Radius Astilbe flowers
(Photo courtesy of NetPS Plant Finder)
Height: 26 inches
Spacing: 18 inches
Hardiness Zone: 4a
Other Names: False Spirea, Astilbe x arendsii
Attractive deep red plumes, rising above rich green, glossy leaves; perfect in a shady spot with dappled light; prefers moisture so water regularly for abundant flowers and nice foliage
Radius Astilbe has masses of beautiful plumes of red flowers rising above the foliage from late spring to early summer, which are most effective when planted in groupings. The flowers are excellent for cutting. Its serrated ferny compound leaves remain dark green in colour throughout the season. The fruit is not ornamentally significant. The dark red stems are very colorful and add to the overall interest of the plant.
Radius Astilbe is an herbaceous perennial with an upright spreading habit of growth. Its relatively fine texture sets it apart from other garden plants with less refined foliage.
This is a relatively low maintenance plant, and is best cleaned up in early spring before it resumes active growth for the season. It is a good choice for attracting butterflies to your yard, but is not particularly attractive to deer who tend to leave it alone in favor of tastier treats. It has no significant negative characteristics.
Radius Astilbe is recommended for the following landscape applications;
- Mass Planting
- Rock/Alpine Gardens
- Border Edging
- General Garden Use
- Container Planting
Planting & Growing
Radius Astilbe will grow to be about 20 inches tall at maturity, with a spread of 24 inches. When grown in masses or used as a bedding plant, individual plants should be spaced approximately 18 inches apart. Its foliage tends to remain dense right to the ground, not requiring facer plants in front. It grows at a medium rate, and under ideal conditions can be expected to live for approximately 10 years.
This plant does best in partial shade to shade. It requires an evenly moist well-drained soil for optimal growth. It is very fussy about its soil conditions and must have rich, acidic soils to ensure success, and is subject to chlorosis (yellowing) of the leaves in alkaline soils. It is somewhat tolerant of urban pollution, and will benefit from being planted in a relatively sheltered location. Consider applying a thick mulch around the root zone over the growing season to conserve soil moisture. This particular variety is an interspecific hybrid. It can be propagated by division; however, as a cultivated variety, be aware that it may be subject to certain restrictions or prohibitions on propagation.
Radius Astilbe is a fine choice for the garden, but it is also a good selection for planting in outdoor pots and containers. With its upright habit of growth, it is best suited for use as a 'thriller' in the 'spiller-thriller-filler' container combination; plant it near the center of the pot, surrounded by smaller plants and those that spill over the edges. Note that when growing plants in outdoor containers and baskets, they may require more frequent waterings than they would in the yard or garden. Be aware that in our climate, most plants cannot be expected to survive the winter if left in containers outdoors, and this plant is no exception. Contact our experts for more information on how to protect it over the winter months.