Dr. Leonard Perry, Extension Professor
University of Vermont
Resist the temptation to cut all those perennials back in fall just to look tidy and be ready for spring. Of course you’ll want to cut back any that are unsightly, flopped over (“lodged”), diseased, or lack vigor from summer stresses. But leave some perennials for their attractive fall foliage colors and seedheads. Those with seeds provide food for birds in preparation for winter. A few may even provide some late flower color.
For fall interest, lower plants will suffice. But for winter with its usual snow cover, you’ll want to consider leaving some taller perennials. Many ornamental grasses are a great late-season choice for either their foliage color or texture, or both. Some provide seeds to birds, too.
Some choices for blue foliage include a few of these ornamental grasses. ‘Elijah Blue’ fescue makes a nice bluish mound, under a foot high. Similar in color and habit, only much larger, mounding 2 feet high and wide, is the blue oat grass (Helictotrichon). More upright and open in habit, its bluish summer leaves turning quite tan in late fall, is little bluestem (Schizachyrium) and its cultivars (cultivated varieties). Another good low choice, other than grasses but still with narrow leaves, is the pinks or dianthus.
For a more upright effect, consider some of the switchgrasses (Panicum) with bluish leaves, such as the tall ‘Cloud Nine’ (6 feet or more tall), a bit shorter ‘Dallas Blues’ or ‘Prairie Sky’, or even shorter (4 to 5 feet tall) ‘Dewey Blue’ or ‘Heavy Metal’. Seeds of switchgrasses are attractive to small birds. Results of my trials in Vermont on both little bluestem and switchgrasses, as part of a larger national trial program, are online (perrysperennials.info).
Don’t overlook the blue and purple flowers of the late-blooming New England aster. If you prune these back by a third to half in June, they’ll be more branched, dense, and will bloom even later into the fall.
Contrasting nicely with bluish colors are plants with burgundy to purple leaves. Once again there are some 3 to 5-foot high switchgrasses to chose from, the best including Ruby Ribbons and ‘Hanse Herms’. Several others have some red leaves mixed among the green. In trials of little bluestem grass cultivars in Vermont, a new one from Minnesota— Blue Heaven— has very attractive dark red fall color on plants just over 2 feet high.
There are several 4 to 5-foot high cultivars of dark purple-leaved bugbanes (Actaea, formerly Cimicifuga) such as ‘Hillside Black Beauty’, ‘Brunette’, and ‘Black Negligee’. ‘Firecracker’ hairy loosestrife (Lysimachia ciliata) is a clumping, non-spreading species, 3 to 4-feet high with dark reddish leaves, as is the ‘Chocolate’ cultivar of white snakeroot (Eupatorium). The latter is best in warmer regions (USDA zone 5b, average minimum of -10 to -15 degrees F in winter).
Lower at under 2 feet high are some dark-leaved perennial geraniums, such as ‘Espresso’, ‘Midnight Reiter’, and ‘Elizabeth Ann’. Similar in height but more upright and less mounded is ‘Bressingham Purple’ Jacob’s ladder (Polemonium). Many such purple-leaved perennials will have less color, being more green, when grown in part shade rather than full sun. One that does hold its reddish-purple leaf color well through fall is the upright relatively new sedum ‘Postman’s Pride’. ‘Lady in Red’ painted fern (Athyrium) has bright red stems in mid-fall. ‘Bonfire’ cushion spurge (Euphorbia) has bright red fall leaf color, but needs a warmer climate (USDA zone 5b) or reliable snow cover to survive.
For even lower red to purple-leaved perennials, about a foot high, are the many dark-leaved coralbells (Heuchera). These include some of the top-rated in our Vermont trials (see the above research website) including ‘Blackout’, ‘Dark Secret’, and ‘Frosted Violet’.
While not perennial, the kale and cabbages are worth mentioning as they provide some of the best blue to dark red and purple leaves into late fall—often until Thanksgiving or after. Some are lower, a foot high, while others such as scarlet kale and crane bicolor kale reach two feet—the former with dark red fringed leaves, the latter columnar with pink to white coloring at the top.
There is a flower to mention too in this reddish color spectrum. ‘Sheffield Pink’ is a hardy chrysanthemum cultivar, blooming salmon pink in mid to late fall and one of the last plants to bloom. While it often survives in colder areas, the season may be too short for it to actually bloom.
For golden to yellow leaves, perennials are mainly the lower ones under a foot high. For taller gold leaves, you may need to use shrubs such as golden-leaved evergreens or conifers. You can get nice golden color from bluestars (Amsonia), growing two feet or more high and resembling a shrub. Or try Osmunda ferns for their upright golden long leaves, contrasting nicely with their brown “seed” stalks.
Some of the lower golden to yellow perennials for fall include ‘Angelina’ sedum, the golden creeping Jenny (Lysimachia), golden oregano, ‘Aztec Gold’ speedwell (Veronica), ‘Dickson’s Gold’ bellflower (Campanula), ‘Gold Bullion’ bluet (Centaurea), and ‘Illumination’ perennial periwinkle (Vinca). Golden hakone grass (Hakonechloa) is good in sun or part shade in warmer sites (USDA zone 5b). Some golden perennials, such as the bluet, the golden ‘Sweet Kate’ spiderwort (Tradescantia), or those with gold variegation, often revert to green leaves. To keep them golden or variegated you’ll need to cut off, or out, any such green shoots.
Then there are those with white or silvery leaves, often during the season and lasting through fall until they die back or are covered with snow. Most are low, under a foot high, such as the lungworts (Pulmonaria) with their silvery to silver-spotted leaves, or the popular compact ‘Silver Mound’ mugwort (Artemisia). There are a couple of taller silver mugworts too, such as ‘Silver King’, that can spread aggressively by their roots. There are a couple silvery cultivars of Siberian bugloss (Brunnera) such as ‘Jack Frost’ and ‘Looking Glass’. The white dead nettles (Lamium) are a spreading groundcover, some with quite white or silvery leaves.
Marginally hardy in cold areas, better in USDA zone 5, are the toad lilies. These Asian imports have very attractive white flowers, often speckled lilac, in mid fall just over a foot tall. For taller white flowers in fall are some asters, such as the heath aster (Symphotrichum ericoides), and the false chamomile ‘Snowbank’ (Boltonia asteroides), reaching 3 feet or more high.
One of the best for a shimmering silver effect through fall, from its 6 to 8 foot high flower plumes, is the silver banner grass (Miscanthus sacchariflorus). Be careful with this one and place in a bed by itself, as it is quite root invasive and will overpower most any other plant. I keep threatening to try and remove mine, but each fall the plumes redeem themselves for yet another season, particularly with backlighting from the low afternoon sun.
Keep the fall effect of your perennials in mind, both with fall pruning and with choosing plants for an extended season of color.
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