Radiant Pink Rose Mallow Flower Garden Seeds 200 Seeds Add a pink spotlight of color to your garden with the Rose Mallow flower. Rose Mallow adds a burst of pink to your garden with large 4? hibiscus shaped pinkish flowers that bloom from summer until fall. Grow in full sun. Try planting seeds in groups of 3-4 with ample space. Rose Mallow (aka Tree Mallow) stands up to 4? tall with 4? wide pink blooms. Plant your seed directly in their garden home; flower frowns about transplants. Zone 1-10. Annual. Lavatera trimestris. Feed your Rose Mallow regularly throughout the growing season. Heavy feeder. Likes normal to moist soil and thrives in clay, sand, or soggy soil types.