Hibiscus: types, growing from seed, pruning and overwintering

In short: The name hibiscus covers several plants. For the garden, the frost-hardy Syrian hibiscus is the one, flowering from July to September and tolerating roughly −20 °C. Chinese hibiscus is a houseplant and roselle gives calyces for red tea. From seed they are all grown similarly: soak, sow in February to March and keep at 20–25 °C. Germination takes 2–6 weeks and the seeds quickly lose viability.

Hibiscus is one of the few plants that only come into full flower in August, when the garden is fading. The large flowers in violet, pink, white or blue each last only a day, but the shrub opens dozens a week. All it needs is a sunny spot and a little patience in spring, as it sprouts as one of the last shrubs. If you are interested in the edible relative, okra, read the separate article edible hibiscus, or okra.

Which hibiscus for the garden, which for the home and which for tea

The genus Hibiscus has hundreds of species, but in Czech gardens and homes you will mainly meet four. They differ mainly in frost hardiness, and hence in where you can grow them.

When someone talks about hibiscus in the garden, they almost always mean Syrian hibiscus. The rest of the article focuses on it; for the other species we give the main differences.

Varieties of Syrian hibiscus by colour

In garden centres, Syrian hibiscus is sold mainly as named varieties. These four are among the most widespread, and all hold the Award of Garden Merit of the British Royal Horticultural Society (RHS). The data on colour, flower size and height come from the RHS database.

Varieties are propagated by cuttings or grafting. From seed, whether from your own shrub or bought, you will get a hibiscus whose colour may not match the mother plant. Anyone who wants a specific variety buys a young plant; anyone who likes surprises and cheap plants for a hedge sows seed.

From seed to flower: sowing and two to three years of waiting

Syrian hibiscus grows easily from seed; you just have to reckon with the first flowers usually arriving in the second to third year. In return you get hardy plants at a fraction of the price of young plants.

1. Fresh seeds. Hibiscus seeds quickly lose viability. Sow seeds from the latest harvest; with your own seeds, the surest way is to sow them soon after they ripen.
2. Soaking. Soak the seeds for 12–24 hours in lukewarm water. The hard coat softens and the seeds begin to swell.
3. Sowing. In February to March, sow them in seed compost to a depth of about 5 mm, each seed separately in a cell of a seed tray or a small pot.
4. Warmth and moisture. Keep 20–25 °C and the compost just moist, not wet. Covering with film helps retain moisture; ventilate daily.
5. Emergence. Seedlings usually appear after 2–6 weeks, unevenly. Put emerged seedlings straight on the brightest windowsill, otherwise they will stretch.
6. Pricking out. At 3–4 true leaves, transplant into 9–10 cm pots with good-quality compost.
7. Outdoors. From the end of May, harden the plants off and in the first year grow them in a container or in a sheltered bed. Plant them in their permanent place in spring of the second year.

The same procedure applies to swamp rose mallow. For roselle, timing is decisive: sow it in February at the latest. It is a short-day plant that sets flowers only when the days shorten at the end of summer, and the calyces then need another 2–3 weeks of warmth. Outdoors in the Czech Republic they often do not have time to ripen before the first frosts; a greenhouse or polytunnel is surer. You will find general sowing tips in the article germinating seeds by type of plant.

Position, soil and care

Syrian hibiscus wants full sun, at least 6 hours a day. In partial shade it grows but flowers noticeably less. It suits a warm corner of the garden, next to the house or as a freely growing hedge.

• Soil: loamy, humus-rich and free-draining, pH neutral to slightly acidic. It does not tolerate waterlogging.
• Watering: regular in summer, especially for young shrubs and when buds are setting. In drought it drops its buds.
• Feeding: a fertiliser for ornamental woody plants in spring, and during summer top up once or twice if needed. Not after August.
• Mulch: 5–8 cm of bark or wood chips retains moisture and protects the roots in winter. In the first two winters, heap it around the roots of young plants; older shrubs need no winter protection.

Chinese hibiscus in the home needs the brightest window, 12–18 °C in winter and less watering. In summer it can go outside onto the terrace, but bring it back indoors at night below 10 °C. You will find more about caring for houseplants in winter in the article overwintering houseplants.

Pruning Syrian hibiscus

Syrian hibiscus flowers on the current year's shoots, so it is pruned in spring, from March to April. Pruning encourages branching and a greater number of flowers.

