I live on Lawrence Ave W and just replaced my retaining wall. Soil is clay and is now 9’x13′ facing south. The contractors had left stones and debris and I have tried to remove as much of these. The front is 2′ high due to the wall now straight instead of a slope and the side is 10” x 16′ long. Can I just try to move the existing soil to fill in the gaps and level off and then add new earth on top of existing soil or go with only mulch. I only have 2 hick’s yews and some. I had a border of Heartleaf Bergenia but most were damaged during the construction. Last few years I had nd loved Ruby Stone Coneflowers but they took the whole area over. I am looking for suggestion on some lower maintenance small shrubs as a border (not boxwood but maybe some low round or dwarf euonymus. Simple but something all year round but not too spreading due to the small space.
Thank you for your question. You have mentioned that you have clay soil and a southern exposure. This is an ideal time for you to amend your soil with some organic matter such as peat moss or compost. You can add these amendments to the soil surface. Over time, the clay beneath will slowly work its way down and start loosening up the clay. Adding mulch once any new plantings are put in would help to retain moisture and keep weeds down.
You may wish to take a look at our Toronto Master Gardeners (TMG) Gardening Guide: Using Mulch in your organic garden for specifics on types, benefits, and application tips for using mulch.
Considerations for lower maintenance small shrubs would include minimal spreading (as you have mentioned) and something with a smaller root system.
For some good choices you might find “Evergreens Suitable for Hedging: A Toronto Master Gardeners Guide”, which recommends several smaller evergreen varieties you might want to consider (not just for hedging). As well, see our comprehensive “Ornamental Shrubs for Various Light conditions: A Toronto Master Gardeners Guide”, which also provides many shrub suggestions (not specifically evergreens, though), as well as information about care, maintenance and dwarf varieties.
In addition, one of our previous posts included the following recommendations for smaller garden areas:
Dwarf Oak Leaf Hydrangea, (Hydrangea quercifolia ‘Sike’s Dwarf’) has a height of just 2-3 feet and a spread of 3 to 4 feet at maturity. It blooms in late spring with white, conical flowers that fade to pink. The leaves are deep green which turn to shades of maroon in the fall.
Dwarf Ninebark (Physocarpus opulifolius Tiny Wine) is a new, smaller ninebark with a height and spread of 3-4 feet. The leaves are a deep maroon and are a great contrast for the pink flowers. Bloom time is mid-spring.
Dwarf Fothergilla (Fothergilla x intermedia ‘Mount Airy’) is a beautiful small shrub with a height and spread of 4 feet and a spread of 3 feet. It is known for its profuse white spring flowers, good summer foliage, excellent fall colour and consistently upright habit.
All of these above shrubs are considered low maintenance and while two of them may have a mature spread of a little more than 3 feet, occasional pruning should keep them to your desired size.
You may wish to take a look at our Toronto Master Gardener Gardening Guide on Drought Tolerant Perennials as another options for replanting your garden.