Pruning Japanese angelica tree
The Japanese angelica tree is a magnificent tall plant that should be pruned as little as possible. If you do want to remove any of the larger branches, the best time to do this is in winter, as the soft wood is then less likely to rot.
The tree can be renewed completely over a period of three years or more. Do not start at the outside but cut a third or a quarter of the thickest branches in the middle of the tree back to about fifty centimetres. These branches should preferably be cut back to an outward facing eye or bud.
The next year you can remove half or a third of the remaining branches in the same way. The number of branches removed depends on how many years you want to spend on completely renewing the tree. Keep on pruning the older branches every year until the tree has been completely rejuvenated.
The Aralia has a tendency to develop root suckers. These can be cut back hard from March to September, although you should realize that drastic pruning will encourage the development of new suckers which will in turn need to be removed. Even so, it is best to remove these root suckers if you want the tree to retain its handsome appearance.