1. Remove dry, frozen and inward-growing branches.
2. Shorten last year's shoots by a third to a half, above an outward-facing bud.
3. Rejuvenate older, congested shrubs by cutting out the 2–3 oldest branches at ground level.

Swamp rose mallow is pruned differently: in autumn or early spring, cut dry stems down to the ground; new ones will grow from the roots. Shorten Chinese hibiscus by a third in February to March.

Hibiscus tea: only from roselle and with caution

The well-known ruby-red tea with a sour taste is not made from the flowers of garden hibiscus but from the fleshy calyces of roselle. The calyces are harvested roughly 2–3 weeks after flowering, when they are fleshy and bright red, then separated from the seed capsule and dried in shade.

For a 250 ml mug, 1–2 teaspoons of dried calyces are enough; steep with hot water and leave for 5–10 minutes. The tea is drunk warm or cold and combines well with rosehips or mint. The growing of other herbs for tea is described in the article on mint and its uses.

Warning: hibiscus tea may lower blood pressure and influence the effect of some medicines. In animal experiments, the calyx extract changed the blood level of the diuretic hydrochlorothiazide and of the blood pressure drug captopril. Anyone taking medicines for blood pressure or for fluid retention should first consult a doctor before drinking hibiscus tea. Do not drink it in pregnancy.

And one more thing people ask about: a true essential oil from hibiscus is practically not produced by distillation, as the flowers contain it only in traces. Products with a hibiscus scent tend to be a macerate in a carrier oil or a fragrance oil.

Why hibiscus drops its buds and other problems

• Bud drop. The cause is usually drought, a sudden change of temperature or moving the plant while flowers are setting.
• Late bud break. Syrian hibiscus sprouts only in May, swamp rose mallow even in June. Wait before you dig the shrub up.
• Aphids and spider mite. Check young shoots and the undersides of leaves, especially on houseplant hibiscus in dry air.
• Self-seeding. Syrian hibiscus readily self-seeds in the garden. If you do not want seedlings all over the bed, remove the capsules in autumn.

Frequently asked questions

When does Syrian hibiscus flower?

From July to September, and in a warm autumn even in October. A single flower lasts a day, but the shrub gradually opens a great number of them.

Is hibiscus frost hardy?

Syrian and swamp hibiscus are; they tolerate roughly −20 °C. Chinese hibiscus and roselle do not tolerate frost and must be kept warm in winter.

Why is my hibiscus not sprouting in spring?

Syrian hibiscus is among the latest-sprouting shrubs; it often puts out its first leaves only in mid-May. Scrape the bark on a branch; green tissue means it is alive.

How long does it take for hibiscus to flower from seed?

Syrian hibiscus from seed usually flowers in the second to third year. Swamp rose mallow and roselle can flower already in the first year if sown early.

How do I overwinter hibiscus in a pot?

Overwinter Syrian hibiscus in a container in a cool, bright or even dark room at a temperature of 0–8 °C and water only occasionally. Keep houseplant Chinese hibiscus in the light at 12–18 °C.

Can I drink hibiscus tea if I take blood pressure medicines?

Only after consulting a doctor. Hibiscus tea may lower blood pressure and influence the effect of blood pressure medicines and diuretics. Do not drink it at all in pregnancy.

What you will need for sowing

The recommended products are from our range. We do not yet have roselle or swamp hibiscus seeds in it.

• Syrian hibiscus (Hibiscus syriacus), 10 seeds – a frost-hardy garden species, the one the whole procedure above is based on. The flower colour from seed is not guaranteed.
• Seed-sowing compost 5 l – a fine compost in which soaked seeds emerge evenly. It is already too poor for transplanted plants.
• MULTI seed tray 4 × 4 cm – each seed in its own cell, transplanting without damaging the roots. Small cells dry out quickly.
• Fertiliser for ornamental woody plants 1 l – spring feeding of an adult shrub for abundant flowering. Do not feed after August.

Sources

• Hibiscus syriacus 'Oiseau Bleu' (Royal Horticultural Society)
• Hibiscus syriacus 'Hamabo' (Royal Horticultural Society)
• Have the hibiscus seeds ripened in your garden? Sow them straight away (Naše zahrada)
• Herb-drug interaction between Hibiscus sabdariffa and hydrochlorothiazide in experimental animals (J Med Food, 2011)
• Pharmacokinetic herb-drug interaction between Hibiscus sabdariffa calyces extract and captopril in rats (Evid Based Complement Alternat Med, 2020)

Updated: 27 September 2026