Swamp Rosemallow
Hibiscus grandiflorus
Last reviewed: September 2026
Hibiscus grandiflorus, the swamp rosemallow, is a tall wetland forb with large pink flowers blooming June through September. It grows best in full sun with consistently wet to moist soil, common in marshes and ditches across the Gulf Coast and Southeast.
Toxicity unknown
Swamp Rosemallow (Hibiscus grandiflorus) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.
Light
full sun
Water
high
Size
36"–96" H × 24"–48" W
Bloom
Jun, Jul, Aug, Sep
Native to
AL, FL, GA, LA and 3 more states
Pollinators
bees, butterflies, beetles
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Swamp rosemallow produces spectacular large pink or white hibiscus flowers up to 8 inches across from summer through early fall. This tall native perennial thrives in consistently moist conditions and can reach 8 feet in height. It dies back completely in winter but returns reliably each spring.
Growing Swamp Rosemallow
Grow Swamp Rosemallow in full sun and high water. Mature plants reach 36 to 96 inches tall and spread 24 to 48 inches wide. Expect moderate maintenance to keep it looking intentional in a front yard.
How to care for Swamp Rosemallow, by region
How to care for Swamp Rosemallow where it is actually grown: year-round basics plus what to do each season, region by region, with the sources for each.
Care guidance last updated: October 2026
Erie Drift Plain (includes Buffalo, NY)
Year-round
Swamp rose mallow is a tall perennial with big pink flowers that likes wet soil and part shade.
- Plant it in wet or consistently moist soil, like a low spot or pond edge.
- The source lists part shade and says it can reach about 10 feet.
- It grows easily from seed planted in spring.
Fall
In fall the plant winds down, and Buffalo frost usually arrives around mid October.
- Keep watering if fall is dry.
- Let seed and stems finish before tidying.
- Mulch the root zone before hard freezes.
Winter
In winter it is dormant, and the sources I found do not give cold hardiness, so treat it as a plant to watch in Buffalo.
- No cold hardiness rating was found in the source, so winter survival in Buffalo is unconfirmed.
- Keep a layer of mulch over the roots.
- Check for new growth in late spring before deciding anything.
Spring
Spring is the time to sow seed and get the soil ready, but wait until frost has passed in Buffalo.
- Sow seed in spring, since it grows easily that way.
- Wait for the late spring frost danger to pass before planting out.
- Choose a wet, part shade spot.
Summer
Summer is when it grows tall and flowers, as long as the soil stays wet.
- Keep the soil wet, never dry out.
- Expect large pink flowers with dark centers.
- Give it room since it can get very tall.
Sources: Lady Bird Johnson Wildflower Center: Hibiscus grandiflorus
In an HOA neighborhood
Swamp Rosemallow takes more care to keep looking intentional in a front yard. Maintenance level: moderate. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Grows very tall and can appear overgrown
- Dies back completely leaving bare stems in winter
- Requires consistently wet soil conditions
Wildlife value
The large showy blooms attract bees, butterflies, and beetles throughout the long flowering season. Seeds provide food for birds in fall and winter.
Common questions
- When does swamp rosemallow bloom?
- Swamp rosemallow typically flowers from June through September, producing large showy pink blooms through the summer into early fall.
- What growing conditions does swamp rosemallow need?
- This forb prefers full sun and consistently wet to moist soil, making it well suited to pond edges, marshes, ditches and rain gardens rather than dry beds.
- What pollinators are attracted to swamp rosemallow?
- Bees, butterflies and beetles regularly visit the large flowers of swamp rosemallow to feed on pollen and nectar.
- Does swamp rosemallow die back in winter?
- Yes, it is a deciduous herbaceous perennial that dies back to the root system after frost and regrows from the base the following spring.
- Is Swamp Rosemallow HOA-friendly?
- Swamp Rosemallow takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.
These answers were drafted with an AI model from this plant's data. Verify care details with a local expert.
Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
If something looks wrong
Common plant problems, and what to check first
These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.
- It is dying right after planting
- Leaves turning yellow
- Wilting even though I watered it
- Brown crispy leaf tips
- Bugs on the plant
Ready to grow Swamp Rosemallow? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.