Germination temperature
About 18-21 °C (64-70 °F).
Flower growing guide
Osteospermum, the perennial African daisy, germinates in 7-10 days in warmth but flowers best when the nights turn cool. This guide covers sowing, the cool-night trick for more buds, and the diseases to watch for.
About 18-21 °C (64-70 °F).
Cover the seed only slightly.
About 7-10 days.
No light requirement recorded; a thin cover is recommended.
None needed.
Best started in trays or pots and planted out.
Osteospermum seed is large enough to space by hand. Sow a few seeds per cell or space them evenly in a seed tray so seedlings can be lifted without tearing roots.
Not needed. Seed-starting guidance lists no seed-coat treatment for osteospermum.
Not needed. The seed germinates in warmth; cool temperatures matter later, for flowering, not for germination.
Not needed. Sow into evenly moist seed compost.
The RHS recommends sowing at 18 °C (64 °F); the University of Alaska seed-starting chart gives 21 °C (70 °F). Aim for a steady temperature within this range.
Cover the seed only slightly with fine compost or vermiculite. No source gives an exact depth.
A light, free-draining seed compost. Osteospermum needs good drainage at every stage; growers keep the potting mix at about pH 6.0-6.2.
Keep the compost moist but never soggy. Seedlings are prone to root rots in cold, wet compost.
Seed charts list no light requirement and advise a slight cover. Give seedlings strong light as soon as they emerge so they stay compact.
About 7-10 days at the recommended temperature.
Move seedlings to individual small pots once they can be handled by their first true leaves. Keep them in bright light and do not overwater.
Plant in full sun, in light, moderately fertile, very well-drained soil, ideally in a warm spot sheltered from cold winds. Plants grow about 30-45 cm (12-18 in) tall and suit beds, rockeries and containers.
Pinch the tips once to make bushier plants. Osteospermum forms flower buds when nights fall below about 13 °C (55 °F); commercial growers give 7-13 °C (45-55 °F) nights for four weeks after side shoots appear for the heaviest bud set.
Cause: nights too warm. Frequent high temperatures reduce flowering. Fix: grow osteospermum in the cool season; flowering returns when nights cool down.
Cause: warm temperatures, low light or too much nitrogen feed. Fix: grow in full sun, feed moderately and pinch young plants.
Cause: root and crown rots such as Phytophthora in wet soil, or Verticillium wilt. Fix: plant in very free-draining soil or raised beds, avoid overwatering and remove affected plants.
Cause: powdery mildew or downy mildew. Fix: space plants for airflow, water the soil rather than the leaves and remove infected leaves early.
Cause: aphids, thrips or spider mites. Fix: check the undersides of leaves regularly and treat early.
Many varieties stop blooming in summer heat and flower again when nights cool. In the Indian plains sow after the monsoon for flowers through winter and spring; in the hills it can flower from spring into autumn.
Like other African daisies, the flowers close at night and in cloudy weather. Full sun gives the best display.
Osteospermum is a perennial subshrub. Seedlings from a mix vary in colour; to keep an outstanding plant, root softwood cuttings in late spring or semi-ripe cuttings in late summer. It tolerates light frost but not hard freezes.
Too much fertiliser, especially ammonium-based feed, makes plants stretch. A moderate, balanced feed is enough.
Sow osteospermum for large, glossy African daisies that flower through the cool months.
Most likely heat. Osteospermum sets buds when nights fall below about 13 °C (55 °F) and flowers less in hot weather. Keep plants healthy and they will flower again as nights cool.
No light requirement is recorded. Cover the seed slightly and keep it at about 18-21 °C (64-70 °F); seedlings usually appear in 7-10 days.
It is a perennial subshrub from South Africa, often grown as an annual. Where winters are mild and the soil drains well, plants can live for several years.
Seed-raised osteospermum varies in flower colour, so expect a range of shades from a mix. Keep the ones you like by taking cuttings.