Typical flower gardens are planted only to look pretty. They’re filled with the latest plants from other parts of the world, or ones that have been bred for certain flower characteristics (like flower colour or size). For almost 20 years, I had a purely ornamental garden. I bought all the newest plants, especially ones with variegated or coloured leaves. I never considered whether the plants in my garden would feed pollinators or birds. Sadly, many of my introduced plants have little value to native wildlife.
Food webs depend on native plants
In Bringing Nature Home, entomologist Douglas Tallamy demonstrates that the non-native plants that fill our yards have created landscapes devoid of food for butterflies, moths, or other plant-eating insects. In his suburban yard, Tallamy observed many insects on native plants, but hardly any on non-native plants. The research and conclusions that followed have begun to change the gardening world.
Tallamy explains that native insects have evolved with native plants; gradually the insects were able to eat certain plants and tolerate their unique chemical compositions. Eventually, many native insects could only eat particular native plants. For example, Monarch butterfly caterpillars can only eat milkweed. By planting our yards primarily with non-native plants and trees, we’ve eliminated the essential plant food that these native insects depend on. In turn, there’s no food for insect-eating creatures, like song birds who must feed their baby birds a diet of soft, protein-rich bugs. If we want to help pollinators, birds, and other wildlife, we must reintroduce native plants to our gardens.
For an introduction to Tallamy and his influential work, watch this EcoBeneficial video interview with him. You can also find longer videos of his lectures on YouTube. Bringing Nature Home, as well as Tallamy’s beautiful, and easier-to-read, coffee table book The Living Landscape, are available at the Ottawa Public Library.
A recent study of chickadees in Washington, D.C., Ecologists Have this Simple Request to Homeowners — Plant Native, confirms Tallamy’s conclusion and encourages us to plant our yards with 70% native plants.
What are native plants?
I am loosely defining native plants as ones that grew here before European colonization; the plants that native insects co-evolved with over thousands of years. ‘Non-native’ plants were brought here from somewhere else, such as another continent or another part of North America. I sometimes call non-native plants ‘introduced’ plants, and native plants ‘local’ ones.
Which plants are native to Ottawa?
I am in the process of learning which plants are not only native to Ontario, but are also native to the Ottawa area. For this purpose, I highly recommend the Wildflowers: what’s native? blog post by the Wild Pollinator Partnership listing resources on native plants in our region. Of these resources, my favourite one is Appendix A — Vascular Plants of the City of Ottawa; non-native plants are clearly indicated by a # symbol in the narrow, second column. Here, I can quickly search for the name on the page and check for the symbol.
When I first started growing native plants, I thought that anything from North America would do. I ordered seeds from Ontario, Alberta, Manitoba, and even the United States.
I later learned that it is best to use plants that are local ecotypes, or variants, of native plants. A native plant grown from local seed has adapted to the exact conditions of the Ottawa area. It will may look slightly different from the same type of plant from Southwestern Ontario, it may be slightly hardier, or it may bloom a bit earlier than it distant cousins. In order to preserve local ecotypes, we should plant local plants and seeds.
Beaux Arbres Native Plant nursery specifies when seeds for their plants have been collected from a parent plant in the Ottawa Valley. The plants sold at the annual Fletcher Wildlife Garden Native Plant Sale are all grown from local seed.
I am in the process of backtracking to figure out the provenance of my native plants, to determine which ones are actually local ecotypes. When I share seeds and plants with others, I want to be clear when their kin hails from another area.