Alligator Flag
Thalia geniculata
Varieties We Bring In
Last received Sep 23, 2026.
We bring this in seasonally, so what is on the lot changes week to week. A received date shows when it last came in, not that it is here today.
Call (904) 471-0440 to confirm this plant and size before you make the trip.
About Alligator Flag
Alligator Flag (Thalia geniculata) is a tall, native aquatic or marginal perennial found in marshes and freshwater wetlands from Florida through tropical America, with large, canna-like leaves and slender stems bearing small violet flowers. It is an important native wetland plant providing habitat and visual drama in water gardens and pond edges. Starting at $7.95.
Plant details
- Bloom Season
- Summer, Fall
- Flower Color
- Purple
- Growth Rate
- Fast
- Foliage
- Deciduous
- Soil
- Loam, Acidic, Wet
Best planting months
Seasonal care
New foliage emerges. Good planting window.
Bloom season. Higher water demand in summer heat.
Bloom season. Foliage may begin to change or drop. Ideal planting window.
Dormant — drops foliage.
Care essentials
Grow Alligator Flag in full sun to part sun; it thrives alongside ponds, ditches, and rain gardens throughout Northeast Florida and performs best with maximum sun exposure in standing or saturated water.
Alligator Flag is an aquatic or marginal wetland plant requiring consistently wet to flooded conditions; it grows naturally in swamps and freshwater marshes and should never be allowed to dry out.
Plant in loamy, moist to wet, slightly acidic soil or directly in shallow water up to 12 inches deep. No fertilizer is needed in natural settings; in managed water gardens, a light slow-release aquatic fertilizer can be added in spring.
Similar needs
Calla Lily
Shares 5 of the same needs: similar light, high water, loam, zone 9a hardiness, and pollinator-friendly.
Giant Ironweed
Shares 5 of the same needs: full sun, high water, loam, zone 9a hardiness, and pollinator-friendly.
Halberdleaf Rosemallow
Shares 5 of the same needs: full sun, high water, loam, zone 9a hardiness, and pollinator-friendly.
Scarlet Rosemallow
Shares 5 of the same needs: full sun, high water, loam, zone 9a hardiness, and pollinator-friendly.
Hardy Hibiscus
Shares 4 of the same needs: full sun, high water, loam, and pollinator-friendly.
American Hornbeam
Shares 5 of the same needs: full sun, high water, loam, zone 9a hardiness, and pollinator-friendly.
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Common questions
Is Alligator Flag a good plant for St. Augustine?
Alligator Flag is a perennial for Zone 9b coastal Florida gardens, reaching 6-10 feet × 4-6 feet.
Care information verified from
Last reviewed February 2026. Our care guidance comes from trusted horticulture sources and decades of helping St. Augustine gardeners. Conditions here can vary dramatically from one area to the next, so come ask us and we'll tailor it to your yard.