Hibiscus

Hibiscus

A group of attractive, free-flowering, hardy and tender shrubs. A few species are hardy enough for UK gardens and many of the less-hardy species make excellent houseplants or greenhouse specimens. Hardy forms produce an abundance of colourful showy flowers in late summer, when many other plants are fading.

Family: Malvaceae (Mallow family)
Botanical Name: Hibiscus
Common Names: Tree Hollyhock, shrubby mallow, Rose of Sharon

Foliage: Evergreen or deciduous. Mid-green, ovate or palmately lobed leaves. Leaves appear in late spring.

Flowers: Large distinctive, flared saucer or funnel shaped flowers in shades of blue, pink, red, purple and white. Single, double or semi-double forms are available.

Flowering Period: Late summer into autumn.

Soil: Moist but well-drained, reasonably fertile, soil (chalk, clay, sand or loam). Alkaline or neutral pH.

Conditions: Needs full sun to flower well. Best grown in a south or west-facing aspect, in a sheltered location.

Habit: Upright, bushy.

Type: Medium sized shrub or small tree.

Origin: Tropics and subtropics, Asia, India, China

Hardiness: Hardy or tender, depending on species. The hardy forms are frost tolerant down to about -15°C.

Planting and Growing Hardy Hibiscus

The hardy hibiscus varieties can bring a taste of the exotic to your garden. Plant out from autumn to late spring.

Grow in a sheltered sunny position in any good, well drained, humus-rich soil, that is not acidic. Note: they are often slow to establish, providing very little growth in first few years.

Hardy forms are ideal as specimen shrubs or mixed in with other plants in the shrubbery or mixed border. Protect from cold winds. Ideally under the protection of a south or west facing wall.

For greenhouse or houseplant specimens use an open fibrous compost of rich fine loam and sand. These tender forms can also be grown in large pots and sited on a sunny patio in summer. However, be sure to bring them back in around September, before any chance of frost.

Taking Care of Hibiscus

Water thoroughly during dry weather until well established. Mulch with organic matter in spring and apply a general fertilizer suitable for shrubs.

Remove faded blooms after flowering.

Pruning Hibiscus

Pruning is not normally necessary. Can be trimmed in late winter or early spring to remove dead and damaged wood, or to shape or restrict growth.

Pests and Diseases

Aphids may attack new growth. Can be affected by powdery mildew.

Propagating Hibiscus

Take semi-ripe hardwood cuttings of hardy forms in July, about 4in (10cm) long, and root in a greenhouse or cold frame.

Sow annuals in spring where they are to flower. Note: annuals often readily self-seed.

Tender species can be grown from seed sown in gentle heat in spring or by cuttings taken in early spring and rooted in a heated propagator.

Popular Varieties of Hibiscus

The main hardy garden form, H. syriacus, is useful free flowering garden shrub, eventually growing to 10ft (3m) or more. Available in a wide range of colours, with both single and double flowered varieties. The flowers are not as flamboyant as the tropical species, H. rosa-sinensis, but these are mainly are frost tender and can only be grown in the conservatory or heated greenhouse.

Hibiscus trionum (flower-of-an-hour) is a hardy annual with striking creamy-white flowers with dark centres that open in the morning. Height to 30in (75cm).

Hibiscus syriacus is the main hardy shrubby garden species. Height 10ft (3m), spread to 6ft (1.8m). Good cultivars include:

'Admiral Dewey' is a vigorous, deciduous form with green, lobed leaves and large pure white double flowers. Available at Gardening Express.

'Ardens' is a beautiful shrub with double purple flowers from July to October. Available at Gardening Express.

'Azurri' (Belli Colori Azurri) bears gorgeous, lilac-blue flowers, each with a contrasting maroon centre, from late summer through to October. Available at Van Meuwen. Available at Thompson & Morgan.

'Blue Bird' violet-blue flowers with a reddish centre. Available at Gardening Express.

'Blue Chiffon' has large double blue flowers. Available at Gardening Express. Available at Thompson & Morgan.

'China Chiffon' has large ruffled white double blooms. Available at Gardening Express.

'Diana' large single white flowers.

'Dorothy Crane' white with a crimson eye.

'Duc De Brabant' double magenta flowers. Available at Gardening Express.

'Hamabo' striking pale pink flowers with a crimson eye. Available at You Garden. Available at Thompson & Morgan.

'Kakapo' is a medium-sized upright shrub with double pink flowers from July to October. Available at Thompson & Morgan.

'Lady Stanley' (Elegantissimus) double white flowers with a maroon centre. Available at You Garden. Available at Thompson & Morgan.

'Oiseau Bleu' has large lavender-blue flowers, with maroon and cream centres, from August until October. Awarded an RHS AGM. Available at Van Meuwen. Available at Thompson & Morgan.

'Purple Ruffles' produces an abundance of large double (or even triple) ruffled flowers in mid to late summer. Dark green foliage. Available at Van Meuwen. Available at Thompson & Morgan.

'Red heart' white with a crimson flower centres. Available at Gardening Express. Available at Thompson & Morgan.

'Tivoli' has deep green foliage and large bicoloured flowers. Available at Gardening Express.

'White Pillar' has ice white, semi double blooms that contrast well with the lobed, bright green foliage. Available at Van Meuwen.

'William R. Smith' pure white flowers with a frilly edge.

'Woodbridge' single crimson-pink flowers with a carmine centre. Available at Gardening Express. Available at Thompson & Morgan.

Hibiscus Chiffon Mosaic is a unique form with charming tri-coloured ruffled double flowers that contrast beautifully with the shiny leaves. Suitable for smaller gardens or patio planters. Height to 5ft (1.5m). Available at Gardening Express.

Hibiscus Gandini Santiago PURPLE PILLAR (new cultivar) grows in a natural columnar shape with gorgeous semi-double purple-violet flowers. Height to 10ft (3m) or more, spread to 3ft (1m). Useful in smaller gardens. Available at Gardening Express. Available at Van Meuwen.

Hibiscus moscheutos Carousel 'Jolly Heart' is a colourful shrubby perennial with large white flowers each with a dark pink coloured centre that contrasts well with the deep burgundy-purple foliage. Available at Gardening Express.