Osteospermum is a true perennial in its native South Africa, where mild winters let the plant persist and flower year after year. In most of Europe, North America, and other regions with freezing winters, however, it is treated as an annual because it cannot survive prolonged cold. This dual identity confuses gardeners who see it labeled both ways at the nursery, but the explanation is straightforward: the plant’s lifespan depends almost entirely on how cold your winter gets.
A Perennial That Acts Like an Annual in Cold Climates
In its homeland along the southern and eastern coasts of Africa, Osteospermum grows as a woody-based perennial, sometimes becoming a small subshrub over several seasons. The genus belongs to the daisy family (Asteraceae), and wild populations thrive in conditions that rarely dip below freezing. When the plant was introduced to European and North American horticulture, breeders marketed it heavily for spring and summer color. The problem is frost: Osteospermum has little tolerance for temperatures much below about −2 to −4 °C (roughly 28–25 °F), and a sustained freeze will kill the roots outright. Research on cold tolerance in Osteospermum has confirmed that in European climates, the plant behaves as an annual because winter cold kills it before it can complete a second growing season.1Plant Physiology and Biochemistry. Metabolic response to cold and freezing of Osteospermum ecklonis overexpressing Osmyb4
This makes Osteospermum a “tender perennial,” a category that includes many popular bedding plants like lantana, pelargonium (zonal geraniums), and calibrachoa. They are perennial by nature but get killed by winter in temperate and cold climates, so gardeners replace them each spring. If you garden in USDA hardiness zones 10 through 11, or comparable frost-free areas, your Osteospermum will return on its own year after year. In zones 9 and below, you either treat it as a one-season plant or take steps to protect it over winter.
Where Osteospermum Survives Year-Round
The dividing line is essentially whether your winter brings hard frost. In coastal Southern California, parts of Florida, the Mediterranean coast, much of coastal Australia, and lowland New Zealand, Osteospermum grows as a reliable perennial. Plants in these areas can develop woody stems and spread into sizeable mounds over two or three years. Some gardeners in zone 9b report success keeping plants alive through winter if they are grown against a south-facing wall or in a sheltered courtyard where radiant heat buffers the coldest nights.
In the United Kingdom, most of mainland Europe north of the Mediterranean fringe, and USDA zones 8 and colder in North America, outdoor Osteospermum will not make it through winter without intervention. A single night dropping below about −5 °C is usually enough to destroy the crown. Even in areas where winters are technically mild, wet and cold soil can rot the roots before frost ever arrives, because the plant evolved in well-drained sandy or rocky ground.
Growing It as an Annual
For most gardeners, treating Osteospermum as an annual is the simplest approach. Plants are widely available as spring bedding from garden centers starting in March or April, depending on the region. They flower prolifically from late spring through autumn, producing daisy-like blooms in white, purple, pink, orange, yellow, and bicolor patterns. Many modern cultivars have been bred for compact habit and continuous flowering, which makes them ideal for containers, hanging baskets, and border edging.
Because they are sold as seasonal bedding, Osteospermum plants at the nursery are often quite young and actively growing. They transplant easily into garden soil or pots and begin flowering almost immediately if given full sun. Feed them with a balanced fertilizer through the growing season. Research on potted Osteospermum crops has explored both continuous liquid feeding and controlled-release fertilizer approaches, finding that continuous fertigation tends to deliver more nitrogen to the plant but also loses more to runoff, while controlled-release granules are more efficient at keeping nutrients in the root zone.2Spanish Journal of Agricultural Research. Effect of different fertilization strategies on nitrogen balance in an outdoor potted crop of Osteospermum ecklonis (DC.) Norl. ‘Purple Red’ under Mediterranean climate conditions For home gardeners, a slow-release granular fertilizer mixed into the potting soil at planting time, supplemented by occasional liquid feeds during peak bloom, is a practical strategy.
When the first hard frost arrives, annual-treatment Osteospermum will blacken and collapse. Pull the plants, compost them, and plan to buy fresh stock the following spring. There is no shame in this approach. The plant gives months of color for a modest price, and fresh nursery plants tend to be more vigorous than overwintered ones anyway.
Overwintering Strategies for Colder Zones
If you have a favorite cultivar or simply dislike throwing away a living plant, you can overwinter Osteospermum indoors. The key requirements are cool temperatures (around 5–10 °C or 40–50 °F), bright light, and minimal watering. An unheated but frost-free greenhouse, a bright porch, or even a cool windowsill in a garage can work. The plant will not look impressive during winter; it may drop most of its leaves and go semi-dormant. That is normal. Reduce watering to just enough to keep the soil from going bone-dry, and do not fertilize until spring.
In early spring, once nighttime temperatures are reliably above freezing, you can move the plant back outside. Harden it off gradually over a week or so by placing it in a sheltered spot during the day and bringing it in at night. Once established outdoors again, trim any leggy or dead growth and resume regular watering and feeding. The overwintered plant will typically begin flowering a few weeks earlier than newly purchased nursery stock, which can be a nice reward for the effort.
Taking cuttings in late summer is another option. Stem-tip cuttings about 8–10 cm long, stripped of lower leaves and stuck into moist perlite or a seed-starting mix, root easily in a few weeks. Rooted cuttings take up far less space than a full-sized plant over winter, and they produce vigorous new growth in spring. Many commercial growers propagate Osteospermum almost exclusively from cuttings rather than seed, because named cultivars do not come true from seed.
