I transplanted some very young mimosa trees this spring and I would like to prune them all to the same height. They seem healthy. When would be the best time to do this?
The Gardener’s Answer
Hello, Jim: Mimosa trees (Albizia julibrissin) are very tolerable of most growing conditions. They provide a topical look for those of us not gardening in the tropics but they are not without their negative aspects. They are non-native trees that are short-lived and are prolific at self seeding. Mimosa trees should not require any annual pruning except to remove any dead, diseased, or broken branches. If you want to prune them spring would be the best time, although they are fast growers and will eventually all reach the same height, approximately 25-30 feet. I would suggest that you just give them time to catch up and they will. Unfortunately, mimosa trees are very susceptible to insect and disease problems, specifically a vascular wilt disease. There are a few cultivars that are wilt-resistant, including ‘Flame’ and ‘Union.’ If yours were transplanted from a roadside or waste area they are likely not a resistant cultivar.