Ceratostigma Forest Blue has beautiful cobalt blue flowers in summer and a nice, dark autumn colour. Forest Blue has a spreading, bushy habit and becomes approx. 100 cm high and 50 cm wide. Plant Blue Forest in full sun in a moist but well-drained soil. Prune in spring up to a height of approx. 10 cm. Ceratostigma Forest Blue is hardy to -15 ºC.