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Emery Davis[_3_] · 08-05-2011, 11:40 PM posted to uk.rec.gardening

On 05/08/2011 09:32 PM, wrote:
Emery, we have a splendid 2.5 metres tall Sango kaku in a 50 cms cube
container. Your remark above concerning the need for root pruning has
given me food for thought. Given the current rate of growth it occurs
to me that it will quite rapidly outgrow the container and that we
probably made a mistake by not planting it in the open ground.

If you concur with this when would be the best time to move it, autumn
or next next spring?

Hello rbel,

Normally I like to plant out in autumn from containers. (I grow most
young grafts or seed grown maples for 2-4 years in containers before
planting out.) This gives the roots a head start and eases the watering
chores for the following year. But Sango kaku is an exception, because
it is extremely prone to pseudomonas bark infections in our wet winter
climates. So for that one I'd plant out in spring, and make sure I
could provide regular water for the 2 years it will take to establish in
the landscape.

Make sure you have really free draining soil to put it in, but with a
good water source, if you can't provide that it might be better to leave
it in the container. Although it's quite popular Sango kaku can be a
really tricky maple to grow if the conditions aren't ideal. It does
deal well with sun but if that's a change it may experience some die back.

I have a couple in the ground currently and none in pots, but if I had
one that was performing really well in a container I'd be tempted to
leave it there. However there's no question that ultimately, if it can
make the transition, it will do better in the ground. For now, you
could take a look at the roots and see how it's doing, container maples
don't seem to mind this.

HTH,

-E