University of Vermont Extension 
Department of Plant and Soil Science

Anytime News Article


CHOICE PERENNIALS FOR 2010

 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
 
How do you decide what perennials to choose from among the thousands available?  A good place to start might be those voted the top for this year of the Perennial Plant Association, the industry group representing growers and professional garden designers, from which the perennial of the year will be selected.  The top choices of perennial professionals from across the country include relatively new cultivars (cultivated varieties) as well as a less known species.

'Northwind' is an ornamental switchgrass (Panicum virgatum) with bluish-green foliage, compared to the green of the species or reddish of some cultivars.  It is also one of the most upright of the switchgrasses, many tending to flop over with age later in the season.  The 4 to 5-foot clumps are topped, late in the season, with one to 2-foot flowery plumes called "panicles" of small yellowish flowers.

As with all switchgrasses it prefers full sun and a moist and fertile soil.  It will tolerate sandy or clay soils, and drought once established.  It is hardy to much of the north (USDA zone 4 or -20 to -30 degrees F average low in winter). This perennial looks good in masses, in the middle to back of borders, on slopes, and combined with many other perennials.

'Caramel' is one of the many new coralbells (Heuchera), grown mainly for its apricot leaves in light and dark shades.  It does flower in warm areas with light pink small flowers on spikes above the foliage in early summer.  This is one of the selections of the hairy coralbells (H. villosa), a southeastern U.S. native, although it originated as a chance seedling in France.  Under good conditions and warm climates it can reach 15 inches high and a bit wider. 

'Caramel' is listed as hardy to USDA zone 4, with trials underway at the University of Vermont on the hardiness of this and other coralbells.  It does best in full sun in the north if kept watered, part shade in the south.  The best soil for it is a rich, moist loam but well-drained.  Try 'Caramel' in masses in borders, under shrubs such as roses, along edges of beds and paths, and in containers.  Contrast the leaf color with that of darker blackish coralbells, or contrast the leaf texture with ornamental grasses. 

The thread-leaf blue star (Amsonia hubrichtii) is not hardy in all of the north (USDA zone 5 or -10 to -20 degrees F average winter low).  Where it does grow this less common perennial, native to the mountains of Arkansas, provides a mound of powdery blue, star-shaped flowers in early summer in the north.  Plants form a mound 2 to 3 feet tall and wide.  It provides a fine feathery texture with its thread-like leaves that turn gold in fall. 

Like other bluestars, this one grows best in full sun in the north, and moist but well-drained soil. It will tolerate dry soil once established.  Also it will tolerate some shade, but may flop and have less showy fall color.  It is best massed in borders, by itself, native plant gardens, or individually in rock gardens.  It combines well with blue woodland phlox (Phlox divaricata).

Recent Perennial Plant of the Year winners that you might consider too include the golden Hakone grass and hellebores (both generally hardy to zone 5), 'Rozanne' perennial geranium, 'Walker's Low' catmint, 'Becky' shasta daisy, 'David' garden phlox, and Japanese painted fern.  More on these, and other winners, can be found online (www.perennialplant.org).
 

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