About the time they give up on it completely and decide to buy a new one, it begins to grow. Although rose mallow can reach a height of 8 feet, it commonly only grows 3 to 5 feet high, Goodspeed adds. Although it is tall, the stems are generally sturdy enough to hold up the large blossoms, and seldom needs staking. It adapts to most soils, but prefers growing where it is well-drained and rich in organic matter. These perennial plants have striking blooms like the hibiscus, and even similar foliage.
Mallows look a little like a cross between a hollyhock and a hibiscus.
They can vary in size from 6 inches to about 6 feet. However, because they reseed, they can survive for many years in a perennial garden. The mallow plant is a bit too leggy and scruffy looking for my own taste. Insecticides are not very effective, but if insecticides are used they work best against the very young nymphs. If you plan to use insecticides, sprays should be applied when small nymphs are present, which generally occurs early in the season.