The horticultural term ‘broadleaf evergreen’ refers to a group of plants that don’t have needles like conifers, and keep their foliage through the winter months. Rhododendrons, boxwood, pyracantha and holly are well-known examples in our landscapes of broadleaf evergreens.
Although we can grow a number of these plants in the Okanagan there are some restrictions. Generally they like to be situated out of the wind, particularly in the winter, because a bitterly cold, drying wind will not only freeze the foliage, but will also suck the moisture out. This results in a most unhealthy appearance in the spring, commonly known as “winter burn.” Some, like the rhododendron and pieris, need acid soils and shady locations to really do well in the valley.
Like the conifers, the broadleafs are an important group of plants in our gardens. The texture of their foliage and the structure of the plants provide a year-round effect, giving interest in the winter landscape when perennials have died back or deciduous trees and shrubs are without leaves.
One broadleaf evergreen that has made the transition from native to landscape plant is Mahonia aquifolium, the Oregon Grape. This plant can be found in natural areas in all but the very driest areas throughout the Pacific Northwest. The foliage is reddish bronze when unfurling in spring and their lustrous dark-green leaves in summer always look good, although the spiny tips don’t invite close observation. Winter sees some of the foliage turning to an attractive dull purple.
In April the ends of the branches erupt with bright yellow blooms that are slightly fragrant, followed a few months later by dark blue-black fruit that look like small cluster of grapes, hence the common name Oregon Grape, or Grapeholly. These berries are very tart, so the birds will leave them alone, although native peoples used them to make a jelly to go with their meats.
Like many of our native plants Mahonia aquifolium is quite variable. It can grow up to nearly three metres tall in the garden, but there are also forms that stay quite shrubby and low, growing only to one metre high. The shrub spreads by stolons; horizontal stems just under the ground that root at the tips, and can form large colonies over time if left unattended.
In the Okanagan garden mahonia is a valued shrub if only for the fact that it is a broadleaf evergreen that stands up well to our cold winters, and can be planted almost anywhere. It will tolerate sun or shade, and if you amend dry, sandy soils with some organic matter, and pay attention to its water requirements in the first growing season, it will thrive happily with little care in subsequent years.
Two alternatives to M. aquifolium that can be useful as lower growing shrubs are Mahonia nervosa, a low (30-50 cm.) suckering form that is native to the Cascade Mountains and Mahonia repens, growing only to 25 cm. tall with duller green leaves.
With Christmas decorating season almost upon us Oregon Grape is, of course, very useful as an option to the traditional holly. Use it in the same situations that you would use cut holly stems.

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