Astilbes - flower for gardens

Flower & Garden Magazine, May, 2001 by Bonnie Blanchette

I like the way drifts of astilbes create ribbons of color in my mixed borders. Swathes of white, pink, red and purple astilbes make my shade gardens come alive in the summer. Without them, my shady borders would have to rely primarily on foliage for interest after the early-blooming plants have flowered. Instead, like botanical fireworks, one astilbe variety, then another, and another, bursts into bloom. * Astilbes have soft flowers and fern-like foliage that look great nestled against the coarse leaves of husky hostas. Like perfect companions, these plants complement each other throughout the growing season, but are especially stunning together when the astilbes produce their plume-like flowers or panicles. Some astilbes have lacy flowers that arch over their neighbors; others have stiff, upright panicles. Varieties with wispy flowers add a light, airy texture to my garden, while those with dense, bushy blooms add bolder strokes of color.

Astilbes vary in size as well as form. They can range in height from under one foot tall to about four feet. `Purple Lance' is an astilbe with spear-like flowers that rise above the horizontal layers of the garden and help link the shorter plants with the shrubs and trees in the background. Like delphiniums in a sunny bed, spiky astilbes create upward movement and make my shade garden more inspiring.

Each astilbe variety flowers for about three weeks. I am fortunate because my long borders provide enough space to include many different varieties. Since bloom periods vary among varieties, I have astilbes in flower from mid-June to mid-August. The focus in my border shifts from one area to another as different astilbes come into bloom. Instead of dead-heading them after they flower, I leave the dried reddish panicles on the plants and enjoy them well into late fall.

* NOT JUST FOR SHADE

Astilbes can be woven into sunny beds as long as they receive plenty of moisture. I grow `Pumila' at the sunny end of my border and many other varieties in a sunny area of my vegetable garden where I propagate perennials. I mulch the astilbes to help keep the soil moist and cool and water them frequently. Not only do they grow well, they flower more heavily than the same astilbes I grow in afternoon shade. Since astilbes make wonderful cut flowers, I use some of the extra flowers to add height and sweet fragrances to my summer bouquets.

* GROWING ASTILBES

Regardless of whether I'm growing astilbes in sun or shade, I add compost and peat moss to my sandy soil before I plant to help create the moisture-retentive soil they demand. I've noticed that astilbes that dry out to the point where the leaves shrivel, never seem to regain their vigor, so I water them on hot, windy days and during dry spells. Astilbes are heavy feeders, so I also provide them with a balanced time-release fertilizer in the spring.

I divide astilbes every three to four years before they decline and produce fewer flowers. I either use a sharp, serrated knife to saw the woody crowns into three or four sections, or I slice through the plant with a shovel. Then I replant each piece in soil amended with organic matter. Mid-to-late August is the best time to divide so that plants have a chance to develop new roots before winter. I've found that astilbes are tough plants and easy to grow as long as they do not dry out.

* DESIGNING WITH ASTILBES

Whether astilbes dance in the shade with their perfect partners, hostas, or skip gracefully through the sunny border, they always add an element of softness to a garden. Unlike daylilies and hostas that can stand alone, astilbes should be planted in drifts, because one plant doesn't make much of an impact. I plant them in groups of three, five, or seven, depending on the size of the variety and how much space I have available. I've found that dense plantings of astilbes make my garden look lush. Drifts of astilbes also create large enough splashes of color to move the eye along my border and make it appear more fluid.

Few perennials are as easy to place in the garden as astilbes. I plant varieties at the front of the garden, mid border or in the background, depending on their height. Then, I select companion plants that are in scale with the astilbes and have contrasting leaf textures. I've found that fine-textured plants like ferns don't pair well with astilbes because their leaves are too similar. I prefer to couple astilbes with plants that have coarser leaves, like coral bells (Heuchera), lungworts (Pulmonaria) and hostas.

In addition to contrasting textures, I also add interest to my garden by using color to link the astilbes with neighboring plants. Pleasing combinations result when the astilbe echoes a color in a nearby annual or perennial. I like the crispness of white astilbes near green-and-white hostas and the subtle melding of lavender astilbes with purple daylilies. I also like to place the astilbes where they'll be the most effective, so I often use white and pale pink varieties to brighten dark areas of my garden. Red astilbes can get lost in too much shade unless they are backed by a light-colored variety that blooms at the same time. I suggest planting red astilbes in sun or lightly-shaded areas near purple foliage, since red flowers enhance purple leaves.