Dianella Blue Stream A lovely grass-like perennial for milder areas, Dianella revoluta Blue Stream is a clump-forming, evergreen, perennial grass with broad, sword-like, light blue leaves. It produces blue flowers in warmer countries, but is unlikely to do so in Ireland; nevertheless, it is a striking and beautiful plant. Cut back to the ground before growth starts in early spring. Dianella Blue Stream is good in mass plantings in milder areas, where it may need winter protection, but it can also be grown in a container, brought in for the winter, as part of a single or mixed planting. Site: ShelteredSoil: Any well-drained soilPosition: Full sunSeason of interest: All yearHardiness: Borderline hardy – to -7ºCHeight: 28” (70cm) Spread: 20” (50cm)