5 January 2017
Mahonias for Winter Colour
Perhaps the most striking plant in my garden at this time of year is a Mahonia, which I planted about twelve years ago. The dark, glossy leaves show off the stunning greeny-yellow flowers, and it is flowering when there isn't much else to admire.
There are a number of varieties of Mahonia, with M. x media ‘Charity’ probably the best known of them. This will grow to a substantial (and very prickly) shrub, 2m (6½ft) square, given space and time.
The earliest to bloom is M. x media ‘Lionel Fortescue’ which will draw bees to its upright primrose-yellow flowers that have a wonderful lily-of-the-valley perfume.
Yet another cultivar of the media hybrids is ‘Winter Sun’ which is smaller than either ‘Charity’ or ‘Lionel Fortescue’ and also has deliciously scented flowers. Winter Sun is very hardy, tolerating both extreme cold and shade, although it has a tendency to become rather lanky and needs pruning to hold a good shape.
Mahonia x media is the result of a cross between M. lomariifolia and M. japonica and incorporates the virtues of both its parents. The other parent of Mahonia x media – M. lomariifolia – comes from Burma and Yunnan in China where it can become a really big shrub, reaching 12m (40ft) tall. It is more tender than M. japonica, not hardy below -10°C and unhappy in any windy, exposed spot in winter.
Mahonias get their name from an Irishman, Bernard McMahon, who emigrated to Philadelphia in the 18th century and set up a nursery which became a famous horticultural meeting place. The American mahonias are generally shorter and more spreading than the taller Asiatic ones, and do better in sunny sites with well-drained soil, whereas the Asian ones like some shade and, as cope happily with heavy soil. However most mahonias will adapt perfectly well to wherever you place them and M. aquifolium in particular is remarkably hardy and adaptable. It will also make very good ground cover, albeit rather prickly.
As I have said, most mahonias will grow in almost any situation and soil but there is no doubt the Asiatic ones do have a tendency to become defoliated, especially if grown in shade. The answer is to prune them back as soon as they have finished flowering, to encourage healthy new growth that will carry flowers next year and to keep them compact.
Pruning mahonias is straightforward but may need to be a bit drastic if you are dealing with older specimens. Remove the largest and barest stems to a couple of feet above the ground and they should resprout from below the cut point and the shrub will become denser.
My mahonia was getting too tall, with long bare stems, so I have been removing two per year for the last couple of years, which has encouraged new growth at the base of the plant. In a couple of years time I will have a shorter but vigorous shrub to admire.
After any drastic pruning, it’s a good idea to clear around the base of the plant and mulch thickly with garden compost or well-rotted manure to preserve moisture and nourish the plant.
Why not consider a Mahonia for your garden - they are easy to look after, relatively inexpensive and provide you with winter colour.