Hibiscus are well suited to Perth's climate and even the most neglected hibiscus will continue to flower every year from spring right through to early winter. Each flower is short-lived, lasting just 1-2 days, but the good news is that numerous new flowers appear daily to brighten up your garden.
Choosing and planting hibiscus
Hibiscus thrive in full-sun positions, they are great for pool surrounds and hedging and are well-suited to pots. Plants grown in the shade will not produce as many flowers and can become straggly and leggy. Keep in mind that hibiscus can easily grow over 2 metres high so space at least a metre apart if using hibiscus as a hedging plant. Prepare the soil with organic matter and a balanced fertiliser before planting. Staking young plants will help to stop them being blown around and damaged in wind. Mulch well after planting, keeping the mulch away from the stem to avoid rot.
Watering and fertilising
Hibiscus are hardy and can tolerate neglect, but for the best blooms keep up with watering in summer and feed monthly with a balanced fertiliser during the flowering period. Be especially mindful of shrubs in pots, which can dry out quickly in the heat.
Pruning and shaping
Hard prune in September, after the coldest weather has passed and the soil starts to warm. Pruning while the weather is too cold can have an adverse effect on the new growth. Cut back by a third to a half, depending on how vigorously your plant grows. Remove old wood, spindly branches and open up the centre of the shrub. Always use clean sharp tools to prune your hibiscus. Fertilise and mulch after pruning.
If your plant is not getting enough sun, or it's too big and causing an obstruction, you can dig it up and transplant it in a new position. Do this in September. Prune by a third, spray with DroughtShield then dig up, getting as much of the roots as you can. Minimise the time it's out of the ground by having the hole ready prepared in the new position.
Buds often drop off in very hot weather, or if they are not getting the right amount of water. Heavy rain after a dry spell can also cause bud drop. An infestation of hibiscus beetle is another cause. This small black beetle feeds on unopened and developing flower buds and you will see holes in the flowers. Make traps for these pests using white ice cream containers part-filled with water and a squirt of washing up liquid. The beetles are attracted to the white colour and will drown in the soapy water. Pick up fallen buds daily and tie them in a rubbish bag to prevent spread of this pesky beetle and other diseases.
You might notice that leaves turn yellow and drop off following sudden changes in rainfall or temperature. Don’t worry, this is normal and your plant will quickly recover and new growth should appear after a week or two.