the next thing you know it was 'Aphid Invasion from Outta Nowhere'.  You see, what I should have known, or remembered, was that at that time of year the sap is rising in trees and shrubs, and trimming just caused that sticky sap to leak from the wounds — and don't sap-sucking aphids just love it!  The poor shrub had thousands of black aphids stuck all over it in great big clusters, and while I tried squashing them I finally had to resort to blasting the little suckers with the hose.  The poor shrub looked miserable.  So did I.



Acer palmatum 'Katsura' - May 2018

This year, in spring, when I transplanted Acer palmatum 'Katsura' from a container into the garden border it did have some straggly bits sticking out but I just left them.  Results: No aphid attack.  What I did do was trim away any dead growth but I did not dare cut into live wood.  Anyway, the plant seems very happy and healthy in its new home now, thank you, and I hope it remains so. 

Acer palmatum 'Katsura' - late July 2018

Another Japanese Maple called Acer shirasawanum 'Jordan' is unshapely.  It is an upright shrub and has beautiful bright green leaves right now but it has three very long branches sticking out and I am dying to get at them with my secateurs and cut them back somewhat.  I want to encourage more growth lower down.  But I shall wait, remember my lesson, and do it when the shrub goes dormant in winter and sap is no longer rising.

Acer shirasawanum 'Jordan'

I also plan to find Acer shirasawanum 'Jordan' a new home, in the ground.  I read so often that Japanese maples don't like exposed and windy areas, or severe winter cold, but then I also read that they survive much better with their roots in the ground where the roots are warmer in the winter than they would be in a container, and where they are less likely to be in danger of drying out, and also where they are less likely to suffer from lack of nutrients. Oddly, perhaps, I have noticed some leaf damage half way along those long shoots, and then very healthy growth after that.  I've not figured out why that has happened but anyway it's good to see it's healthy enough otherwise. 



By the way, watch out for that infernal and destructive vine weevil larvae which destroyed a lovely shrub of mine, Acer palmatum 'Orange Dream'.  Many years ago, vine weevil larvae destroyed all my fuchsias.  The trouble is, they are sneaky little blighters as they eat away the roots of plants and you don't know it's happening until it's too late.  There are chemicals for that, such as Provado 500 Vine Weevil Killer2, however. 



One Japanese maple, Acer palmatum 'Phoenix', in the image below, has been, so far, trouble free.  I like the shape of it, but I also want this to go into the ground before winter.  Finding places to plant shrubs in my garden is not an easy task as I have a heavy clay soil which is also riddled with sandstone.  I think, at some point way in the past, before the house was constructed, that someone flattened a drystone wall and just spread a few inches of soil on it.  My lawn grows remarkably well consider there is a soil depth of only an inch or two before there is rock.  So digging a hole for shrubs is not something to look forward to.

Acer palmatum 'Phoenix' - late July 2018

In a nutshell, if you want to prune Japanese Acers / Japanese Maples, do it when they are dormant in the winter months.