The whole idea of winter gardening tends to rely a great deal too much on picturesque dustings of snow and delicate traceries of frost clinging to the remains of the ornamental grasses. Boston’s winter climate being rather short on dustings and traceries (floods and dumpings are more like it), I look for other ways to keep the garden going during the three coldest months. The plant that does the most to relieve the visual tedium at our place is a selection of the moosewood maple, a species native to the northeastern quarter of the United States and southeastern Canada. Now, the ordinary form of moosewood maple is handsome enough, for it is the sole North American representative (the others are all Asian) of the so-called snakebark maples, whose trunks display whitish, lengthwise striations. But Acer pensylvanicum ‘Erythrocladum’ takes the species to a whole new level, because once the weather turns cold, its branches turn a glowing salmon red—like A. palmatum ‘Sangokaku’ (if you know that plant), only better. The Arnold Arboretum has a strapping specimen near the greenhouses, and the first time I saw it, outlined against white snow and a deep blue January sky, I stood there gaping until I realized that my ears and toes were about to fall off.
In the wild, A. pensylvanicum is an understory plant that likes to grow on shady, northern slopes at elevations from 2,000 to 4,000 feet, which tells you what it needs in the garden: partial shade, coolness, regular moisture, and well-drained, humusy, slightly acidic soil. The chief difference between the plain species and ‘Erythrocladum’ is that the former is hardy to USDA Zone 3, whereas you’re pushing your luck if you try to grow ‘Erythrocladum’ in areas colder than Zone 5.
Companion planting isn’t much of an issue in midwinter, but, in my garden at least, ‘Erythrocladum’ retains its bright color well into early spring, when it pairs well with salmon-flowered Pulmonaria rubra ‘David Ward’; pale blue pulmonarias would be nice, too, as would white Lenten roses or the Sunset Group strain of Helleborus niger.
Because A. pensylvanicum ‘Erythrocladum’ is extremely difficult to propagate—it takes a skillful grafter to do it—sources are scarce, and you may even have to go on a waiting list. It’s worth it. The sight of those glowing branches takes the chill out of the bleakest February day. H
|Type of plant||deciduous tree/large shrub|
|Family||Aceraceae (maple family)|
|Habit||short-trunked with narrow, rounded crown|
|Leaves||3-lobed, 4-7 in. long and wide; fall color bright yellow|
|Bark||young branches marked by vertical whitish stripes; stems turn coral red after leaf fall|
|Rate of growth||slow|
|Hardiness||USDA Zones 5-8; Sunset Zones 3-9, 14-22, 32-41|
|Soil||moist, well-drained, acidic|
|Water needs||moderate, regular|
|Propagation||by grafting; difficult|
|Problems||verticillium wilt, leaf spot; relatively free from insect pests; thin bark is easily damaged|