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Hibiscus  

Hibiscus (Hibicus rosa sinensis) are shrubs widely grown in Australian gardens for their flamboyant late spring to autumn flowers in colours of red, pink, orange, yellow, purple and white or in colourful combinations.

New flowers, which may be double or single, unfurl daily. These deciduous shrubs can be grown as a stand-alone feature plant, as an informal hedge, or as a container or courtyard plant. They are also suited to planting around a swimming pool.

There are many named varieties in sizes that range from under 1m to well over 3m in height. See a wide range of hibiscus varieties on show at summer flower garden shows or visit your hardware or garden centres for great advice on a variety to suit your garden. Here are a few to consider:

  • Hibiscus syriacus This species flowers from spring to autumn in shades of white, mauve, pink or lavender. This variety will grow 3-6m high by 2-3m wide. It is also cold tolerant.
  • Hibiscus tiliaceus This species flowers in the warmer months in shades of white or yellow. This variety grows to a large shrub (8m x 3-6m) so ensure you have the space in the garden. Ideal as a windbreak, it will also tolerate coastal conditions.
  • Hibiscus moscheutos This species flowers from summer to autumn, in shades for white, pink or red. This smaller variety growing to 2.4 m high by 1mn it is ideal for borders or containers.
  • Hibiscus schizopetalus The species flowers from spring to autumn, in shades of red, white or pink.  The Japanese lantern style flowers are very bird attracting.

Growing conditions

Aspect Hibiscus thrive in full sun positions but prefer shelter from strong winds. Even though they are winter deciduous, they need frost protection.

Soil All grow best in a rich, well-drained soil so dig in added organic matter and/or add in Seasol Super Compost to prepare for planting.

Climate Hibiscus grow in most area except the very cold climates as they are not frost tolerant. In areas with hot summers but cold winters, grow hibiscus in large containers and move them into a sunny, frost-free position during winter.

Successful Hibiscus with Seasol
Seasol helps stressed hibiscus

General care

Watering Established hibiscus plants are drought hardy but all grow and flower best with regular water. Water regularly if plants are in hot, dry or exposed conditions or if they are growing in containers. Apply Seasol or Seasol GOLD when transplanting and throughout the year to aid healthy growth.

Feeding and mulching Hibiscus are big feeders (often called ‘gross’ feeders). Feed throughout the growing season with a fertiliser for flowering plants such as Seasol plus Nutrients Roses & Flowers. Supplement this with a liquid fertiliser such as PowerFeed PRO SERIES for Roses & Flowers . Spread organic mulch enriched with well-rotted cow manure, compost and/or Seasol Super Compost to keep plants free of competing weeds and top up nutrients.

Pruning Hibiscus bushes are pruned in late winter or early spring before new growth resumes. Regularly remove fallen flowers to reduce pest problems (see Watch for below).

Watch for In subtropical climates, a minute insect called erinose mite attacks foliage. The pest is invisible to the naked eye but distorts the leaves with obvious blistered lumps. Control this pest by pruning off damaged growth and disposing of it in a sealed bag in the rubbish. Spray new growth with EarthCare Enviro Pest Oil insect spray.

As flowers form, hibiscus flower beetle may chew holes in petals to access pollen. They cause flower buds to drop. The beetles are black, 3mm long and very hard, which makes them difficult to squash. Non-chemical control measures to reduce beetle numbers include collecting and disposing of spent flowers (put them in a bag and in the garbage bin) and using a trap under affected plants in the form of a white plastic container filled with water and a few drops of detergent. The white colour appears to attract the beetles that then drown in the water. Feed to encourage new growth and buds.

Black sooty mould on leaves is triggered by aphids that are feeding on new growth or around the base of buds. Control aphids by squashing or use EarthCare Enviro Rose Black Spot & insect spray to control both the insects and the mould.