Pruning Victorian box
Question from Ruth:
I have a garden question. Father Clark, who is a dear friend of mine, has very old–maybe 20-year-old pittosporum. It hasn’t been pruned much. When would be a good time to cut it back hard. He has green growth on top of a lot of old wood. Thanks so much. It is going to look pretty bad for a bit until re-growth starts.
Answer from Pat:
Cutting a Victorian box tree or shrub (Pittosporum undulatum) back hard can be done at various times of year with various results. If you cut an old pittosporum back in mid summer, regrowth will be very slow. If you cut it back in fall or spring, regrowth will be more rapid and successful. Pittosporum grows a little differently from many other shrubs since each joint or node will put out numerous shoots, often as many as four or five. If you cut off the top growth down to the next joint the entire thing (with leaves removed) looks like the ribs of an umbrella that has been turned inside out by a strong wind. Between the nodes where these radiating branches occur will be a long straight branch in the middle that leads to another node and so forth. So the query is where to cut it? If you cut the central branch back to the lower node the surrounding branches will take off and grow longer, creating a shrubbier tree. Unlike most trees buds exist under the bark all up and down the tree, so even if you cut in the middle of a branch, it will sprout and produce new growth. This means theoretically that you can cut back an old pittosporum pretty hard and it will bounce back and become a shrub again. Or you can prune it more selectively and maintain it as an elegant spreading tree.