How to grow Hibiscus in New Zealand
The edible hibiscus grown in vegetable gardens is roselle (Hibiscus sabdariffa), a tender annual grown for the fleshy red calyces that wrap its seed pods. They make a tart, cranberry-red tea, cordial and jam, and the young leaves and flowers are edible too. Roselle needs a long, hot season, so it is best suited to the warm north of New Zealand.
📖 Our full guide: How to Grow Hibiscus in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | September to December | |
| Auckland | September to December | |
| Waikato & Bay of Plenty | October to December | Plant from October, once the inland frosts are over in late September. Warm coastal Bay of Plenty gardens can start a few weeks earlier under cover. |
| Central North Island | November and December | |
| Wellington & Lower North Island | October to December | |
| Nelson & Marlborough | October to December | |
| Canterbury | November and December | |
| Otago & Southland | November and December | |
| Central Otago | December |
Not to be confused with: Ornamental garden hibiscus, the tropical and hardy shrubs grown for their flowers. Their calyces are not the roselle crop.
Where to plant
Roselle needs full sun, warmth and shelter, in deep, fertile, humus-rich soil that drains well. It is very sensitive to frost and does not grow until the soil is properly warm.
It is a short-day plant: it grows leaves through summer and only flowers once the days begin to shorten in late summer and autumn. The calyces then need several more weeks of warm weather to fatten, so in cooler districts frost or cold can arrive before there is much to pick.
- Northland and Auckland: the best districts. Sow from late September to December, ideally October and November, for calyces in autumn.
- Waikato and Bay of Plenty: sow from October once inland frosts are over. Warm coastal Bay of Plenty gardens can start a few weeks earlier under cover.
- Wellington and Nelson and Marlborough: sow in October to December in the warmest, most sheltered spot, or grow it in a tunnel house. Crops of calyces are uncertain.
- Central North Island, Canterbury, Otago and Southland, and Central Otago: sow in November or December under cover. Outdoors, expect leaves rather than a useful crop of calyces.
How to plant
- Wait until frosts have well and truly passed and the soil is warm. Seed germinates in 7 to 14 days at 22 to 28°C.
- Sow two seeds per spot about 12 mm deep, direct in a sunny, compost-rich bed, and thin to the stronger seedling.
- Alternatively, sow into biodegradable pots indoors and plant out without disturbing the roots, as roselle transplants poorly.
- Space plants 60 cm to 1 m apart; wider spacing encourages more buds and better airflow.
Watering and feeding
Water regularly, especially while plants are young, to keep growth steady. Roselle likes plenty of moisture through summer but not waterlogged soil.
Dig in compost before sowing and side-dress with a balanced fertiliser or liquid feed through summer.
Harvesting
After each pale yellow flower drops, the red calyx around the seed pod swells. Pick the calyces when they are full-grown, plump and still tender, about 90 to 120 days from sowing. They snap off easily by hand, best in the morning; use clippers if the stems have toughened. They ripen from the bottom of the plant upwards, so pick over several weeks.
To use them, cut around the base of each calyx and push out the green seed pod. Use the calyces fresh for tea, cordial, syrup and jam, which sets without added pectin, or dry them and store in a sealed jar. Young leaves can be cooked as a tangy green.
Growing in pots
Roselle grows well in a large pot at least 40 cm wide in a hot, sheltered spot such as a sunny deck or tunnel house. Keep it well watered and fed. A pot can be moved under cover in autumn to protect late calyces from cold.
Varieties
- Roselle (Hibiscus sabdariffa)
Companion planting
Roselle is a tall, bushy annual that needs its own space and airflow. Grow it at the warm, sunny back of a summer bed.
Good companions
- Tropical plants (other tropical plants that like the same warmth and humidity)
Pests and diseases
Roselle has few problems in New Zealand home gardens. Cold, rather than pests, is the usual limit.
Pests to watch for
- Aphids Clusters on new shoots and flower buds.
- Mealybug White, cottony insects at leaf joints and on calyces, with sticky honeydew.
Diseases to watch for
- Leaf spot Brown spots on leaves in humid weather. Space plants for airflow and water the soil, not the leaves.
- Dieback
Common questions
Is roselle the same as garden hibiscus?
Roselle is a hibiscus, Hibiscus sabdariffa, but it is a tender annual grown for its edible red calyces. Ornamental hibiscus shrubs are grown for their flowers.
Why has my roselle not flowered?
Roselle only flowers as the days shorten in late summer and autumn, so it grows leaves all summer first. Sow in October or November so plants are big by autumn, and grow it in the warmest spot you have.
Can I grow roselle in the South Island?
Only under cover. Outdoors, frost or cold weather usually arrives before the calyces develop. In a tunnel house or glasshouse it is worth trying, and the young leaves are edible either way.
When do I pick roselle?
Pick the red calyces when they are plump and full-grown but still tender, usually from late summer into autumn, starting at the bottom of the plant.
How do I make roselle tea?
Remove the seed pod from each calyx, then steep fresh or dried calyces in hot water. The tea is tart and deep red; sweeten it to taste. The calyces also make cordial and a jam that sets without added pectin.
Can I save roselle seed?
Yes, if the season is long enough. Leave the last pods on the plant to mature and dry, then shell out the seed. In cooler districts the pods may not ripen before frost.
Sources we checked: Kings Seeds NZ: Roselle; Purdue University, Fruits of Warm Climates (Julia Morton): Roselle.