Astilbe 'Color Flash' Hardy in USDA zones 4 through 11. In zones 5 and below, add some extra mulch (wood, chopped leaves, etc.) around the plants if snow-cover is not expected. In warmer climates, make certain that it does not dry out over winter/cooler months.
HOW TO GROW ALLIUM GIGANTEUM FROM SEED |The Garden of Eaden