Growing Cherry Plum (Prunus cerasifera): Fruit, Grafting, Chill Hours and Care

Cherry plum (Prunus cerasifera), also sold as myrobalan plum or purple-leaf plum, leads a double life. In most gardens it is planted as an ornamental — a fast, deciduous tree grown for deep purple foliage and a cloud of white or pink five-petalled flowers in spring. But it is also a genuine fruit tree, carrying small purple plums of 1–3 cm with a small stone, and those two identities are the reason people end up confused about why their tree does, or does not, produce anything worth eating.

Why some cherry plums fruit and others never do

The single most common complaint about this tree is a beautiful specimen that flowers and then gives nothing. There are two separate causes, and it is worth working out which one you have before reaching for the pruning saw.

1. Not enough winter chill. Cherry plum is a deciduous stone fruit and it needs a set number of chilling hours — accumulated cold in winter — before its flower buds will break properly. In a warm climate that never delivers that cold, dormancy is never fully released: bloom is thin, late and scattered, buds drop instead of opening, and the tree sets little or no fruit no matter how well you feed and water it. This is the reason a cultivar that crops heavily in a temperate garden can be permanently barren a few hundred kilometres south. No amount of care substitutes for the cold; only choosing a lower-chill selection does.

2. The tree was selected for leaves, not fruit. Many nursery cherry plums are ornamental forms chosen for purple foliage and flower display. Some of those bear reliably, some crop lightly, and some are effectively decorative. If your climate does supply chill and the tree still refuses, the plant itself is likely the limitation — and that is what grafting solves.

Purple leaves, green leaves, and what the colour actually tells you

Cherry plum leaves are purple most of the time, but they can be green, and gardeners read far too much into which they have. The honest answer is: leaf colour tells you very little about the fruit.

• A green-leaved cherry plum still carries purple fruit. The two traits are independent — you do not need purple foliage to get purple plums.
• Purple-leaved forms can be grown on green-leaved stock. Grafting a purple selection onto a green-leaved cultivar is standard practice, so a tree can perfectly well be green below the graft and purple above it.
• The growing requirements are identical. Purple-leaf cherry plum wants exactly what any other cherry plum wants — same soil, same water, same light, same chill. There is no special regime for the purple form.

Where leaf colour is a signal is in seedlings. If you raise a purple-leaf tree from seed and the seedling comes up green, you have proof that it is not a copy of its parent — and that is the moment to consider grafting.

Do you need to graft a cherry plum?

Not as a rule. A cherry plum on its own roots can flower and fruit perfectly well, and plenty of garden trees have never been grafted. Grafting becomes the answer in three specific situations:

1. The tree does not fruit. If chill is adequate and the tree still gives nothing, graft a scion from a known fruiting cherry plum onto it. You keep the established root system and trunk and simply change what is growing on top.
2. You raised it from seed and it did not come true. Seed-grown cherry plums are a lottery: the seedling may be green-leaved when you wanted purple, or may carry fruit that is smaller, later or poorer than the parent’s. Grafting is the correction.
3. You want a specific fruit or leaf character guaranteed. Vegetative propagation is the only way to reproduce a named selection exactly.

So the sequence to follow is: plant, let the tree prove itself for a few seasons, and graft only if it disappoints. It bears fruit in 2–4 years, so you should not have to wait long for the verdict.

Climate, hardiness and where it will grow

Cherry plum suits temperate, Mediterranean and subtropical climates and grows in hardiness zones 4–10. Zone 4 corresponds to winter lows of about −34 °C (−30 °F), so cold hardiness is rarely the problem — the tree is tough at the cold end of its range. The constraint sits at the warm end, where zone 10 winters simply do not accumulate enough chilling for dependable cropping. In that band, treat the tree as an ornamental first and any fruit as a bonus.

Planting

You can plant in winter, spring or summer, which gives useful flexibility — in cold regions plant into the growing season, in hot ones plant in the cool months so the roots establish before summer stress arrives. Choose a position in full sun or half shade; full sun gives the strongest flowering and the best-coloured foliage on purple forms, while half shade is tolerated and sometimes preferable in very hot climates.

Give the tree room. Cherry plum reaches 3–14 m (10–45 ft) depending on the form and how you manage it, and it is a medium to fast grower, so a sapling that looks lost against a wall will not stay that way. Watering is straightforward: an average amount of water, applied steadily rather than in extremes. Erratic watering during fruit development is the usual cause of undersized or splitting stone fruit.

