I am planning to plant a few ornamental grasses in between rocks on the shady side of the garden. The soil is sandy and I am located in Toronto.
Thank you for contacting the Toronto Master Gardeners.
The majority of ornamental grasses require full sun and well draining soil. However, there are a few variety of grasses which will tolerate part shade and will not become overly aggressive.
You mention that you would like to plant on the shady side of your garden. You didn’t mention if the planting area is in total shade or in partial shade. Total shade means that the shade lasts all day long. Very little, if any, direct sunlight hits the plant at any time of the day. Partial shade is approximately 2-4 hours of sun per day in a given location. Plants in partial shade may receive direct sun throughout the day for a few hours with at least half the day spent in shade.
When it comes to selecting hardy plants for your garden, choosing the correct hardiness zone is important. The following excerpt is from one of our earlier posts titled Plant Hardiness Zones.
“When selecting plants for your garden, choose those rated for more hardy zones, to maximize chances of survival. For example, if you have a plant that is hardy to Zone 5 and you live in Zone 6, the plant should be happy in your garden (as long as it receives appropriate care – e.g., sun exposure, soil type). Toronto is generally considered a zone 6. It is important to be aware that, in some pockets of the GTA, the zones may be higher or lower. For example, if your garden is closer to Lake Ontario, it may be in Zone 6b or even 7. Further from the lake or in a more exposed area, your garden could be in Zone 5a or 5b. (in terms of Canadian Zones)”
Five Ornamental Grasses for Shade is an excellent article by Lorraine Flanigan for Garden Making, which lists hardiness zones and mature sizes of the various grasses. The University of Illinois also has an excellent list on shade tolerant ornamental grasses.