Hibiscus – Hibiscus rosa-sinensis

Hibiscus rosa-sinensis comes from tropical Asia and flourishes in warm conditions. This evergreen shrub has stems that become woody after a year or two. It has attractive oval and glossy leaves.

The flowers appear from late spring through the summer. They are in shades of white, pink, red, yellow, buff or orange. They last for 1-3 days and are usually large–about 8-13cm (3-5in) across. Some flowers are single, some semi-double with more than one layer of petals — and others are fully double.

Many kinds of hibiscus are so tender that they can only be grown in warm greenhouses, but Hibiscus syriacus is hardy in all but the coldest parts of Britain, and is a handsome deciduous shrub which can reach loft, but is more usually about 6 ft., with showy, mallow-type flowers in late summer and early autumn. It likes a warm sunny place, will thrive in all reasonably fertile, well-drained soils, including those containing chalk or limestone, and can be pruned in late winter if it grows too large. It transplants badly so should be purchased in containers while still small and plants should also be staked securely for the first few years to prevent roots being damaged by wind rocking.

Size and growth

You can buy hibiscus plants of different sizes. The usual height at which they are sold is from 15– 30cm (6-12in). They are vigorous growers and can grow to 1.5m (5ft) if they are not cut back. Prune them annually.

Growth all year

If you have the space you may prefer to keep your hibiscus growing all year, rather than let it have a dormant period. If so, give it regular misting, watering, feeding and as much light as possible. It could reward you with flowers through most of the winter and grow to become a large plant.

Display ideasHibiscus - Hibiscus rosa-sinensis

Set this plant in a bright floral china pot matching the colour of its flowers.

Care Through The Year

February–March

If you have space and want a large shrub, transplant hibiscus into a larger pot. Use a soil-based potting mixture. Gradually increase amount of water, but keep in a cool spot around 12°C (54°F).

March–April

Raise the temperature to between 20-24°C (68-75°F). Water frequently and add liquid fertilizer every 3-4 weeks.

May to October

Avoid dry air by misting often and maintaining a constant temperature. Add liquid fertilizer with each watering. Remove withered blooms and cut back leggy growth.

November

Reduce water and fertilizer gradually. Lower the temperature so that the plant prepares for its winter

rest. (You may wish to keep it growing instead.) Ensure it has as much light as possible.

December–January

The winter months are the time when the plant will rest. Ideally your hibiscus should be in a position where the temperature range is 10°-15°C (50°-60°F).

Plant Problems

  • Leaves uneven and curling and lack of growth are caused by aphid attack.
  • Prevention: Check for aphids at tips of shoots and on buds every time you water. Combat with a suitable insecticide.
  • Red spider mites may attack if the room is warm and the air is dry. Prevention: Mist fre- quently to discourage them and if attack is serious use a suitable insecticide.
  • Yellow leaves are caused by lack of water or root damage. Although unlikely, this could also be a result of over-feeding. Prevention: Water more frequently and dilute the fertilizer.
  • Bud-drop is due to lack of sufficient light, drying out or extremes in day and night temperatures.
  • Prevention: Water regularly, place in a light position and regulate the temperature.

GENERAL CARE

Needs care. It can be rested in winter to prevent it from getting too big. To improve its shape, cut it back in March.

Potting: Use a soil-based potting mixture and transplant or repot in March. You can use tipshoots to propagate new plants. Use a rooting mixture of equal parts of peat and coarse sand.

WATERING

Water regularly and generously in the growing season and mist during the day. Gradually reduce amount and frequency of watering as plant enters its dormant period.

Feeding: Feed with a liquid fertilizer at half strength during period of active growth. Stop feeding during dormancy.

CONDITIONS

Light: It needs sunlight, especially during the growing season. Give it good light in winter too, through dormancy.

Temperature: It prefers temperatures above 18°C (65°F) during the growing season. Winter temperatures need to be between 100-15°C (50°— 60°F) for dormancy.

When to buy

Hibiscus are usually available from garden centres from early spring to early autumn — and flower between May and September.

What to look for

Check that your plant has lots of new buds, healthy leaves and looks robust. Reject plants with any signs of aphid or red spider mite infestations.

Lifespan

Although it is often treated as a short-lived plant, hibiscus can grow on for years.

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