 | Radius Astilbe. Cold-hardy and bold red plumes, the Radius Astilbe (Astilbe x 'Radius') is an outstanding new hybrid False Spirea that kicks off the spring when the foliage emerges dark red before maturing to dark green for the rest of the growing season! Radius blooms profusely in mid-summer when the dark-red flower buds open to deep rose-red plumes that butterflies and hummingbirds love! Radius blooms are slightly fragrant and make great cut flowers for bouquets and can even be dried for botanical arrangements.... - Radius Astilbe. |