Growing Hibiscus

Hibiscus love Queensland’s warm climate. With the right position and a little regular care, they’ll reward you with flowers for most of the year.

Choosing a spot

• Sun: give them at least six hours of sun a day. More sun means more flowers.
• Shelter: protect them from strong winds, which damage the large flowers and dry the plant out.
• Drainage: hibiscus hate wet feet. If your soil is heavy clay, plant in a raised bed or mound.

Soil and planting

Hibiscus prefer a rich, well-drained soil that is slightly acidic (about pH 6 to 6.5). Dig in plenty of compost or well-rotted manure before planting. Plant at the same depth the plant was growing in its pot, water in well, and spread a layer of mulch around the plant, keeping it a few centimetres clear of the stem.

Many exotic hybrids are grafted onto a hardier rootstock. Keep the graft above the soil, and rub off any shoots that grow from below it, or the rootstock may take over.

Watering

Water deeply rather than often, so roots grow down into the soil. In the warmer months hibiscus need steady moisture to keep flowering, especially in pots. Ease off in winter when growth slows, and never leave plants sitting in water.

Feeding

Hibiscus are hungry plants. Feed them little and often from spring through autumn with a fertiliser made for hibiscus or flowering shrubs, following the directions on the pack. Water before and after feeding. Pale leaves with green veins can be a sign the plant needs trace elements such as iron or magnesium.

Pruning

Hibiscus flower on new growth, so pruning means more flowers. In south-east Queensland the main prune is usually done in late winter to early spring (around August to September), once the cold weather has passed.

• Use clean, sharp secateurs.
• Remove dead, weak and crossing branches first.
• Cut back by up to about a third, just above an outward-facing bud.
• Tip-prune through the growing season to keep plants bushy.

Growing in pots

Hibiscus grow well in large pots with a good-quality potting mix. Pots dry out quickly in summer, so check them often. Feed regularly, and refresh the potting mix or pot up every couple of years.

Pests and problems

• Aphids, mealybugs, scale and whitefly: sap-sucking insects that cluster on new growth and under leaves. Hose them off, or treat with horticultural oil or insecticidal soap.
• Hibiscus flower beetle: small beetles that get into buds and flowers and can cause buds to drop. Pick off and dispose of affected flowers and fallen buds.
• Erineum (leaf blister) mite: causes distorted, lumpy growth with a felty coating. Prune off and bin affected growth.
• Bud drop: usually a sign of stress, such as irregular watering, sudden temperature changes or pests.
• Yellow leaves: a few are normal, but many can point to over- or under-watering or a lack of nutrients.

Always read and follow the label directions on any garden chemical.

The hibiscus year in south-east Queensland

Season	What to do
Spring (Sep–Nov)	Finish pruning, start regular feeding, mulch, watch for aphids on new growth
Summer (Dec–Feb)	Water deeply and often, keep feeding, check pots daily, watch for beetles and mites
Autumn (Mar–May)	Peak flowering and show season, last main feed, take cuttings
Winter (Jun–Aug)	Water less, protect from cold in inland areas, plan your prune for late winter

More growing guides

• Cultural Notes: Jim Purdie’s detailed month-by-month program for Brisbane, including fertiliser mixes, potting mixes and pest control
• Propagation & Grafting: cuttings, side, wedge and bark grafts, standards and air layering, with Wally Morgan’s step-by-step photos
• Societies & Registration: other hibiscus societies, and how to register a new cultivar with the International Hibiscus Society