Dark Blue Tweedia is a tender perennial flower that brings an uncommon jewel tone to summer and fall gardens. With delicate, star-shaped blooms in a striking deep blue, this South American native (Oxypetalum caeruleum) grows to a compact 24 inches tall and wide, reaching full flower in 84 to 98 days from seed. Hardy in zone 10, it thrives in full sun and moderate water, attracting pollinators while resisting deer browsing, making it a rewarding choice for both containers and garden beds.
1
Full Sun
Moderate
10-10
24in H x 24in W
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High
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The deep blue flowers are genuinely distinctive in a garden landscape, arriving reliably from late spring through the first frost if you're in a warm enough zone. Unlike many blue flowers that fade or shift tone, Dark Blue Tweedia holds its color with remarkable clarity. Starting these from seed indoors eight weeks before your last frost is straightforward and rewarding; you'll have blooming plants in under three months. The compact, mounding form means it works equally well in containers or tucked into flower borders without overwhelming neighboring plants.
Dark Blue Tweedia is grown purely for its ornamental flowers. The star-shaped blooms are excellent as fresh-cut specimens for small arrangements and bouquets, and the airy stems add graceful texture when combined with other summer flowers. In warm climates, it functions as a long-season container plant or garden accent that flowers continuously from summer into fall.
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Sow seeds indoors 8 weeks before your last frost date. Sow on the soil surface and cover lightly with vermiculite or use a humidity dome to maintain moisture. Keep the soil consistently moist and maintain temperatures between 68 and 75°F. Seedlings will emerge in 7 to 14 days. Transplant into individual pots once they develop true leaves and grow under bright, indirect light until outdoor conditions warm.
Harden off seedlings by gradually introducing them to outdoor light and air over 7 to 10 days. Transplant outdoors after your last frost date when soil has warmed. Space plants 1 inch apart for dense bedding, or 12 to 18 inches apart for individual plants with more mature fullness.
Direct sow seeds outdoors after all frost danger has passed. Sow on the surface and keep the soil consistently moist until seedlings emerge in 7 to 14 days.
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