Rose of Sharon

Family

Malvaceae

Habit

Shrub

Height

3 m

Spread

2 m

Growth

medium

Lifespan

30 years

First yield

after 3 years

Hardiness

zone 6–9

Shade tolerance

partial shade

Soil

Sand, Silt, Loam

Soil moisture

dry – very moist

pH

6 – 7.5

Synonyms

Althaea frutex, Hibiskus, Scharonrose, Syrischer Eibisch, Garteneibisch

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

Edible: Junge Blätter – roh oder gekocht. Sie haben einen sehr milden Geschmack, sind aber etwas bissfest und eignen sich gut für Salate. Aus den Blättern oder Blüten wird Tee zubereitet. Blüten – roh oder gekocht. Sie haben einen milden Geschmack und eine schleimige Konsistenz und sind sowohl optisch als auch geschmacklich eine Bereicherung für Salate. Wurzel – essbar, aber sehr faserig. Schleimig und geschmacksarm.

Medicinal: In traditional Chinese and Korean medicine the bark and root bark are applied externally as a decoction against skin fungi and itching, and the flowers taken internally for diarrhoea. The mucilaginous leaves and flowers were drunk as a tea for irritable coughs. Tradition, without evidence of efficacy.

Other uses: Low quality fiber from the stems is utilized in cordage and paper production. The seed has approximately 25% oil and is potentially edible. Leaves are used to create a hair shampoo. Flowers yield a blue dye. Commonly planted as a hedge in Southern Europe.

Site: Rose of Sharon needs full sun and summer warmth; in shade it simply will not flower. The ideal position keeps the roots in cool, evenly moist soil and the crown in the sun — against a sheltered south or west wall with low underplanting, for instance. It grows upright and narrow, one and a half to three metres tall and rarely more than one and a half wide, so it fits gaps no rounded shrub will take and can be trained into a flowering clipped hedge. Two points belong in the plan: it flowers only from August onwards and is an unremarkable framework before that, so it pairs well with spring flowers at its feet. And the hairy seeds travel far — in warm positions seedlings stand in paving joints and beds the following year. Cut the capsules off before they split if you do not want that; near warm dry grassland and protected sites it should not be planted at all. Its hardiness is limited, to about minus seventeen degrees. Care: Prune in spring, because the flowers form on the current year's wood. Cutting hard back to two to four buds gives fewer but markedly larger flowers; not pruning at all gives many small flowers and a bare base. Patience matters: rose of Sharon breaks bud extremely late, often not until May or June, and is dug up as winter-killed by gardeners every spring. During flowering it needs an even water supply — drought stress makes it drop its buds, which is the commonest trouble with this plant. A mulch layer keeps the soil moist. Give nitrogen sparingly so the wood ripens before winter. Young plants get a cover of leaves and brushwood over the root zone for their first winters. Aphids settle on the buds in early summer and are usually dealt with by ladybirds and hoverflies without help.

Sowing is straightforward: sow the seed in early spring at about twenty degrees and it germinates promptly and evenly. Seedlings flower after three to four years but vary in colour and doubling and mostly revert to the plain violet of the species — named cultivars cannot be kept this way. On the other hand, self-sowing supplies free young plants in warm gardens, usable as rootstock or hedging. For cultivars, propagate from cuttings: semi-ripe shoots in July and August rooted under polythene or mist with bottom heat, or hardwood cuttings in winter in a sheltered outdoor bed. Low branches can be layered. Double-flowered and sterile cultivars such as Diana have no other route anyway, since they set almost no viable seed.

Rose of Sharon is a pollen plant, not a nectar plant. Its large open bowl-shaped flowers yield pollen in quantity, which honeybees and bumblebees collect readily, while almost no nectar is produced — so butterflies and long-tongued wild bees largely come away empty. Its value lies in the timing: it opens from August into October, exactly into the late-summer forage gap when little else in the garden offers pollen. As an introduction from China it has bound no specialised wild bees to itself, and it plays no part as a bird food shrub; the dry seed capsules are hardly touched. What decides its ecological worth is the choice of cultivar: only single-flowered forms are accessible to insects at all. In double cultivars the stamens have been converted into petals, so they supply neither pollen nor nectar and are worthless to wildlife.

Special notes: Breaks bud very late (May/June) - do not write it off as winter-killed; flowers on current-year wood prune in spring; flowering only from August to October, each flower open for one day; drought stress bud drop; only single-flowered cultivars are usable by insects; national flower of South Korea (mugunghwa); the epithet syriacus is an error - origin is China; only moderately hardy (about -17C) cover young plants; heavy self-seeding in warm positions;

East Asia: China. Rose of Sharon is native to the provinces of Anhui, Jiangsu, Zhejiang, Sichuan, Yunnan, Guangdong and Guangxi, and to Taiwan. The epithet syriacus rests on an error: the plant reached Europe in the sixteenth century along Middle Eastern trade routes, so Syria was taken for its homeland. It has been cultivated in Korea for centuries and is the national flower there as mugunghwa; it has a long history in cultivation in Japan and India too. Today it is planted in almost every region with a tropical to temperate climate. In southern Europe and other warm areas it escapes from gardens and counts there as a mildly invasive introduction; in Central Europe it stays largely tied to plantings.

In its Chinese homeland rose of Sharon grows on coastal cliffs, slopes, riverbanks and roadsides up to around 1,200 metres — consistently in open, bright, warm places, never in closed forest. It demands light and summer heat and tolerates moderately moist to seasonally dry soils from sandy to loamy, provided they are nutrient-rich and free-draining. Waterlogging and shade rule it out, as does heavy competition from trees. Its seeds bear hairs and travel on the wind, which makes it a pioneer of disturbed open ground — precisely the trait that lets it escape from gardens in warm regions.