Thinning the bloom in the early years

In the first years of cropping it pays to thin the bloom. A young tree allowed to carry every flower it sets diverts energy into a heavy crop of small fruit instead of into trunk, roots and framework branches, and it often responds by cropping poorly the following year. Removing a proportion of the flowers gives you larger fruit now and a stronger tree later.

Pruning

Prune in winter, when the tree is bare and the structure is easy to read. Cherry plum does not need aggressive shaping; the priority is a clean, open framework:

• Dead wood — remove it entirely. Dead branches are the entry point for the borers and diseases this tree is prone to.
• Weak and thin branches — whippy growth that will never carry fruit, and that shades the interior for no return.
• Infected wood — cut out any branch showing disease, back into clean tissue, and take the prunings away from the tree rather than leaving them on the ground.

The reason to be diligent about the last two points is airflow and inoculum. A congested canopy stays damp longer after rain and gives fungal problems a foothold, and infected wood left in place simply re-infects the tree next spring.

Pests, disease and the winter clean-up

Be honest about this tree’s weak point: cherry plum is very sensitive to pests and disease. The regulars are:

• Aphids — clustering on soft new shoots and the undersides of young leaves, curling and distorting growth and leaving sticky honeydew that sooty mould then colonises. Deal with them while the infestation is on a few shoot tips.
• Borers — larvae tunnelling under the bark, usually entering through wounds, sunburnt bark or dead stubs. They are far easier to prevent than to cure, which is why clean pruning cuts and prompt removal of dead wood matter.
• Mites — feeding on leaves and producing fine stippling and bronzing, worst in hot, dry, dusty conditions.

The autumn sanitation routine

If the tree has been attacked, do the clean-up at the beginning of winter and do it properly:

1. Collect every fallen leaf from under the tree.
2. Collect every dropped fruit from the ground, including mummified and rotten ones.
3. Cut out all infected branches.
4. Dispose of the lot away from the tree — do not compost it at the foot of the trunk.

This is not tidiness for its own sake. Fallen leaves and abandoned fruit are exactly where fungal spores and fruit fly overwinter, sitting a metre below the branches they will re-infest in spring. Clearing them in early winter breaks the cycle before it restarts, and it is the highest-value hour you will spend on this tree all year.

Protecting the fruit from birds and fruit fly

The crop itself has two dedicated enemies: birds and fruit fly. Both need to be dealt with before the fruit colours up, not after.

• Netting is the reliable answer for birds. Cover the tree as the fruit begins to ripen and make sure the net is held away from the branches — birds will simply pick through netting that rests on the fruit.
• Traps are the practical tool against fruit fly. Set them out early so you catch the first arrivals rather than the second generation; by the time you see stung, weeping fruit, the larvae are already inside.
• The autumn ground clean-up above is also fruit-fly control — infested fallen fruit is the nursery for next year’s population.

Harvest and what to do with a big crop

Cherry plums are pollinated by bees after the spring bloom and ripen in summer. The fruit is small — 1–3 cm, purple, with a small stone — and a mature tree can produce a great many of them over a short window, which is why cherry plum is more often processed than eaten one at a time. Proven uses for a glut:

• Eaten fresh, straight from the tree at full colour.
• Jam — the classic destination. Cherry plums are naturally high in acid and pectin, which is why they set well.
• Juice.
• Alcohol — fermented or steeped into liqueurs and spirits.
• Cakes and baking — the sharpness holds up against sugar and pastry better than a dessert plum does.

Because the stones are small relative to the fruit, cooking down and sieving is usually quicker than pitting by hand.

Growing cherry plum in a container

Cherry plum is not a houseplant — it is deciduous, it needs winter cold to fruit, and it will not thrive indoors. It can, however, be grown outdoors in a planter or large container. Treat the pot as a way of restricting size: the tree will stay far below its potential 3–14 m, but you take on the watering. Container soil dries fast and cherry plum wants steady, average moisture, so check it often through fruit development and keep the drainage genuinely free. Everything else — full sun, winter pruning, the autumn clean-up — applies unchanged.

Starting cherry plum from seed

You can raise cherry plum from seed, and it is the cheapest way to get a tree, provided you accept the trade-off: a seedling is not a copy of its parent. It may come up green-leaved rather than purple, and there is no promise about the size, colour or quality of the fruit. That is not a reason to avoid seed — seedlings make perfectly good, vigorous trees and excellent rootstock — but it is a reason to keep grafting in reserve. If the fruit turns out not to be what you wanted, graft a scion from a tree whose fruit you have actually tasted onto the seedling you have already grown.

For the full plant profile see our Cherry plum growing page.