Japanese maple

(Question)

Please advise me how to deal with this green graft on my small Japanese maple tree. Shall I cut it off? I did not realize this when I bought it .

It also got a little overgrown with the cedums. I think I have to transplant it as well as it’s in a corner close to the stairs leading to my front door. When is a good time to transplant and how much sun does it need? Thank you,

(Answer)

Thanks for contacting the Toronto Master Gardeners. Japanese maples are difficult to propagate from seeds and cuttings, so most are grafted. Typically the root stock is from a hardy, less ornamental Japanese maple, and the hybrid with the desired features (leaf shape and colour, etc) is grafted on top. There are a couple of possibilities for the green growth that you are seeing on your tree. I can’t tell from your picture where the green growth originates. It could be growing directly from the root stock, below where the graft was done (look for scars and a thickened area on the truck), in which case this green growth should be removed right down to where it attaches to the trunk. You should check your tree often for these sprouts and prune them all out as soon you notice them. Otherwise they will take over the tree and the branches with the purple leaves will not thrive. If the green growth is on a branch that also has the purple leaves, it could be a genetic mutation, also known as a sport. This is a random mutation that can occur on any plant at any time, and takes various forms including changes in foliage colour. Assuming that the green growth in your tree is not coming from the rootstock, I think you are probably seeing reversion which is a type of sport. Reversion is the name given when leaf shape or colour reverts back to the form found in the plant’s parentage. Usually shoots that have reverted are very vigorous. They should be completely pruned out or cut back to wood containing the desired leaves.

The best time to transplant your tree is in the fall, early enough to allow time for its roots to get established. I think doing this now (mid October) is probably too late, but it all depends on the weather and how long it will be until the ground begins to freeze. The next best time is in the early spring, before your tree starts actively growing again. You will need to pick a new spot for your tree that will accommodate its height and width at maturity. Depending on the variety, Japanese maples grow in full sun to almost full shade. Most do best in partial shade with protection from hot mid day sun. I can’t tell from your picture, but based on what I can see of the current location of your tree, it looks like you might have a dwarf variety. Here is a response from the Toronto Master Gardeners about transplanting a dwarf Japanese maple that you might find helpful.

Transplanting a Dwarf Japanese Maple

Good luck with your beautiful Japanese maple !