What are Native Plants?
Plants are considered native, indigenous, or endemic to a region if they originated and are naturally occurring in that region. Many “wild” plants that we think of as native species were actually introduced during European settlement to North America. Plants that are native to Southern Ontario evolved here and have adapted to the regional climate, soils and wildlife.
Most native plants that are native to Southern Ontario are appropriate for planting in the Toronto area. However, Southern Ontario is a large geographic area that varies in environmental conditions. If possible, give preference to plant materials produced from seed collected closest to your planting site. This will ensure that the plants you are using will be best adapted to local environmental conditions. For example, planting a maple tree that came from a seed indigenous to the Toronto area will do better in Toronto than a similar maple that evolved and adapted to conditions in Ottawa or Windsor or Owen Sound.
Using local genetic stock is particularly important if your property is close to one of Toronto’s parks or ravines. This is because there will be exchanges of genetic material from your yard into these natural areas. By using native species from local stock you will ensure that Toronto’s native plants will remain genetically adapted to local conditions.
Contributing to Local Ecosystems
The loss of habitat as a result of rapid urbanization in Southern Ontario is affecting ecosystem health and reducing the diversity of native plants and wildlife in natural areas. In addition to the benefits of lower cost and maintenance, using native plants can help sustain local ecosystems. Ecosystems are communities of plants and animals including the physical environment they inhabit. Plant and animal communities are dependent on many environmental factors including sunlight, soil, water, and organic material. Examples of communities found in Toronto are forest, woodland, savannah, prairie, and marsh.
Learning From Nature
When considering the integration of native plants into your garden, you may wish to simply add some native wildflowers to your existing beds with or without a particular goal in mind such as adding colour or attracting butterflies. Alternatively, you may wish to incorporate a native plant community into your yard. Plant communities that have evolved together should require no maintenance, other than protection from urban pressures (i.e. trampling, digging, dumping and non-native weeds).
The different plants in these communities have adapted to local soil conditions and climate, as well as how other plants in their community may affect their environment. For example, native trees tend to leaf out late in the spring, allowing native spring wildflowers enough time to flower before they are shaded over. A non-native tree, such as a Norway Maple, leafs out early and has a very dense canopy, which shades out most plants from its understorey, this in turn often leads to problems with soil erosion. Native wildflowers are perennial or self-seeding, which means you will not have to replace them every year. Woodland species are adapted to pushing through leaf litter while benefiting from its’ insulating, moisture retaining and fertilizing properties. This means that you will save time, money and effort by not having to rake leaves, water or fertilize your naturalized garden.
Examples of native plant communities in Toronto include the globally rare Black Oak Tallgrass Savannah, found in the High Park area or Mixed Hardwood forest communities that include a variety of maples and nut trees. The best way to find out about native plant communities is to go out and see them. Contact a local naturalist or stewardship group for support and advice.
Native Plant List for Toronto
The preceding list of suggested native plants is provided for the Toronto Region. Because ecosystems are dependent on environmental conditions such as moisture and light, the species listed in each square of the table represents a plant community. Choosing plants from the same community will help them to thrive. Most of these species are available at local nurseries, however you may need to contact several outlets to find a specific plant. Asking for less common native species may help to increase their availability in the horticultural trade.
Recommendations are given for a mix of trees, shrubs and herbaceous plants according to their preference for soil and sunlight conditions. Dry soils include sandy and gravelly soils that drain readily. Average soils are well drained silts or clays that may have standing water for short periods after a hard rain. Moist soils include those with high clay content, they will be moist through the growing season and may experience extended periods of standing water. Sun exposure can be estimated by the number of hours your property receives direct sunlight ranging from a minimum of 6 hours for full sun, 2 to 6 hours for part-sun and less than 2 hours for full shade.
Match your backyard conditions to the species’ preferences to obtain the best planting results. You should be able to increase the list of species that are appropriate by reviewing gardening books and nursery catalogues. There is some overlap for the species given since some species are adapted to a range of conditions.
Sources of Native Plants
The origin of native plants is important since plants are adapted to specific site conditions. It is also important that the method of seed collection used maintains a high genetic diversity and prevents wild populations from being depleted. A plant’s genetic diversity is important to its ability to adapt to environmental change. Obtaining native plants from environmental organizations is the best way to ensure that you are obtaining plants from a reliable source. Some volunteer groups and other associations in Toronto sell native plants to the public at designated plant sales. Some nurseries specialize in native plants. However, most commercial nurseries now include some native species in their inventory.
Buying Native Plants from Commercial Nurseries
Finding appropriate native plants can be challenging since most commercial nurseries carry cultivated varieties of native species. Since they are often reproduced from cuttings in large quantities from one individual plant, cultivated varieties have low genetic diversity. Ask staff about the source of plant material and use Scientific (Latin) names to make sure you receive true native varieties. Give preference to plants that have been propagated from seed that was collected closest to your planting site. Be cautious about species labelled as Red Maple, White Birch, Snowberry, Highbush Cranberry and Pussy Willow since they are often substituted with non-native invasive varieties. More information on invasive plants can be found here. Some woodland plants including ferns and trilliums are very difficult to grow in large quantities, therefore the source should be questioned to ensure they were not dug from the wild.