Hibiscus syriacus 'Rosi' has huge lavender flowers in mid summer to fall. This is a shrub or small tree that grows 8 -10 feet high and is hardy in zones 5 – 9. Hibiscus syriacus 'Rosi' is sold commercially as FULL BLAST. The name Hibiscus came from the Greek word “hibiskos” that meant “marshmallow.” The sticky root or stem of some plant in the mallow family was used at one time to make marshmallow confections.