Rosie O'day is a compact sweet alyssum that brings delicate, honey-scented flowers to gardens across zones 5 through 11. This frost-tolerant cultivar grows just 4 inches tall but spreads 6 to 12 inches wide, making it a natural choice for edging beds, containers, and rocky slopes where you want continuous color without fuss. The variety thrives in full sun with moderate water and tolerates cool springs, flowering reliably from late spring through fall in most climates.
Full Sun
Moderate
5-11
4in H x 12in W
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Moderate
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Rosie O'day delivers vibrant color in an incredibly compact footprint, staying just 4 inches high while spreading outward to create dense, flowering mounds. Its frost tolerance means it can be direct sown weeks before your last spring frost and will often continue blooming into autumn, extending the season in ways taller varieties cannot. In mild climates, fall sowing produces winter bloom, giving this variety a surprising second act when most flowers have faded.
Sweet alyssum flowers are traditionally used to add delicate fragrance and soft color to cutting gardens and mixed borders. The nectar-rich blooms attract pollinators, making them valuable in gardens focused on supporting bees and butterflies. In containers and window boxes, Rosie O'day's compact, spreading habit creates a long season of blooms without requiring heavy deadheading.
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Start seeds indoors 4 to 6 weeks before your average last frost date. Maintain a soil temperature between 60°F and 85°F for reliable germination. These seedlings can then be transplanted outdoors after hardening off.
Transplant seedlings outdoors 4 to 6 weeks before your average last frost date, or after the last spring frost depending on your region. Space plants 6 to 12 inches apart to allow for their mature width. Harden off seedlings by gradually exposing them to outdoor conditions over 7 to 10 days before planting in the garden.
Sow seeds directly outside 1 to 2 weeks before your average last frost date, when soil temperature reaches 60°F to 85°F. In mild climates, fall sowing is recommended for winter bloom. Press seeds lightly into the soil surface without covering them, as light aids germination.
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