African Daisies (Osteospermum)

Q. Will Osteospermum seed come up in the spring in my zone 4/5 garden? Can the plant be dug up from the garden and grown inside in a pot over the winter to replant outside in the spring?

A. In your zone, African Daisies are definitely not hardy. Their seed may survive the winter but the germination would be low. It is best for you to collect seeds now, dry in envelopes, store, and sow next spring. Or, you may buy new seed and/or plants next spring. In temperate zones [9+], they will grow as a perennial.

Osteospermum:

Height: 12 inches
Spacing: 18 inches
Type: half-hardy annual
Flowers: White, pink, blue, purple, yellow

Plants are about a foot tall and will produce daisy-like flowers in various colors. The flowers sometimes have a darker and contrasting color in the center. The plants grow best in a well-drained soil and in full sun. In southern climates, excessive humidity may be a problem. The plants are native to Africa.

In your garden, grow in fertile, well-drained soil, in full sun. Yes, you may overwinter plants in frost-free conditions, in a well-lit window which is insulated from the cold outside. Water less, but keep growing and feed once a month with 30-10-10.

Sow in early spring, barely covering the seed with compost or soil. Make sure that the compost is moist but not wet and seal in a plastic bag until after germination which usually takes 10-15 days at 15-18C (60-65F). Do not exclude light which is beneficial to germination. Transplant when large enough to handle into 8cm (3in) pots and grow on in cooler conditions. Gradually acclimate to outdoor conditions for 10-15 days before planting out after all risk of frost, 30cm (12in) apart in a warm sunny spot on light well drained soil. A direct sowing can be made during late spring where they are to flower.

Cultivars: 'Salmon Queen' - Salmon colored flowers are displayed on trailing plants.
Suitable for use in hanging containers.

Silver Sparkler' - The white flowers have a dark blue center.
The foliage is variegated.

'Stardust' - Dark pink flowers.

References for Cultivars: White Flower Farm 1997