My dog has done his business and killed the grass, so I would like to replace it with ground cover, and 2-3 types of plants of different heights. It would be nice to have flowering, evergreen and/or edible plants, maybe a berry bush. The area is mostly shaded, moderately moist with a high pH of at least 8.0 (off the scale blue), and I have read that the dog urine leads to a very high Nitrogen content. The plants should not have an overly aggressive root system as it is close to both my and my neighbour’s front porch. The area is about 3′ wide by about 6′ long out from the house. The tallest plants could be in the range of 1′ up to 4′ tall closest to the porch. Note the spelling of my name in my email address (ii after the t is correct). Thanks!
Thank you for contacting the Toronto Master Gardeners. As you describe, dog urine can be toxic to grass and other plant material. Urine contains urea, a form of nitrogen. Plants need nitrogen but when applied in a concentrated amount it can kill them. This article from the University of Wisconsin provides a good explanation Lawns and Dogs. In planning a garden for this area, it may be prudent to consider whether or not your dog will continue to urinate in this spot and kill the plants. Watering the soil well can help to dilute dog urine and mitigate some of the damage but if this will be an ongoing issue you will need to plan around it. For example, a raised bed would elevate plants out of reach of the dog. Alternatively, an arrangement of pots / containers on a bed of bark mulch or stones also raises the plants out of harms way. Both of these options mean that the soil alkalinity would no longer be a concern as you would add fresh soil to the raised bed or container. Raised beds or containers would also be more sanitary options for edible plants.
Most soil in Southern Ontario is neutral to alkaline and many plants are adaptable so you will have lots to choose from. This gardening blog lists many plants, shrubs and trees that are suited to alkaline soil Plant list. Landscape Ontario has a great list of plants for shade here and you may want to cross reference these two lists to identify plants you’d like. For example, Columbine (Aquilegia spp.) and hosta are on both lists and would be suitable. Talking to your neighbours can also be helpful to find out what grows well in shady spots in their gardens, which likely have similar soil. Your local plant nursery staff can also be helpful. Landscape Ontario can provide a list of Nurseries near your location Nursery search. The Halton Master Gardeners has an excellent resource with garden design ideas for small spaces, including plant recommendations for shade and sun as well as listing plant heights Halton Master Gardeners.
Best of luck with your new gardening space!