Why Is My Plum Tree Not Flowering?

A plum tree that produces no flowers at all each spring is in some ways a different problem from one that flowers but fails to fruit. When there is no blossom, something is preventing the tree from completing flower bud formation during the previous summer and autumn. Several distinct causes can produce this result, and most of them are fixable once you know what you are dealing with.

Tree is still juvenile

Young plum trees on dwarfing or semi-dwarfing rootstocks typically begin flowering at three to five years from planting. Trees on vigorous rootstocks such as Myrobalan may take longer. If your tree is young and growing healthily with plenty of new shoot extension each year, it is simply not yet mature enough to flower. This is normal and no cause for concern — continue routine care and expect the first blossom as the tree matures and growth rate moderates naturally.

Bullfinch damage to flower buds in winter

Bullfinches are a frequently overlooked cause of absent blossom. In winter, bullfinches systematically strip flower buds from plum, cherry and pear trees, working along each branch and eating the fat, rounded flower buds while leaving the smaller, pointed leaf buds intact. A single pair can remove buds from an entire tree in a week. If your plum had flower buds in November but no blossom appears in March, walk beneath the tree and check for discarded bud scales on the ground. Bird netting is the only reliable protection in areas where bullfinches are present.

Excess nitrogen suppressing flower bud formation

Flower bud formation is triggered partly by a mild stress signal — when the tree is growing vigorously on high nitrogen it remains in vegetative mode and does not form flower buds. If your tree makes very long new shoots each year (more than 60 cm) and produces no blossom, reduce or eliminate nitrogen-rich feeds entirely. Apply sulphate of potash in late winter instead, which encourages flower formation without stimulating leafy growth. Allow grass to grow under the canopy rather than cultivating the soil, as this competes for nitrogen naturally.

Biennial bearing — off year

Plum trees can fall into a biennial bearing pattern where they flower and fruit heavily in alternate years and rest in between. In the off year the tree produces no blossom at all. If your plum has this regular every-other-year rhythm it is the classic pattern — see the dedicated biennial bearing guide for how to break the cycle.

Root restriction or deep planting

Trees planted too deeply — with the graft union buried below soil level — grow vegetatively but may not flower. The stem below the graft union suckers enthusiastically and the canopy above does not receive the correct hormonal signals for fruiting. Check that the graft union (the slight swelling near the base of the trunk) is 5–8 cm above soil level. If it is buried, carefully remove soil from around it and maintain the correct planting depth going forward.