First, you must understand that I, an Osteospermum, am a tender perennial. My genetic lineage hails from the warm, sunny climates of South Africa. This means I am not inherently equipped to survive freezing temperatures. My cells contain a high water content, and when that water freezes, it expands, rupturing cell walls and causing fatal damage. My survival through the colder months is entirely dependent on the climate of your specific garden and the interventions you provide. The USDA Hardiness Zone is crucial here. If you garden in zone 9 or above, where winters are consistently mild, I may survive outdoors with minimal protection. In zones 8 and below, I will require significant help or need to be brought indoors to see another spring.
In regions where hard freezes are a rarity, my needs are simpler. As autumn progresses and daylight wanes, my blooming will naturally slow and cease. This is my signal to enter a period of dormancy, conserving energy for the next growing season. Before the first frost is anticipated, please give me a gentle haircut. Trim back my spent flowers and any leggy or overly long stems by about one-third to one-half. This pruning is not for aesthetics alone; it removes growth that is most vulnerable to cold damage and prevents me from expending energy on these parts. Apply a fresh 2-3 inch layer of mulch, such as bark chips or straw, around my base. This blanket is vital as it insulates my root zone, protecting my crown—the critical point from which all new growth emerges—from sudden temperature dips.
If you live where winters are harsh, the most reliable strategy is to bring me inside. The best time to do this is in mid-fall, before any frost threatens. Carefully dig me up, trying to keep my root ball intact. Pot me in a container with fresh, well-draining potting mix. Once potted, you have two choices for my indoor accommodation. The first is to treat me as a houseplant. Place me in a cool, bright room like a sunny south-facing window. I will likely not flower much, if at all, but my foliage will remain alive. Water me sparingly, only when the top inch of soil is dry, as my growth has slowed dramatically. The second, and often easier, option is to encourage full dormancy. Place my potted form in a cool (40-50°F / 5-10°C), dark location such an unheated garage or basement. Water me very lightly just enough to prevent my roots from completely desiccating. I will drop my leaves and appear dead, but I am merely sleeping.
As the grip of winter loosens and daylight increases in late winter or early spring, it will be time to wake me. For dormant plants, move my pot into a warmer, brighter space and begin watering more regularly. You will soon see new green shoots emerging from my crown. For those kept as houseplants, you can simply increase watering. A few weeks before your last expected frost date, begin the process of "hardening off." This involves placing me outdoors in a sheltered, partially shaded spot for a few hours each day, gradually increasing the time and exposure to direct sun over 7-10 days. This gradual acclimatization is essential to prevent sunscald on my tender new leaves. Once all danger of frost has passed, I can be replanted in the garden or have my pot placed in its summer location, ready to grow and bloom vigorously once again.
