Cut cv. Madelon rose buds do not open satisfactorily when kept under low light (LL) conditions, in contrast to cv. Sonia buds. Adding sucrose to the keeping solution or storage in high light (HL) helped Madelon buds to open, but probably two different mechanisms were involved. Satisfactory development of Madelon rose involved increased dry weight, but this was not essential for Sonia buds. The ‘blueing’ of petals under LL conditions occurs in both rose cultivars, but the phenomenon appears unrelated to cell pH. In the light of the results other factors possibly involved in promoting flower bud opening in Madelon and Sonia are discussed, but no complete explanation is yet available.