Rose of Sharon Hibiscus syriacus be grown as a large multi-stemmed shrub or trained into a single stem small tree, 10-12 ft. tall. It is very late to leaf out, sometimes as late as June. It is useful as a hedge, screen or background plant. It tolerates full sun to partial shade, clay soils, heat, wind and cold. The flowers bloom August through September, and are rose, lilac, white or a bluish-purple. This plant is not bothered by rabbits, squirrels nor deer. Also known as shrub Althea.