How to grow and prune hibiscus
For tropical appeal with flower colours that don’t just pop, they scream “Wow!”, there is only one choice: the Hawaiian hibiscus.
What you need to know about hibiscus
Name: hibiscus, Hawaiian hibiscus (Hibiscus rosa-sinensis cvrs)
Plant type: evergreen shrub
Foliage: large, shiny, dark green leaves, up to 15cm. Oval-shaped but variable, often with ragged “teeth” on the edges.
Climate: tropical and sub-tropical, warm temperate and sheltered areas of cool temperate.
Soil: rich, well-drained, improved soil.
Position: sunny, wind protected. Some varieties tolerate minor frost.
Flowering: large, distinctive colourful flowers from early summer through until winter.
Feeding: heavy feeders. Controlled-release fertiliser, supplemented with comported manures.
Watering: must have regular, reliable water over the hot months.
Appearance and characteristics of hibiscus
You’d be hard pushed to find flowers more flamboyant than those of the Hawaiian hibiscus. They’re instantly recognisable, with their wide-open trumpet-like flowers and pronounced stamen—and that colour range! You’ll find just about every imaginable colour available, even striped forms, and they can be as large as 15cm across. Combine these knockout warm-season flowers with lush, deep green foliage and you’ve got a plant that’s a must-have for any tropical-look or resort-style garden.
Hibiscus is an evergreen shrub, sometimes a small tree, of variable size. Although some can heights reach over 3m, they are rarely seen much taller than around 1.5m, as a well-cared-for plant will be heavily pruned annually. Typically, hibiscus has a vase-like form with a short, stout trunk.
Although often described as a summer-flowering shrub, it flowers mainly in spring and then again in autumn, with spot-flowering in between. There are some more recently developed varieties that will flower across the warmer months.
Select your hibiscus when it is in flower to make sure the colour suits your needs. Check that the variety you select is a suitable size and is tolerant of your particular conditions, especially if you’re in a cooler region.
Uses of hibiscus
Hibiscus can be used in many ways, including:
as a great addition to tropical and resort-style gardens
the perfect plant for near the pool
to add some serious flowering colour
to celebrate its lush foliage, which means the plant looks excellent even when not in flower
pruned into a hedge
for smaller varieties, as an excellent potted plant.
How to plant and grow hibiscus
For the best flowers, plant your hibiscus in full sun in a warm position, ensuring protection from strong or damaging winds. Your hibiscus will need good-quality, free-draining soil with added composts and manures. It must have reliable water across the hotter months, or during dry periods.
If your area is prone to frost, ask the plant specialist in your local garden centre to suggest a suitable variety.
Improve soil at planting time by blending through quality compost or composted manure, and add a controlled-release fertiliser when planting. Stake larger plants if required, then mulch well with a product such as lucerne or pea straw, making sure the mulch is not pushed against the trunk—leave around 5cm clear.
Caring for hibiscus
Follow these tips to ensure your hibiscus is happy and healthy:
Reliable water during hot, dry weather is critical for flowering performance.
Hibiscus responds well to fertilisers that are balanced for citrus.
Keep your hibiscus well-mulched, especially during warmer weather.
Before applying mulch, spread controlled-release fertiliser and composted cow manure.
Bushes can be side-dressed with composted cow manure after the main pruning, in early spring and late summer
How and when to prune hibiscus
Hibiscus pruning requirements vary by variety, so keep the original label. Aim to remove any dead or diseased wood, and to trim back last season’s growth, shaping the bush as you go.
The major annual pruning is conducted in late September. Vigorous shoots will appear in October and November. Tip-prune these lightly to increase bushiness. This will increase flower numbers, too. Also consider a light prune in February to tidy the bush and bring on more flowers.
Diseases and pests
Watch for the following pests when growing hibiscus:
Aphids may feed on new leaf or flower shoots.
Leaves may be chewed by caterpillars or grasshoppers.
Flower buds dropping before they open can be a sign of hibiscus beetle. It feeds on young flowers, and this causes the bush to drop them.
Growing hibiscus from cuttings
You can take semi-hardwood cuttings of around 6cm in length in summer through until autumn. In winter, save 10cm-long hardwood cuttings from your pruning offcuts. Cuttings should be dipped in propagating gel, placed in a suitable propagating mix and kept moist in a warm spot.
If you like this then try
Bougainvillea: if you’re looking for a plant with vibrant colours to bring a tropical look to your garden, then you can’t go past bougainvillea.
Frangipani: hibiscus and frangipani are the perfect tropical-look partners.
Palm tree: add some height and serious resort-style character to your garden with a palm.
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