I have a wide hill (40 feet) in my backyard that’s about 40 degrees. I want to have a garden on it, but need to make sure the maintenance is low. I’m debating whether to terrace it or not. Since it’s very expensive to build a retaining wall, I wonder how manageable it is to garden on a 40 degree hill without terraces. I’m looking to gather some ideas so that I can assess the future maintenance, and to decide whether it’s worth to invest on a retaining wall.
I was just speaking to my niece who has a terraced back garden and she said that while it was expensive to have the space terraced and landscaped it is definitely worth it to her. Each terrace is easy to manage because it’s flat and makes gardening a lot easier.
However, there are many different options for planting a sloping garden. You could plant a rock garden using alpine plants and drought tolerant ornamental grasses. Or, you could plant a variety of different groundcovers. Most groundcovers are built to sprawl and cover exposed soil, which helps these plants stay put on a slope. Allowing these plants to take over will help reduce the amount of runoff, and gives a sloped garden a more finished look. Try tough groundcovers like ajuga, hens and chicks and thyme for delicate texture and solid soil stabilizers.
The most effective way to plan a low maintenance landscape, with or without a terraced wall, is to choose plants adapted to the climate of your gardens. Using native plants you can create a thriving, colourful hillside garden that will also attract pollinators including bees, butterflies and birds
The City of Guelph has a list of things to consider when planning a slope garden which covers such considerations as erosion control, plant selection and location and irrigation. It also has lists of plants appropriate for sunny and shady locations. For sunny areas this includes creeping phlox, lavender, bee balm and day lilies. For shade: fragrant sumac, bush berry, Solomon’s seal, heuchera, hosta and Hakone grass. https://guelph.ca/living/house-and-home/lawn-and-garden/sample-garden-designs/slope-gardens/
The following sites from the University of California’s Master Gardener program have a lot of good information on gardening on a slope or hillside including erosion control, plant selection and location and irrigation. Note that the plants listed here may not be suitable for our climate.
The following websites are excellent resources for information on Native Plants.
https://can-plant.ca (formerly the Evergreen Native Plant Database)
https://www.nanps.org (North American Native Plant Society)