We have been trying to grow a hedge in alkaline soil in Bowmanville to no avail for several years and would like some advice on what kind of plants do well as hedges in alkaline soil.
You could have your soil tested and try to adjust the pH level in it by adding compost and other recommended amendments but it would be much easier to find plants that actually require alkaline soil.
There are several plants suitable for hedging that that should do well in your area, which is Canadian hardiness Zone 6a, and in moist, well drained alkaline soil.
Toronto Master Gardeners has a gardening guide on its site which gives instructions on choosing, planting and maintaining evergreens suitable for hedging. The evergreens mentioned in this article which fall into the category you are looking for include: Eastern White Cedar, Juniper, Boxwood and Yews. Find the guide at:
Some more specific varieties of these and other suitable evergreens are: Green Velvet boxwood (Buxus ‘Green Velvet’); Eastern White Cedar (Thuga occidentalis); Euonymus fortunei ‘Emerald Gaiety’, ‘Silver Queen’ or ‘Emerald n Gold’; Mugo Pine (Pinus mugo)
Or, you could consider various deciduous shrubs such as Deutzia; Forsythia ; Mock oranges (Philadelphus spp.; Lilacs (Syringa spp.); Weigela; Spirea; Sea Buckthorn (Hippophae rhamnoides); Scarlet Elder (Sambucus pubens); Japanese Barberry (Berberis thunbergii); Daphne (Daphne x burkwoodii ‘Carol Mackie’); Dwarf Bush-Honeysuckle (Diervilla lonicera); Leatherwood (Dirca palustris)