Astilbe

Botanical/Latin
   Astilbe

Pronunciation
   a-Stil-bee

Common Name
   False Spirea

Hardiness zone range
   4 - 8

General Comments
Feathery flower plumes in shades of white, red, pink, and purple rise above the elegant, lacy foliage in early summer and into fall.

Uses
Indispensable near water features, they are superb when grouped in streamside gardens or on the edges of pools or ponds. They make effective ground cover in shady borders, damp areas, or when massed in moist, woodland settings. With careful selection, the color, flower types, and flowering times can be combined to make stunning displays that extend from June into August. If deer browsing is a problem, Astilbes may be a good choice since deer usually leave them untouched. They make excellent cut flowers; the best stage to harvest them is before the flowers become fully open.

Light Preference
Partial Shade. They will tolerate sunny conditions when sufficient moisture is present at their roots.

Culture
Tough, hardy, and pest free, Astilbes are reliable and easy to grow. Performing best in rich, moist soils that contain plenty of organic matter, they will tolerate most soil types except a thin chalk or a heavy clay soil that dries and cracks. Since clumps have a tendency to work their way to the top of the soil and older ones become woody, lose vigor, and have diminished flowering, they should be divided regularly, replanting the younger, outer crowns and mulching the surrounding soil. This helps to retain moisture and keeps them vigorous.

Background
Astilbes are native to China, Korea and Japan. The first plants reached Europe in 1825 when a wealthy British aristocrat, Lord Hamilton, introduced them. They were thought to resemble Spireas, so the common name False Spirea was applied. The botanical name comes from two Greek words: a (without) and stilbe (brilliance), probably referring to the individually small flowers, and perhaps to the fact that the earliest colors were whites and light pinks. They were cultivated for the cut flower trade and were not considered garden plants until the breeding work of Lemoine in Nancy, France and Georg Arends in Ronsdorf, Germany. They extended the color range and flowering times by hybridizing four species. They developed color breakthroughs that led to wonderful, new, award winning cultivars and, ultimately, as breeding parents that were used to develop many of the fine color variants we grow in our gardens today.

Splendor Suggestions
When dividing thick matted plants like Astilbes, rather than trying to pull them apart, cut out pieces with a spade (like sod from a lawn) and transplant them to the new position. We find this easier to do, and they seem to establish quicker.

Companion Plants
They are absolutely magnificent when massed together with other Astilbe cultivars. The colors seem to naturally blend well together. Pleasing effects have been achieved in borders or curving beds when a transition of color starts with bold, dark shades, gradually becoming paler as the eye progresses along the bed. Try with the wonderful ground cover and edger, Ajuga 'Burgundy Glow', with its tri-colored variegation and blue flowers. The bold, rounded, leaves of Hostas, particularly those with white variegation like H. 'Undulata', 'Albo-marginata', 'Patriot', or the frosty blue leaves of Hosta 'Krossa Regal', 'Halcyon' or 'Blue Angel' soften the bright colors and contrast the feathery spikes. Iris ensata (Japanese iris), Corydalis 'China Blue' or Lamium 'Shell Pink' also make good companions.

Pruning
If desired, the old flower stems and leaves can be removed to tidy and clean up the clumps. The rusty-brown seed heads can be an attractive feature in a fall or winter landscape; it is worth considering leaving them until the following spring.

Fertilization
A light dressing with a well balanced fertilizer should be applied in early spring, before the foliage emerges. We have found slow release formulations to be particularly effective.