PERENNIALS FOR WINTER
Dr. Leonard Perry, Extension Professor
University of Vermont
Perennials for winter? No, I'm not suggesting that you travel to a warmer climate to see these at gardens (not a bad idea, though). Nor am I suggesting you try growing them indoors overwinter although some you can, especially if you have a cool space like an unheated bedroom or hallway with light.
What I am suggesting is that you consider choosing some perennials now, to buy and plant this next season, to give nice effects in the winter garden.
Of course, you won't have blooms on perennials in winter this far north, but the spent blooms and flower spikes can be quite attractive, especially rising up through the snow. The foliage of many ornamental grasses can be beautiful as well, especially covered with frost or ice.
Perennials with tall spikes, especially those that bloom in mid to late summer, often hold up well into winter. For shorter (one to two foot) perennials, consider the speedwells (Veronica). These are quite popular now, and generally hardy in the north.
Depending on the variety, these range from six inches to three feet tall. One I particularly like, and have had good luck with, is called 'Sunny Border Blue' (named after the wholesale nursery in Connecticut that developed it). It has six-inch flowers on spikes about two feet high that last several weeks. Even as a cut flower they can last up to two weeks in a vase.
Ligularia 'The Rocket' has tall yellow spikes midsummer, about three to four or more feet high. They keep their shape well after bloom, adding structure in fall and winter to the back of a border. These like moist feet, even wet at times, so place appropriately in your landscape.
The plume flower, or Astilbe, has many cultivars, most reaching around two feet high. In midsummer these thick plumes are generally red, pink, purple, or white. They have a nice tan or brown color into fall and winter. Cultivars range from six inches to three feet tall (usually the purple flower varieties). The taller ones like 'Superba' and 'Purple Candles' generally bloom later in summer, and again, last nicely into winter.
Then there are the other flower forms to consider for a winter garden. The golden black-eyed daisies, such as the Rudbeckia 'Goldsturm' have nice small cones on one to two foot stems in winter. Similar, but a little taller, are the coneflowers (Echinacea). These may be pink/purple or white and bloom later in the summer.
They can self-seed in the garden, so keep this in mind when deciding where to plant. Self-seeding is nice if you want a whole bed of them, or don't mind hoeing the seedlings out each year.
Helenium, or Helen's flower, is another good choice. This plant grows to heights of four or five feet with orange to red or yellow flowers in early fall.
Other perennials you might consider are the Joe-Pye Weed (Eupatorium 'Gateway'), which has five to six-foot purplish flowers in late summer with lasting bloom. Black snakeroot (Cimicifuga) has spikes six to eight feet tall. It produces white flowers in late summer, which will last into winter.
Some of the purplish leaf forms like 'Hillside Black Beauty' also are quite popular now. Or try perennial sunflowers (Helianthus), such as the common 'Summer Sun' or the new double 'Bressingham Doubloon.' These have golden yellow flowers in late summer. They grow three to four feet tall, forming large spreading clumps. They are sometimes self-seeding and will provide winter structure in the mid to back garden.
My favorites for the winter garden, however, are the ornamental grasses. Some, such as the Foxtail grasses (Pennisetum), are generally not hardy in our colder climate. Others, like the many Maiden Grasses (Miscanthus), may be marginally hardy in our area, depending on the year and cultivar.
One that seems quite tough ,though, is the purple-leaf variety (Miscanthus purpurescens). It forms a clump, which gets bigger but doesn't spread, and grows to four to five feet high. The silver plumes open in late summer and last all winter, with the purplish green foliage turning russet orange in fall then a nice brown through winter.
One Miscanthus to avoid, as it is totally invasive by its roots, is Miscanthus sacchariflorus. Once you have it, you may have it for life! You may read elsewhere that this genus of grasses is seed invasive. However, in the north, with our cooler climate and shorter season, these never seem to get the chance to go to seed, so seldom are a problem in this respect.
Other hardy favorites include the Moor Grasses (Molinia) with their tall, narrow spikes waving in the breeze. The Switch grasses (Panicum) are upright clumps, with one cultivar having reddish leaves ('Rotstrahlbush') and other new ones with bluish leaves (such as 'Cloud Nine' and 'Prairie Sky').
The Tufted Hair Grass (Deschampsias) form a mound of foliage about two feet high and across, with even taller arching spikes coming out late summer and turning a nice light brown through winter. These remind me of a fountain or exploding fireworks.
These are just a few examples of the many perennials to add to your garden for a four- season effect. Check with the experts at your local nursery or garden center for other suggestions.