Luminary® Ultraviolet Tall Garden Phlox

Light Needs

Full Sun

(At Least 6 Hours Of Direct Sunlight)

Mature Height

32-36 Inches

Mature Spread

18-24 Inches

Growing Zones

3 to 8

Luminary® Ultraviolet Tall Garden Phlox shows off saturated magenta-violet flower panicles that stay bold in summer heat, backed by noticeably clean foliage. It reaches about 32–36 inches tall and 28–32 inches wide, making a solid mid-border anchor without needing a back fence to look right. The big advantage over older garden phlox is the improved resistance to powdery mildew, which is usually what makes customers give up on phlox in humid summers. This is our favorite phlox for fragrance and cut flowers, without the stems turning gray by August.

Phlox paniculata Luminary® ‘Ultraviolet’ is a North American native selection bred for stronger performance, blooming from summer into fall with repeat color when conditions are good. The flowers are fragrant and consistently draw bees, butterflies, and hummingbirds, enhancing pollinator and vegetable gardens. Its upright habit also makes it a strong “thriller” in large containers, especially for height that still feels soft and full. Give it air flow and steady moisture, and it stays remarkably presentable for a tall phlox.

Luminary® Ultraviolet Tall Garden Phlox Care

Grow Luminary® Ultraviolet Tall Garden Phlox in full sun for best flowering and the strongest mildew resistance, although part sun works if the site is bright and open. Plant in consistently moist, well-drained soil that’s average to fertile, with a slightly acidic to neutral pH (roughly under 7 is fine). Avoid cramped corners and dense plantings, since air circulation helps foliage stay disease resistant.

Water at the base when the top couple inches of soil begin to dry, and keep moisture even during bud set and bloom so flowers don’t stall. Phlox responds well to regular feeding, with a spring fertilizer and another light application mid to late summer to keep blooming strong without weakening stems. 

Deadhead spent panicles to extend the bloom window and keep the plant looking fresh, especially if you don’t want seedlings. If stems get tall and you prefer a fuller mound, cut plants back by about one-third in late spring to encourage branching. Once it goes dormant, cut stems down in late fall and remove debris to reduce carryover disease pressure. Divide every few years in spring to reinvigorate growth and keep the center from getting woody.

Luminary® Ultraviolet Tall Garden Phlox Spacing

Space plants 28–32 inches apart, allowing each clump to fill out while staying dry through the foliage. For containers, use a pot at least 16–18 inches wide so the root zone doesn’t dry too fast during peak bloom.

In the landscape, pair Luminary® Ultraviolet with coneflower for a long pollinator season and switchgrass for movement behind the flower panicles. In containers, combine it with petunias for spill and coleus for foliage contrast that makes the violet tones look even deeper.

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