Although perennials are important to me, the backbone of my garden consists of trees and shrubs. Each spring, I plant more than a hundred of them, generally about 20 or so at one go, choosing plants that are hardy to Zone 2 and drought-tolerant, and provide food or habitat for birds and as much four-season ornamental interest as possible. About 20 per cent of what I plant are evergreens, chosen for density, wind protection and winter landscape value. The seedling Scots pines planted in 1980 now provide privacy, snow catchment and songbird habitat. Their informal groupings almost surround my property. The following trees and shrubs have proven indispensable: Manitoba maple, green ash, bur oak, nannyberry, lilac, cotoneaster, pin cherry, chokecherry, sea buckthorn and Scots pine.
I have a soft spot for colourful foliage: gold is represented by golden elder, golden mock orange and 'Depressa Aurea' juniper; purple by smoke bush, purpleleaf sand cherry, 'Shubert' chokecherry and barberry; and silver-blue by 'Zempin' wolf willow (also known as silverberry), sea buckthorn, silver buffaloberry and 'Globosa' blue spruce. These complement perennials, such as Adam's needle (Yucca glauca), and ornamental grasses including blue fescue, blue oatgrass, blue lyme grass and Skinner's golden bromegrass.
Once the bones of my garden were in place, I began trying odd and unusual species and cultivars of trees and shrubs, relying heavily on their provenance for clues as to whether they'd survive. For example, the white pine (Pinus strobus) I'd purchased from a nursery promptly died in winter, but a seedling dug up by a friend from a ditch along the highway near Thunder Bay, close to its most northerly and western range, has flourished. Another friend brought me a sugar maple (Acer saccharum) seedling from west of Ottawa. It, too, is thriving. A Russian mulberry (Morus alba var. tatarica) has made it through three winters with a struggle, and I'm now trying a number of the newly introduced barberry (Berberis spp.) cultivars. Sheltered directly behind the perennial borders, where they receive regular watering, 'Delta' hackberry (Celtis occidentalis 'Delta') and 'Prairie Cascade' weeping willow (Salix 'Prairie Cascade') have also done very well.
Mulching for success
Mulching is key. Each spring, for the past decade, I've ordered a semi-truckload of post peelings—the stringy pieces of bark and wood removed by a fence post mill. This is enough to mulch new plantings and top up old, decaying mulch. A 10-centimetre-deep layer of post peelings stays effective for three to four years.
Not all my plantings have been successful. With winter dieback, a 12-year-old Manchurian walnut (Juglans mandshurica) has attained a height of just 45 centimetres, and the bristlecone pine (Pinus aristata) and Ponderosa pine (P. ponderosa) looked so sorrowful that I took them out.
A few years ago, I began to sense what the last, uncultivated part of the pasture might look like. In the spring of 2002, I developed a stone circle on the highest knoll, surrounded by two larger circles containing seedling pine, hawthorn and wolf willow. This past spring I planted a ribbon of Siberian pear trees and additional groves of larch and flowering crabapples, as well as mixed shrub borders. I've put in a double row of Manitoba maples in sweeping curves along the inside of the shelter belt, so that someday, I'll be able to walk the dogs, Ben and Eric, in the shade.