Winter Flowers: Mahonias
December can be a bleak month for flowers unless you count the odd, brave snowdrop or a precocious witch hazel. The last of autumn leaves have fallen, and the late-flowering asters have gone to seed. While it is true that the bright red hollies can wake up our gray senses, they lack the sensual power of flowers, a strong reason for the magic of gardening. Only do the days become perceptibly longer in late January can we anticipate winter flowers even if they lack the spring pyrotechnics. Often the wait is rewarding for winter flowers can be intensely scented.
Why do these plants expend energy flowering when odds are stacked against them? Winter flowers do not have to vie for pollinators as they would have if spring and summer were their seasons. They're savvy to recognize that those warm winter spells will revive any hibernating insects needing sustenance for the next cold spell. I am always taken surprise at seeing bees and various members of Hymenoptera (bees) and Diptera (flies) at what seem paltry options in winter. Somehow the plants do succeed when mature, ripe fruit take the flowers' place later.
Before Christmas, I can always count mahonias to commence the winter flowering season. Their sprays of yellow flowers glow bright and incandescent in the weak winter light, luring us as much as those hapless pollinators. Sweet and heavy like honey, the mahonia's perfume can cut through the chill like a scythe in a wheat field. It is faintly suggestive of lily of the valley, but more potent in its intensity. The best mahonia for fragrance remains Mahonia japonica, a species curiously not found in the wild.
Lax and wide spreading in habit (6 ft tall by 5-7 ft wide), Mahonia japonica can be hard to accommodate in small gardens. And despite being highly scented, the flowers of M. japonica may lack the showiness factor people seek in winter flowering shrubs. Those willing to accept less fragrant, but showier flowers can look towards Mahonia x media.
A hybrid of M. oiwakensis subsp. lomariifolia (syn. M. lomariifolia) and M. japonica, Mahonia x media originated in the batch of open-pollinated seedlings in northern Ireland. One seedling was grown at Savill Gardens, England, where it was named 'Charity' (its siblings were respectively named 'Hope' and 'Faith'). Breeders expanded the selections, which vary in flowering times and mature sizes. Generally Mahonia x media tend to form taller, if not tighter, statuesque shrubs than M. japonica. They are surprisingly architectural as their leaves have this precise zig-zag pattern somewhat tiered on the stems.
Some people are highly dismissive of mahonias' ranginess over time. Pruning the stems hard to 1' to 2' will encourage new shoots to develop - it is advisable to cut in spring for the plant to heal and regenerate rather than autumn or winter. Others might view the leggy stems as an opportunity to underplant with interesting shrubs or perennials to conceal them.
Mahonias do best in mild winter regions. They require protection from winter winds, which can scorch and tatter their beautiful foliage. Although the damage appears cosmetic, the effect is rather distracting for the evergreen leaves can be long-lived. In fact, open and sunny exposed locations are not ideal for mahonias, which tend to be understory shrubs in the wild. I often see robust plants in northern exposures, and in dry shade where other plants would fail. It is a common sight in London to see mahonias somehow flourishing in those dark corners, lurking furtively until their flowers appear, awakening the bleary landscape.