Strawberry tree

Family

Ericaceae

Habit

Tree

Height

7 m

Spread

8 m

Growth

medium

Lifespan

100 years

First yield

after 4 years

Yield per plant

up to 20 kg a year

Yield in cultivation

up to 4 t/ha

Energy yield

100 kcal per m² a year

Hardiness

zone 8–11

Shade tolerance

partial shade

Soil

Sand, Silt, Loam

Soil moisture

very dry – moist

pH

5.5 – 7.5

Synonyms

Medronho, Madrone,

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: The fruits of the strawberry tree are spherical, about two centimetres across, scarlet and covered in a warty, rough surface that gives the tree its name. They need some twelve months from flower to ripeness, which is why the tree flowers in late autumn while still carrying the previous year's fruit — a sight few other woody plants offer. Harvest runs from October to December, and only fully ripe: unripe fruits are hard and astringent, ripe ones soft, mealy-sweet and mild to almost flavourless. The species name unedo, "I eat only one", alludes to exactly that. Its vitamin C content is remarkable at around 250 milligrams per hundred grams, alongside plenty of carbohydrate and fibre. The fruit is made into jam, fruit jelly and liqueur; in Portugal the fermented fruit is distilled into the spirit medronho. Overripe fruit ferments on the tree and then holds small amounts of alcohol.

Medicinal: The strawberry tree is underutilized in herbal medicine and requires further modern research. All parts of the plant contain Ethylgallate, a substance with potent antibiotic effects against Mycobacterium bacteria. The leaves, bark, and roots have astringent and diuretic properties. They also act as antiseptics on the kidneys, making them beneficial in treating urinary tract conditions such as cystitis and urethritis. Their astringent properties are useful in managing diarrhea and dysentery, and like many other astringent plants, they can be used to make a gargle for treating sore throats and irritations. Leaves are harvested in summer and dried for later use. The flowers have mild diaphoretic effects.

Other uses: Bark, leaves and fruit of the strawberry tree are rich in tannins and were long used around the Mediterranean for tanning leather. Its wood is hard, firm, fine-grained and elastic and is used for turnery, tool handles, bows and flutes; as firewood and for charcoal it mattered regionally. Evergreen, salt-tolerant and able to reshoot after fire, it suits Mediterranean hedging, coastal shelter planting and the reforestation of eroded slopes. The honey is a speciality of its own: because the strawberry tree flowers in late autumn when hardly any other forage is available, its nectar yields a single-source, pronouncedly bitter honey — the Sardinian miele amaro, rare and correspondingly sought after. Here it is above all an ornamental, carrying flowers and red fruit together through the winter.

Site: In Central Europe the frost question decides everything else. The strawberry tree is not reliably hardy even in vine-growing climates, so the safe option is container culture with bright, cool, frost-free winter quarters; planted out it needs a sheltered south wall and winter protection. Its summer position should be sunny to lightly shaded, and above all warm and sheltered from wind, on free-draining soil. Unlike most of the heather family it tolerates lime, and reacts badly only to waterlogging and compacted ground. Drought, salt spray and air pollution it takes in stride — which is why it is a common street and courtyard tree around the Mediterranean. One thing to weigh: the scarlet fruits drop in winter, squash underfoot and stain paving, terraces and timber decking; above seating and paths that is a nuisance. At five to seven, rarely ten metres, its growth stays manageable. Care: Winter quarters should be bright and cool, around five to ten degrees; plants overwintered dark and warm drop their leaves and make drawn growth. Water sparingly through winter too, but never let the rootball dry out completely. The strawberry tree takes pruning well: it reshoots reliably from old wood and even from the rootstock, so hard renewal cuts are possible; prune after harvest in late winter, before growth restarts. Feed sparingly from April to August with a low-lime fertiliser. The plant goes outdoors after mid-May. Because flowering and fruit ripening fall in the same period, the tree carries flowers and fruit at once in its winter quarters — but pollination fails there for want of insects, so container plants usually set little.

Sowing is the usual route. Seed is washed out of fully ripe, soft fruit, since adhering pulp inhibits germination, and then cold-moist stratified for about six to eight weeks. Sow shallowly into a free-draining, not overly rich substrate; germination is uneven and spread over several weeks at 15 to 20 degrees. Seedlings grow slowly at first and are better kept frost-free for their first two winters. True-to-type propagation works from semi-ripe tip cuttings in late summer, rooted under film or mist with bottom heat; success is variable and improves with rooting hormone. Because the plant resprouts readily from the stool, layering is also an option.

The strawberry tree flowers from October to December, at a time when little else in its home range offers nectar — for late-flying bumblebees and honeybees this is a significant late forage, and the source of the tangy strawberry-tree honey of the Mediterranean. The flowers are protogynous and are pollinated mainly by bumblebees. As larval food the species is almost irrelevant in Central Europe: one moth species and two wild bee species are recorded. The red fruits ripen a full year after flowering and are dispersed by magpies and jays. The dense evergreen foliage provides cover and nesting opportunities year-round — in a Central European garden the real contribution of this introduced species.

Besonderheiten: toleriert Wind, Salz, Dürre, Feuer, aber kein Umpflanzen; sein Anbaupotential ist noch nicht ausreichend erforscht, die 45kg/ha sind Wildsammlung, die t/ha hochgerechnet für eine Plantage, die es so noch nicht gibt; Nährwertangaben und Geschmack variieren je nach Standort (Boden/ Klima) & von Strauch zu Strauch; pharmakologischer Schatz;

Western Mediterranean and Atlantic western Europe: Portugal, Spain, southern France, Italy, the Balkan peninsula and north-west Africa. The strawberry tree is a characteristic species of evergreen sclerophyll vegetation, reaching about 600 metres in the Cévennes and 1,500 metres in the Moroccan Atlas. Large continuous stands occur in the Serra de Tramuntana on Mallorca. Far detached from the main range lies the Irish population near Killarney, a relict of the so-called Lusitanian flora. The species does not occur wild in Central Europe; it has been kept here since the nineteenth century as a container and conservatory plant and is planted out only in the mildest wine-growing districts.

The strawberry tree is a character species of the evergreen sclerophyll vegetation of the Mediterranean — the maquis and its transitions into open holm oak and cork oak woodland. It occupies stony, often shallow slopes and rocky coasts and grows on acid as much as on calcareous soils, which makes it an exception among the heather family. Its yearly rhythm is cut to the Mediterranean climate: it survives high-summer drought through leathery evergreen leaves and deep roots, and flowers only in late autumn as the rains set in. Fire belongs to sclerophyll vegetation too — after burns it reshoots vigorously from the rootstock and is among the first species to reclaim the burnt ground. In the Cévennes it climbs to about 600 metres, in the Moroccan Atlas to 1,500.