Mirabelle plum

Family

Rosaceae

Habit

Tree

Height

10 m

Spread

6 m

Growth

medium

Lifespan

50 years

First yield

after 4 years

Hardiness

zone 5–9

Shade tolerance

light shade

Soil

Sand, Silt

Soil moisture

dry – very moist

pH

6.5 – 8

Edible: The mirabelle is the sweetest of the European plums: small, round, waxy yellow, often dotted with red, two to three centimetres across, high in sugar and low in acid. The flesh parts readily from the stone, which makes it unbeatable in the kitchen — stoning happens almost in passing. Straight from the tree it keeps only days before turning mealy, so most of the crop goes into processing: tarts and cakes, jam with its characteristic yellow, compote, chutney and above all brandy. Lorraine mirabelle eau-de-vie is its best-known use of all. Dried, it gives a firm, honeyed fruit. As in all stone fruit the kernels contain amygdalin and are not processed with the flesh.

Other uses: Beyond its fruit the mirabelle is useful above all as a tree. In a traditional orchard it fills the gap between the early flowering of blackthorn and cherry and the late flowering of apple and pear, yet with a crown five to six metres across it stays well below a standard apple and so fits medium-sized gardens. Its wood is hard, fine-grained and reddish; in small quantities it is turned, in larger ones used for smoking and firewood. The freely produced root suckers can be lifted for rootstocks or left to close gaps in a field hedge. As a house tree it has the practical merit that the crop ripens in stages over two to three weeks rather than all on one weekend.

Site: The blossom comes in April and is exposed to late frost — hollows and frost pockets cost the whole crop with some regularity, so a slightly raised, airy position is the most important decision you make. Keep your distance from existing plum and damson stands if sharka has appeared there: the virus is carried by aphids and cannot be treated. The tree throws up plentiful root suckers, which become permanent work in lawn and beds but cause no trouble at a hedge edge or in rough grass. Ripe fruit drops and draws wasps — a bad idea above a terrace, seating area or path, and equally bad where people walk barefoot. Allow room: five to six metres for a half-standard, three to four for a bush. Care: Prune after harvest in late summer, not in winter — open wounds on stone fruit are entry points for brown rot and gummosis in the cold, damp half of the year. Keep the crown open and airy, which is the most effective prevention against fruit rot. If shoot tips suddenly wilt in spring with the dead flowers still attached, that is blossom wilt: cut the affected shoots well back into sound wood and remove them, and take the mummified fruit off the tree rather than leaving it. Feed nitrogen sparingly, since too much drives soft growth and draws aphids. Young trees need a stake, a vole basket and protection against hares and deer. Thin a heavy set, otherwise branches break and the tree falls into biennial bearing. Against the plum moth, clearing fallen fruit and pheromone traps are what help.

Mirabelles grown from stones do not come true — they give usable but unpredictable seedlings and serve mainly as rootstocks. True-to-type trees come from grafting: chip or shield budding with a dormant bud in July and August, or whip-and-tongue grafting in spring, worked onto St Julien A for moderate vigour, Wangenheim damson for weaker growth or plum seedlings for vigorous standards. The rootstock governs final size, stability and the start of cropping more strongly than the cultivar does. A third route is root suckers: own-rooted trees — that is, ungrafted ones growing on their own roots — throw suckers that are true to type and can be severed with a spade in winter and moved. On grafted trees, by contrast, the suckers belong to the rootstock and do not carry the wanted cultivar.

With its plum relatives the mirabelle ranks among the strongest insect trees in the garden. Its flowering in early to mid April falls exactly when female wild bees are provisioning their first cells: nectar and pollen are both abundant, and forty-six wild bee species are recorded on Prunus domestica, along with twelve hoverfly and seven beetle species. As caterpillar food it carries sixty-five butterfly and moth species, five of them specialists. Thirty-one bird species use the tree, partly for the fallen fruit, partly for the insects in bark and crown; the dense crown of older mirabelles is regularly taken for nesting, and sucker thickets at a hedge edge give ground cover. In August and September the windfalls are an important food source for wasps, hornets, butterflies such as the red admiral, and at night for hedgehogs and edible dormice — good reason to leave some of it lying.

Special characteristics: mostly self-fertile can stand alone, a pollinator raises the yield; ripens late July-September by cultivar harvest staggered over 2-3 weeks; freestone flesh quick stoning; tends to overset+biennial bearing thin the crop; strong root suckers true-to-type propagation on own-rooted trees, rootstock growth on grafted ones; prune in late summer only (brown rot+gummosis); main growing region Lorraine, ~70% of the world crop;

Asia Minor and northern Persia as its origin, Lorraine as its centre. The mirabelle is a subspecies of the cultivated plum and reached western Europe by way of the Mediterranean, where it has been recorded since the fifteenth century. Its centre of gravity remains Lorraine: some 250,000 mirabelle trees stand there and the region brings in around seventy per cent of the world crop — the Mirabelle de Nancy and Mirabelle de Metz are named after it. In Germany, Austria and Switzerland it is spread through traditional orchards, gardens and field margins, concentrated in the warmer wine-growing districts of the Rhineland-Palatinate, Baden and the Burgenland. Being a purely cultivated plant, it has no natural range.

As a cultivated form the mirabelle has no natural site of its own. Its parent species — blackthorn and cherry plum — come from hedges, woodland margins and scrub of the warmer lowlands, and that is where the mirabelle turns up too: on field margins, banks and in old orchards, where it escapes by root suckers and stone-grown seedlings and persists for decades. It asks for a warm, airy position with deep soil free of waterlogging and takes calcareous ground well. What matters is less the winter hardiness of the wood, which reaches below minus twenty degrees, than the risk of late frost at flowering time in April — hollows where cold air collects cost the whole crop with some regularity.