Manitoba’s Ecoregions and What Gardeners Can Learn from Them

Manitoba’s Ecoregions and What Gardeners Can Learn from Them

By Linda Dietrick, Master Gardener

 

In 1997, Canada, the US, and Mexico collaborated to produce an ambitious project called the North American Environmental Atlas. This detailed map of North America defines what are called ecoregions, based on similarities of geography, geology, soils, hydrology, vegetation, wildlife, land use, and climate. The map is available in three versions, according to levels of detail. You can download each level of the map as a PDF here: https://www.epa.gov/eco-research/ecoregions-north-america.

Level I divides our continent into 15 broad ecoregions; Level II subdivides those into 52 ecoregions; and Level III further subdivides them into 182. Each of the subdivisions is assigned a number, name, and colour on the map. Here is a detail from the map showing most of our province and the ecoregions it is part of at Level III.

Map – North America Ecoregions – United States Environmental Protection Agency

 

 

Southern Manitoba is part of the Great Plains (9.0), the vast, tan-shaded swath that stretches all the way down to Mexico. More narrowly, it belongs to the Temperate Prairies (9.2), which reach from northern Alberta down into the corn belt in Iowa. Southwestern Manitoba sits in ecoregion 9.2.1, the Aspen Parkland and Northern Glaciated Plains, which curve around from Calgary to Edmonton through northern and eastern Saskatchewan and Manitoba, and then run south through the Dakotas to Sioux Falls, SD. Winnipeg sits in ecoregion 9.2.2, the Lake Manitoba and Lake Agassiz Plain, which runs from Lake Manitoba along the Red River valley to south of Fargo, ND. This last ecoregion corresponds to the original tallgrass prairie.

Designated by shades of green, northern Manitoba from Thompson south, together with southeastern Manitoba, belongs to ecoregion 5.0, the Northern Forests. Subregions include the Softwood Shield (5.1), Mixed Wood Shield (5.2), and the Boreal Plain (5.4). The Interlake and the Whiteshell both sit in 5.4.3, the Mid-Boreal Lowland and Interlake Plain. The southeast corner of the province, along with the Northwest Angle and Lake of the Woods, is placed in 5.2.2, the Northern Minnesota Wetlands.

What can we learn from this map?

Broadly speaking, it tells us who lives in areas that are ecologically similar to ours. This is different from the hardiness zone maps that help us decide if a plant is likely to survive in our gardens. Whether you use the Canadian hardiness map (https://planthardiness.gc.ca/) or the American one (https://planthardiness.ars.usda.gov/) or older versions thereof, the zones are mainly determined by temperature and climate. They can be deceptive because they create divisions that do not take other ecological factors into account. Also, the zone maps end at the respective national boundaries, as if these were natural boundaries, which of course they are not. It turns out that, based on the ecological characteristics of the lands we live and garden on, Manitobans have a lot in common with people in Alberta, Saskatchewan, Northwest Ontario, the Dakotas, and Minnesota.

In my imagination, I picture the original indigenous inhabitants travelling freely through these different ecoregions, obviously without regard to modern political boundaries. With a depth of knowledge far beyond my own, they would have sought out and relied on familiar plants and animals that they knew to be characteristic of each ecoregion. The vast herds of bison are long gone from the Great Plains, and much of this land area is now converted to agriculture and residential or commercial development. Yet the land is still home to characteristic populations of plants, insects, birds, and other living things that have been here for thousands of years.

Sourcing new, appropriate native plants

If like me you want to plant more native or indigenous plants so as to help preserve the diversity of life that has long been present in our part of North America, it makes sense to look beyond national and provincial boundaries and recognize common ecoregions.

True, our native plant nurseries usually insist that the seeds and plants they call indigenous should originate from within our provincial borders, and I can see how that might be a good rule of thumb for preserving local genotypes. But plants do not care about political borders. Why shouldn’t I adopt a plant from one of the broad ecoregions that my garden resides in, even if the plant has been designated native to another state or province and not Manitoba?

This seems like a good strategy if the plant in question is rare or likely to become rare, especially given climate change. For example, Culver’s root (Veronicastrum virginicum), while quite common in the US, is now rare in Manitoba and Ontario and completely extirpated (i.e. historically present but now gone) in North Dakota. See the Biota of North America Plant Atlas (https://BONAP.net/Napa/Genus/Traditional/State), which indicates the native ranges of indigenous plants.

Local native plant growers encourage us to grow Culver’s root in our gardens because of its rarity. Similarly, wild geranium (Geranium maculatum), though common in many US states, is rare in Manitoba and South Dakota and extirpated in North Dakota, according to BONAP. Large-leaved aster (Eurybia macrophylla) is likewise rare in Manitoba, though still common in Ontario and Minnesota.

 

 

 

Other plants could be called “nearby natives.” These include showy goldenrod (Solidago speciosa), not to be confused with grey goldenrod (S. nemoralis), which is also sometimes called showy, and the shade-tolerant zigzag goldenrod (S. flexicaulis). Both are good garden candidates because they do not spread by their roots. However, they are only considered native to Ontario and the Dakotas, not to Manitoba. Cardinal flower (Lobelia cardinalis), a moisture-loving species that is common in Ontario and Minnesota but not considered native here, is one of North America’s most beautiful wildflowers.

 

 

These nearby natives are arguably part of the vegetation of our local ecoregions and worth trying here. Of course, they are not available from any of the Manitoba native plant nurseries: Living Prairie Museum, Northern Wildscapes, Prairie Flora, Prairie Originals, Prairie Shore Botanicals, and Skinner Native Seeds. (See our guide at mgmanitoba.com/2025/01/08/sources-for-native-plants-and-seeds-in-manitoba/. An update is planned for March 2026). However, you may wish to try sourcing seeds or plants from native plant nurseries located outside Manitoba, but still in a shared ecological subregion.

Here are some options: ALCLA Native Plants (Carstairs, AB), Blazing Star Wildflower Seed (Aberdeen, SK), Northern Wildflowers (Sudbury, ON), Prairie Moon Nursery (Winona, Minnesota), and Wild About Flowers (Foothills, AB). All of these are easily found on the web and offer seeds for regional species. ALCLA and Wild About Flowers will also ship live plant plugs via Canada Post to Manitoba. Prairie Moon, a major American native plant nursery, does not ship plants to Canada due to the need for phytosanitary certification, but you can order from their extensive seed listing.

A key reason for growing indigenous plants is their ability to support insects and other pollinators, especially those with specialized relationships to certain plants. It is well known that goldenrods are larval hosts to specific butterflies and moths, as well as pollen sources for numerous native specialist bees. Cardinal flower is recognized as a valuable nectar source for hummingbirds. And in general, an abundance of floral resources of all kinds, extending throughout the growing season, helps to support native bees, butterflies, moths, and other insects, which in turn provide food for other creatures like birds. These are good reasons to adopt into our gardens indigenous plants from nearby provinces and states that share Manitoba’s ecoregions.

Additional Sources

Dietrick, Linda. “Plant Recommendations for Gardeners from Manitoba’s Native Plant Growers.” MMGA Newsletter, January 2025. www.mgmanitoba.com/2025/01/08/plant-recommendations-for-gardeners-from-manitobas-native-plant-growers/.

Holm, Heather. Pollinators of Native Plants. Pollination Press, 2014.

Manitoba Conservation Data Centre Plant List. www.gov.mb.ca/nrnd/fish-wildlife/cdc/pubs/plant_list_mbcdc_2024jan.pdf.