Growing native plants is a great way to help restore habitat for our essential insect populations. It also contributes to preserving the purity of our water sources and to protecting populations of birds and animals, and maintains or improves the beauty of nature all around us.
There are over 400 species of native bees in Minnesota whose numbers are drastically decreasing due to habitat loss, disease, overuse of pesticides, and climate change. Native bees are essential. For example, orchard mason bees are highly efficient pollinators. They can even work in the rain and cold when honeybees take the day off. Fewer than 300 female mason bees can pollinate an acre of apple orchard. Native bees are our backup plan if non-native honeybees are not available to do the job of pollinating our plants. Conservation groups and Master Gardeners throughout Minnesota are encouraging the planting of truly native species to provide pollen, nectar, and shelter to our native bees.
So how do we, as homeowners, help our native bees in Minnesota? The answer: native wildflowers. I have looked at products labelled “wildflower mixes” and unfortunately discovered that these mixes often contain seeds that are not native to Minnesota or even to the United States. They may include varieties that are annuals, not perennials, in our Minnesota climate. Worse yet, they may contain varieties considered invasive weeds. For example, one nationally known seed company has a “Wildflower Perennial Mix” composed of "wild flowers” in the following categories:
Truly native perennials that support our local pollinators:
Native perennial that can become aggressive and may crowd out other more desirable species:
Non-native perennials that may not serve the needs of local pollinators and may become weeds:
Annuals, native or non-native, that might bloom the first year and never return in later years:
Perennials that are not native to Minnesota but are North American natives. Nevertheless, they are attractive and beneficial for our native pollinators:
Why aren’t there more, true wildflowers in many commercial mixes? Growing and harvesting native seeds is often labor intensive. Seed heads often must be picked by hand during that short time when the seeds are ripe but before seed pods open and scatter the seed. Cleaning and removal of chaff is often difficult. And time consuming. It may require special equipment to get the best seed purity. Therefore, true native species wildflower mixes with a high number of actual seeds can be expensive.
Studies have shown that a sizable number of the "wildflower” mixes contain undesirable, weedy, or even invasive species. Many contain filler or fluff to bulk up the package. Many nationally sold mixes try a “one size fits all” approach. The buyer might end up with plants that originate hundreds or even thousands of miles away (European or Asian wildflowers are usually not native to North America).
Some seed companies advertise their wildflower mixes as low maintenance. This is not true for real wildflowers. Ground preparation can be very labor intensive. Herbicides or tilling more than once are needed to remove common weeds, persistent sprouting, or invasive plants. Even with careful planting, true wildflower gardens are slow to establish. Continued maintenance of the planting is needed to remove weedy or invasive species.
Do not expect true wildflower seeds planted in the spring to result in a beautiful garden that summer, since many wildflowers will not sprout until they have overwintered. Most of our native wildflower seeds need a cold-wet period, called stratification, before the seeds break dormancy and sprout. This breaking of dormancy takes place naturally after seeds are exposed to our winter. This process can be simulated by placing the seeds in a damp growing medium for a few months in the refrigerator (the number of days needed varies by species). Google the species name and “stratification” for more information. Common wildflower mixes from big box stores often lack directions for fall sowing or stratification.
Do plant native wildflowers for our pollinators. Start slow or consult an expert for help. Do your research before you start. Consider buying wildflower plants to begin with. Some vendors may be found at our local farmer’s markets.
In Minnesota, native plant and seed suppliers and landscapers can be found at the Minnesota Department of Natural Resources website. Most provide valuable information about starting your pollinator garden.