Astilbe x arendsii Hybrid Astilbe, False Spirea Size: 2 to 4' high by 24 to 30" wide. Hardiness: Zones 4 to 9. Heat Zones: 8 to 2. Habit: 'Fanal' is an early red bloom with dark bronze leaves. Fern like foliage. Culture: Full Sun to deep shade.