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Alligator Flag (Thalia geniculata), Perennial

Varieties We Bring In

StandardThalia geniculata
Sizes & Pricing
1 galFrom$9.95

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.

LightFull Sun, Part Sun
WaterHigh
Mature size6-10 feet × 4-6 feet

Pet toxicity: not on file, check before planting where pets chew

Pet safety guide

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.

Plant details

Bloom Season
Summer, Fall
Flower Color
Purple
Growth Rate
Fast
Foliage
Deciduous
Soil
Loam, Acidic, Wet

Best planting months

Recommended forZone 9b · St. Augustine, FL

Recommended months: March, April, May, September, October, November.

January, other month
February, other month
March, good window
April, good window
May, good window
June, other month
July, other month
August, other month
September, good window
October, good window
November, good window, this month
December, other month
This monthGood windowOther months

Seasonal care

New foliage emerges. Good planting window.

Care essentials

Light

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.

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.

Soil & Fertilizer

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

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Common questions

Is Alligator Flag a good plant for St. Augustine?

Alligator Flag is a perennial. Mature size: 6-10 feet × 4-6 feet. Light: Full Sun, Part Sun. Water needs: High. Alligator Flag is native to Florida. Recorded hardiness zone: 9a.

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.