Rose of Sharon Tree Form (Hibiscus syriacus)– Tree form plants are getting more popular and if you have ever seen a Rose of Sharon in bloom, then you know why. Reminiscent of the tropics, you will see an explosion of hibiscus like blooms in colours of white, red, blue or purple. Rose of Sharon is a late bloomer, flowering late summer and blooms until first frost providing exceptional interest when other plants are starting to wane.