Extension Educator, Horticulture
Everywhere I look I see ghosts of gardens past. Apparitions of asters that once were brilliant purple, pink and blue stand among specters of spearmint, spiderwort and spirea. Phantasmal figures of the fruits of my labor are now brown bony stems. If your garden needs resuscitation then consider some perennials that don't turn to corpses late in the season.
Foliage is the key to winter interest in perennials. Late season lookers include many sedums, euphorbias, sedges, coral bells and sages. Some plant breeders have noticed people like me that are not willing to let a little cold put an end to life in the garden. Plant breeders have even marketed late season beauties such as Proven Winners Fall Magic series. Here are just a few plants that hang on to their good looks late in the season.
Euphorbia 'Efanthia' and Euphorbia 'Despina' are excellent in fall containers. Or put a few near the backdoor or out a patio window. They stay upright at about 8-10 inches tall. 'Despina' has lance shaped leaves of dark green with steely blue overtones. 'Efanthia' has dark green leaves that turn burgundy purple as the weather cools. Both look nice no matter how cold the weather gets. Some sources list them as zone 6 so they may not be reliably winter hardy here. However they sure do put on a good winter show. Even their corpses are good looking.
Euphorbia 'Chameleon' is winter hardy. It has deep purple leaves during the summer that evolve into dark green with purple tones into winter. Beautiful plant at 12 to 18 inches. Its tight mound of foliage looks lovely right now nestled among some fall leaves. Next spring the tops of 'Chameleon' Euphorbia will explode into chartreuse flowers.
Myrtle Euphorbia, Euphorbia myrsinites, stays a steely blue well into winter. It tends to trail and ramble and propagate itself into other parts of the garden. The leaves are tight spirals around the fleshy stem and have a nice architectural appeal. But beware, like other Euphorbias, Myrtle Euphorbia exudes a white sap when stems are cut. The sap can produce poison ivy like blisters on some people. I have talked to several people who have developed this condition from Myrtle Euphorbia.
Coral bells also known has heucheras have come a long way in providing attractive leaves. New breeding programs have produced all kinds of leaf color variations. They do tolerate cold well. The leaves may slump a bit but they keep their color of purples, silver or gold. 'Amethyst Myst' (say that fast) has deep purple leaves veiled in silver. Mix coral bells with the intense velvety silver leaves of 'Icicles', Helichrysum thianschanicum.
Some spikey plants look particularly dramatic in a winter garden. Many of the ornamental grasses have turned to their fall color. Sedges look like grasses and most are very cold tolerant.
'Toffee Twist' Sedge, Carex flagellifera, has a graceful look to it with its arching slender leaves. The reddish bronze leaves form a 12 inch tall fountain.
Leather-Leaf Sedge, Carex buchananii, adds a certain elegance to a garden or container. It has delicate thin leaves of bronze with an upright habit. It grows to about 12-16 inches tall.
'Ogon' Acorus, Acorus gramineus, is another grass like plant with a very upright habit, actually more like a series of fans. 'Ogon' is evergreen or better said evergold with chartreuse and cream variegated leaves. 'Ogon' is Japanese for golden. Acorus are excellent in wet areas and during the summer season can easily be grown in a bog garden or container water garden. For winter pop them into a high visibility spot in the garden.
The Proven winners website (http://www.provenwinners.com) has pictures of several of these plants that resurrect a winter garden.