The rose mallow's botanical name is Lavatera trimestris. It's a shrub that grows to 3 feet tall. In spring, it blooms with a profusion of large pink flowers that are reminiscent of the hibiscus. But you needn't live in a tropical climate to grow the rose mallow; it does well as an annual in colder regions and often survives the winter in milder regions. It occurs in the wild in scattered areas of the United States; you'll find it in California, Texas, Connecticut, Missouri and Vermont, although it originally came from Europe, according to the USDA Plants Profile Database.
Plant your rose mallow in a spot that gets full sun most of each day in the summer. This plant needs good drainage, so areas with small, gravelly rocks make good habitats.
Dig organic compost into your planting area if your soil is heavy clay that does not drain well, or if your soil is very sandy and drains too quickly. Using your shovel, scoop out the soil to make a planting hole twice the size of the plant's root system. Place it into a wheelbarrow and then add compost in an approximate ratio of one part compost to every four parts soil. Refill your planting hole about half full and then set your unpotted mallow into it. Fill with the remaining soil-compost combination and pat it down gently with your foot.
Water your newly planted rose mallow well by setting a hose at its base and letting water run slowly onto the soil around the base. After planting it, allow the soil to dry out before you water it again. Giving your mallow a good, deep soaking every 10 days or so should be adequate. Be sure to check the soil moisture if the weather is hot; water it more often if dryness occurs.
Fertilize your rose mallow with a balanced plant food that has an N-P-K ratio of 10-10-10 or 13-13-13 beginning about one month after you plant it. Repeat your application of fertilizer once each month until the plant begins to show flower buds, then fertilize it with a lower nitrogen fertilizer to force more blooms.
Prune your rose mallow in late winter if it has survived the winter cold. Cut off all dead and damaged branches to ground level and leave healthy branches about 10 inches long.