For a smallish shrub of fairly delicate habit, hibiscus sure can produce the most enormous, flamboyant flowers.
They are tough, too. Even a neglected hibiscus bush can continue to flower through the harshest conditions. In the tropics, hibiscus can flower throughout the year — including winter.
Choice of flower colour is endless, with the exception of a true blue. Hibiscus come in shades of yellow, orange, red, pink, mauve, white and every colour in between. Mottled or multi-coloured hibiscus are also an interesting option.
Most nurseries stock grafted hibiscus as well as cutting-grown plants. Many of the really special hibiscus (modern hybrids) will perform better when grafted onto a more hardy root stock. You will pay more for grafted plants due to the labour involved in the process, but the results are worth the investment. Cutting- grown hibiscus will usually be of the older varieties and there are some beautiful varieties available.
Where to plant hibiscus
Consider that over two years, most hibiscus will grow to 1.5–2 metres high. Be sure they always receive optimal sunlight. Full sun for the whole day will see your hibiscus grow and flower to its full potential. Hibiscus plants in any level of shade will tend to be leggy and will not flower well.
Hibiscus plants can be grown in large pots or tubs, but remember that they will depend on you for all their water and nutritional needs. Repotting is advisable at least every two years. Ceramic or terracotta pots are preferable, but not essential. Plastic pots sitting in the sun can tend to overheat the root system, which in time can lead to health problems. Use a reliable potting mix such as Searles Premium Potting Mix. Potted hibiscus should be watered about every 2–3 days, if not every day.
Hibiscus plants in the garden will tolerate relatively dry conditions, once established. A good soaking every week will ensure good growth and flowering and a thick layer of mulch will help the soil retain moisture. Do not allow the mulch to touch the stem of the plant.
Many gardeners are intimidated by the idea of pruning, but pruning is essential if you want healthy-looking bushes and vigorous flowering. First, prune out any diseased or dead branches from the centre, as well as crossed-over branches. This will reduce competition and also allow sunlight and airflow to those new shoots waiting to grow. Of the outer branches, reduce last season’s growth by at least one third. Always cut just above a bud that is facing outward, as the new branch will grow in whichever direction this new bud is facing. You may be alarmed at the appearance of your hibiscus immediately after pruning — but don’t panic. Very soon, your hibiscus will bounce back with more gusto than ever.
Apply SeaMax Fish & Kelp to the foliage weekly or fortnightly to greatly enhance plant health. Apply a small amount of Searles Hibiscus & Bougainvillea Food on a regular basis (every 3–4 weeks) to induce bursts of growth. In the tropics, hibiscus are growing and flowering throughout the year so fertiliser should be applied in smaller amounts on a more regular basis for continual feeding. If your plant doesn’t seem to be responding to the fertiliser, check the pH of the soil which should be between 6.2 and 6.5.
If you want really big, profuse and colourful flowers, use a liquid fertiliser that is high in potash or potassium, such as Searles Liquid Potash or Searles Flourish®. Follow these tips and your hibiscus will flower their heads off!
Hibiscus pest control
Keep your hibiscus plants healthy and well nourished and pests should be little problem. The worst pest of the hibiscus is the hibiscus flower beetle, which feeds on the unopened and developing flower bud. Healthy plants will detect the hibiscus beetle and drop the damaged flower bud, so if you notice flowers falling prematurely it can usually be taken as a sign of the beetle’s presence. From time to time you may also find grasshoppers, aphids or caterpillars. Control hibiscus flower beetle and aphids with Searles Conguard spray. Simply keeping an eye on your plants will go a long way in preventing pest outbreaks.