Why Is My Plum Tree Not Producing Fruit?

A plum tree that flowers beautifully every spring but never carries fruit to harvest — or one that simply sits producing nothing at all — is one of the most frustrating problems in the kitchen garden. The cause is almost always one of a handful of well-understood issues: frost at flowering time, pollination failure, youth, over-pruning, or the wrong growing conditions. Working through the checklist below will usually identify the problem within a season or two.

Late frost killing the blossom

Plum trees flower very early — often in March or early April — which puts them squarely in the frost window. A single night at -2°C when the flowers are open will kill the entire blossom crop without damaging the rest of the tree. The flowers turn brown and fall without developing into fruitlets. Growers often blame pollination failure when the real cause is a frost they slept through. If you are in a frost pocket, fan-training a tree on a warm south or west wall offers substantial protection and usually produces fruit when open-grown trees fail.

Pollination failure — self-fertile vs. cross-pollination

Some plum varieties are self-fertile and will crop alone; others require a compatible pollinator planted within about 50 metres to set fruit. If you have planted a single self-sterile variety such as 'Marjorie's Seedling' without a partner, and there are no other plum or damson trees nearby, flowers will open, be visited by bees, and fall without setting fruit. Check your variety's pollination group in a reference guide and plant a compatible tree in the same or adjacent group.

Tree too young

Grafted plum trees on semi-dwarfing rootstocks typically begin fruiting at three to five years old. A standard on Myrobalan rootstock may take seven or more years before bearing fruit reliably. If the tree is young and healthy, patience is the answer. Avoid heavy nitrogen feeding in youth — it promotes lush vegetative growth at the expense of flowering.

Over-pruning or incorrect pruning

Plums fruit on both old spurs and one-year-old wood. If you have been removing all new growth every year in a misguided attempt to keep the tree small, you are removing the wood that would carry next year's fruit. Plums need light pruning in summer — primarily removing overcrowded, diseased or crossing branches rather than shortening all new growth.

Too much nitrogen

High nitrogen feeds push trees into vigorous vegetative growth — long, leafy shoots with no flowering incentive. If the tree is making metres of new growth annually but not flowering, stop all nitrogen feeding and let the tree settle into more moderate growth. Potassium (sulphate of potash) applied in late winter encourages flower bud formation.