Originally published in 2006:
Some Minnesotans treat their flower gardens like cornfields: Once the stems turn brown in late fall, everything gets whacked to the ground.
That urge for tidiness does have a few advantages. Removing
diseased foliage and stems can help prevent disease next year. And
cutting back perennials in the fall means less work in the spring,
already a hectic time in the garden.
But before your inner farmer starts clear-cutting the flower bed,
consider these reasons to leave some stems, seedheads and climbing
plants standing all winter:
Imagine a few inches of fluffy snow piled in little turbans atop
purple coneflowers, dolloped like whipped cream on the broad
platters of Autumn Joy sedum or delicately outlining the arching
stems of ornamental grasses. Now you get the idea. Leaving some
perennials in the garden adds much-needed structure, texture and
visual depth to an otherwise flat winter landscape.
Besides coneflowers and sedums, good choices for winter structure
include stiff-stemmed prairie plants such as sunflowers, asters,
silphium and goldenrods. Also consider leaving up annual vines and
herbaceous perennial vines such as hops. Their looping stems add
vertical structure and catch snow in interesting patterns.
When perennials catch the snow, it does more than look pretty; it
also helps insulate the ground.
Wind often whisks snow off flat open areas. But stems, especially
the densely clustered stems that many perennials have, catch snow
so it accumulates around the vital crown and root areas.
Leave chrysanthemums (even those labeled "hardy") standing in the
fall because they benefit from an insulative layer of snow. Other
perennials that appreciate a blanket of snow are Russian sage,
hardy hibiscus (rose mallow) and coral bells.
Even when they're not crowned with snow, many perennials have
showy seedheads in winter. Some of the best-looking seedheads are
on ornamental grasses, especially Miscanthus cultivars such as
`Purpurascens,' with its silky silver-white plumes. Other
winter-interest grasses include Indian grass (Sorghastrum nutans),
switchgrass (Panicum virgatum) and the feather reed grasses
Interesting seed pods are also found on Siberian iris, balloon
flower (Platycodon grandiflorus) and martagon lily. And don't be in
a hurry to deadhead smooth and panicle hydrangeas. These woody
shrubs have attractive flower structures that keep their shape