The Summer Slump
A quirk that catches many gardeners off guard is that Osteospermum can stop flowering, or flower poorly, during the hottest part of summer. The plant evolved in a climate with moderate temperatures and is at its best when daytime highs sit between roughly 15 and 25 °C (60–77 °F). When temperatures climb above 30 °C (86 °F) for extended stretches, flower production slows or pauses entirely. The plant is not dying; it is simply waiting for cooler conditions. Once temperatures moderate in late summer or early autumn, a fresh flush of blooms usually appears.
This behavior leads some gardeners to conclude their Osteospermum is finished and pull it prematurely. If you live in a region where midsummer heat is intense but autumn stays mild, be patient. Cut the plant back lightly in midsummer, keep it watered, and let it recover when the heat breaks. In tropical or subtropical climates where it rarely drops below 30 °C even at night for months on end, Osteospermum can be a frustrating choice because the summer slump may last the entire growing season. In those areas, cooler-season planting (autumn through spring) works better.
How Osteospermum Differs From True Annuals
A genuinely annual plant, like a marigold or a zinnia, is genetically programmed to complete its entire life cycle in one season: germinate, grow, flower, set seed, and die. Even in a frost-free environment, a true annual will eventually senesce and die after it has reproduced. Osteospermum does not work this way. Given favorable conditions, it will keep growing indefinitely, getting woodier at the base and larger with each passing year. It does not “finish” after setting seed. This distinction matters if you are deciding whether to invest in overwintering, because the plant genuinely can live for years if protected from cold.
Some gardeners notice that older Osteospermum plants become leggy and less floriferous after two or three years, even in mild climates. A hard prune in early spring, cutting back to about a third of the plant’s height, usually restores compact growth and heavy flowering. Without periodic pruning, the plant tends to develop long, bare lower stems with a tuft of foliage and flowers only at the tips, which is not particularly attractive. This woody-perennial tendency is part of what separates it from a true annual: it is building a permanent structure rather than spending all its energy on a single season of flowers.
Popular Species and Cultivar Differences
Most Osteospermum sold at garden centers are hybrids, often derived from Osteospermum ecklonis and Osteospermum jucundum (sometimes listed under the older name Dimorphotheca). O. ecklonis types tend to be upright, reaching 30–60 cm tall, and are the ones most commonly sold as bedding plants. O. jucundum is naturally a lower, spreading plant that is somewhat hardier than O. ecklonis, sometimes surviving winters in sheltered spots in zone 8. If perennial performance matters to you and you garden in a borderline climate, look for cultivars bred from O. jucundum or labeled as “hardy Osteospermum.”
A few cultivars marketed specifically for improved cold tolerance include selections from the ‘Sunny’ series and some from the ‘Purple Sun’ lineage, though hardiness claims vary by source and real-world results depend heavily on local conditions. No Osteospermum cultivar currently on the market is reliably hardy below about −7 °C (around 20 °F), so even the toughest selections remain marginal in zone 7 and hopeless in zone 6 or colder without winter protection.
Seed-Grown Versus Vegetatively Propagated Plants
Osteospermum can be grown from seed, and several seed strains are available, but most of the named cultivars you see at nurseries are propagated from cuttings. This matters for a couple of reasons. Seed-grown plants tend to be more variable in flower color and growth habit, which is fine if you want a mixed planting but inconvenient if you want a uniform border. Cutting-propagated plants are genetic clones of the parent and will match the catalog photo exactly.
From a perennial-versus-annual standpoint, there is no meaningful difference. Both seed-grown and cutting-grown Osteospermum are equally tender and will either survive winter or not based on the same temperature thresholds. Seed-grown plants may take a bit longer to reach flowering size, which can feel like a disadvantage in a short growing season, but once established, they perform the same way.
Pests, Diseases, and What Actually Kills Them
Cold is the most common killer, but it is not the only one. Osteospermum is susceptible to root rot in waterlogged soil, especially during cool, damp weather. Good drainage is non-negotiable. If you are growing in containers, use a free-draining potting mix and make sure pots have adequate drainage holes. In garden soil, raised beds or sloping sites help shed excess moisture.
Aphids are the most frequent pest, congregating on new growth and flower buds. They rarely kill the plant but can distort growth and spread viral diseases. A strong spray of water knocks most aphids off, and ladybirds (ladybugs) handle the rest if you avoid broad-spectrum insecticides. Whitefly can also be a nuisance, particularly on plants overwintered indoors where natural predators are absent. Yellow sticky traps near the plant help monitor and reduce whitefly populations in an indoor setting.
Downy mildew occasionally attacks Osteospermum in humid conditions, causing yellowed leaves with a grayish fuzz on the undersides. Improving air circulation around the plant and avoiding overhead watering are the best preventive measures. Fungicide sprays are available but rarely necessary if growing conditions are reasonable.
Osteospermum Versus Dimorphotheca
Gardeners sometimes encounter Dimorphotheca at the nursery and wonder if it is the same plant. The two genera are closely related and were once lumped together, which is why older gardening books may use the names interchangeably. In current taxonomy, they are separate genera. The practical difference for gardeners is that most Dimorphotheca species sold commercially (like D. sinuata, the rain daisy) are true annuals. They complete their life cycle in one season regardless of climate. Osteospermum, as covered above, is perennial by nature. If the label says Dimorphotheca, you probably have a genuine annual. If it says Osteospermum (or the common name African daisy, Cape daisy, or blue-eyed daisy), you have a tender perennial that may or may not act as an annual depending on where you live.
Confusingly, “African daisy” is also used for Arctotis and Gazania, two other South African daisy genera with different care requirements. When buying plants, the Latin name on the label is more reliable than the common name for knowing what you are getting. Gazania, for what it is worth, is also a tender perennial with a very similar hardiness profile to Osteospermum, though it tends to tolerate heat and drought somewhat better and is a bit less bothered by the summer slump.