Osteospermum, commonly known as the African Daisy or Cape Daisy, is a vibrant flowering plant. This South African native is a tender perennial, meaning it is capable of living for multiple years. Whether it returns every year depends entirely on your specific geographic location and local climate, as its survival is tied to the severity of winter temperatures.
Understanding Annual Versus Perennial Status
The designation of Osteospermum as an annual or perennial is determined by its ability to survive the cold season. African Daisies are reliably perennial only in climates where the ground does not freeze deeply, specifically in USDA Hardiness Zones 10 and 11.
In these milder zones, the plant can continue to grow and bloom for several years. In Zones 9 and below, the plant is typically treated as an annual due to its sensitivity to cold. It will usually die once temperatures drop below about -5°C (23°F). Gardeners in cooler regions must either replant every spring or take action to protect the plant from winter weather.
Active Techniques for Overwintering Success
Gardeners in marginal climates, such as those in Zone 8 or a sheltered Zone 7, can attempt to keep their established Osteospermum plants alive through the winter. This relies on providing adequate insulation or temporary indoor protection. For plants remaining in the ground, preparation should begin in late autumn before the first hard frost.
Applying a thick, loose layer of organic mulch, such as straw or shredded leaves, over the root zone helps to moderate soil temperature. This insulation shields the crown and roots from the damaging effects of repeated freeze-thaw cycles, which can heave the plant out of the soil. Siting the plant near a south-facing wall or structure offers further protection from cold winds and helps capture residual warmth.
A more reliable method involves bringing potted plants indoors to a cool, bright location. Before moving the container inside, prune the plant back lightly, removing any weak or damaged growth to reduce the risk of fungal disease. The plant should be inspected thoroughly for pests, such as aphids or whiteflies, which can spread rapidly in an indoor environment. During its indoor dormancy, the plant requires only minimal water, allowing the soil to dry out almost completely between light waterings, and should be kept in temperatures above freezing, ideally between 45–55°F (7–13°C).
Ensuring Future Blooms Through Renewal
For gardeners in cold regions where outdoor survival is impossible, or for those who prefer not to manage a dormant plant indoors, renewal methods focus on creating entirely new plants from the existing one before cold weather arrives. The most common and effective method is taking softwood stem cuttings in late summer or early fall.
To propagate, select a non-flowering shoot about two to three inches long and make a clean cut just below a leaf node. Dipping the cut end into a rooting hormone powder can accelerate the formation of new roots. These cuttings are then placed in a well-draining, sterile rooting medium, such as a mix of perlite and compost, and kept in a bright, warm, and humid environment indoors.
Alternatively, some varieties of Osteospermum can be grown from seed, though many modern hybrids may not produce offspring identical to the parent plant. Seeds should be started indoors six to eight weeks before the last expected frost date in spring. This ensures the seedlings are robust enough to transplant outside once all danger of frost has passed, providing a fresh display of African Daisies for the new season.