In the winter when the deciduous plants have dropped their leaves, the evergreens really stand out. If we go for a walk, especially in the older neighborhoods, what evergreens do we see? The greatest numbers are spruces, firs, pines and junipers. In general these conifers with their narrow needles or scales are adapted to our cold temperatures, strong winds and sunny winter days. But there are other woody evergreens to be seen in Colorado neighborhoods: the broad-leaf evergreens. In general their wide leaves transpire more and are more prone to desiccation in our drying conditions; however by choosing the right plants and siting them in their right places, we can enjoy these less popular but deeply satisfying winter-green shrubs and vines. In this article I will discuss the easy broad-leaf evergreens for Colorado and in the April issue we will talk about the difficult ones.
One of the easiest broad-leaf evergreens, native to Colorado and still little known is Mountain Mahogany. Cercocarpus ledifolius and C. intricatus are simply fabulous. Light gray multiple trunks and narrow, thick green leaves beautify these shrubs. C. ledifolius grows to15’ and makes a very successful evergreen screen or specimen, even in full sun and low water. Cercocarpus intricatus looks much the same but only gets to 5’. Another evergreen Mt. Mahogany, C. breviflorus has a lobed leaf much like the deciduous C. montanus. There is a 10’ specimen at DBG that doesn’t look as good in winter as it does in summer, but it needs more testing.
There are four successful evergreen species of Mahonia for our area. Mahonia aquifolium, the holly-like Oregon Grape, has yellow flowers followed by blue berries, growing to 5’. It has a compact variety which only gets to 2 ½’ and Mahonia repens, our native, only grows to 6”-12”.These do best with some shade and protection from the winter sun and with some water, but they can also prosper in full sun with little water, though in winter the leaves will sunburn on the south side. Also doing well here are two desert mahonias with bluish leaves, yellow fragrant flowers and red fruit. Mahonia fremontii and M. haematocarpa are especially gorgeous in the early spring with their reddish new growth, but beware; for self-survival they can drop 10% of their spiny leaves in late fall which dry to needle sharpness and lie in wait for ungloved hands doing spring cleanup. I’ve discovered another use for my shopvac.
There are plenty of ivies that will die or dry up in our sunny winters, but there are several that are a luscious deep green on the north sides of buildings, walls and trees, breathtaking in the white snow. Hedera helix, English Ivy, varieties ‘Thorndale’, ‘Bulgaria’, ‘Baltica’, and ‘Wilsonii’ are successful and I’m sure there are others. Some ivies will tolerate sun, especially as a ground cover, but they excel in shade. In fact in dense shade where grass will barely exist, ivy can make a dense thick carpet. Ivy does get woody with age, flowers inconspicuously and draws bees by the hundreds. If allowed to have their way in conifers, they can weaken them. In the northwest, ivy is a noxious weed; and even here with water and shade it can take over. But given a north wall or a dark strip between the sidewalk and the house, ivies can work evergreen magic.
Euonymus has both deciduous and evergreen members in Colorado. Of the evergreen kinds all do well in part shade. Most useful are varieties of Euonymus fortunei: ‘Coloratus’ can be both a 1’-2’ high groundcover or a 6’-8’ vine whose shiny green leaves turn a purple-red in winter without dying. It can be unruly, but especially if kept on the dry side can be very beautiful in sun or shade. E. fortunei ‘Sarcoxie’ stays dark green all winter and be grown as a vine to 8’-12’ or as a shrub to 4’-5’. E. fortunei ‘Kewensis’ is very low 4”-8” spreading to 12” with tiny leaves. It is excellent and tidy. E. fortunei ‘Vegetus’ had large round leaves with a good strong climbing habit, or is trainable as a shrub. Often it can have an abundant crop of orange berries. In many older neighborhoods there are superb specimens of evergreen euonymus that appear to be some E. fortunei varieties. Some are 20’ tall, some are in full sun with southern exposure, some are serpentine tree-like, some are loose hedges along a fence, and some are groundcovers under dense conifers.
Another easy broadleaf evergreen, though little known, is Paxistima myrsinites, the native Mountain Lover. It has dark green roundish leaves and prefers part shade. Though it can get to 2’ high, mine in the dry shade of a buffaloberry is only 3” high and 8” in diameter, though it is possible that mine is actually another species, Paxistima canbyi. It any case it is a treasure, especially in winter.
Other easy broadleafs are the yuccas whose green blades piercing through the white snow look wonderful; Big Sage, looking silvery and wild; Cowania mexicana which is rather sparcely clothed in winter, but a great plant with fragrant creamy flowers; and several ephedras whose leafless green stems are like wild green waves. These four are also both natives and drought tolerant.
In the next issue: the difficult broadleaf evergreens for Colorado.