Q: I live near the Chattahoochee River. This time of year I see thousands of big white flowers with red centers in the marshy soil. They almost look like a large hibiscus bloom. What are they?

A: Your eyes are correct; they are hibiscus, probably ^Hibiscus moscheutos^ (swamp hibiscus).
Swamp hibiscus, as its name indicates, tolerates damp, but not constantly soggy, soil. If you can give it a spot that stays relatively moist and is in full sun you can grow it. Be sure to give this plant room: it grows to six feet tall but dies to the ground each winter.