Long before European settlers arrived here, tallgrass prairies covered over 400,000 square miles of North America. Minnesota lay on the northeast corner of the prairie that stretched from the Rockies to east of the Mississippi, from Canada to Texas. The tallgrass prairie formed during an extremely warm and dry period 9,000 years ago. It was a mix of flowers and grasses that adapted to the hot, dry conditions by developing an extensive root system running as deep as 10 to 15 feet. With 75-80 percent of their biomass underground, the prairie plants were also well adapted to survive prairie fires.
The prairie was a diverse and complex ecosystem surpassed only by the Amazon rainforest. It was an ecosystem too wet for a desert to form and too dry for a healthy forest. It thrived through extreme heat and drought, and survived frigid temperatures and winds. Forty-60 species of grasses made up 80 percent of the prairie, with nearly 300 species of forbs and flowers making up the other 20 percent.
At one time the prairie provided sustenance for 30-60 million buffalo along with elk, deer and antelopes. Prairies provided a habitat for large mammals including wolves and grizzly bears, and small mammals like gophers and innumerable birds. For centuries the prairie sustained Native Americans whose primary source of protein was buffalo. They also reaped prairie turnips, rose hips and grass seeds from the prairie. In the 20th Century the prairie provided hay for cattle, milkweed pods were eaten during the droughts of the ‘30s and milkweed seeds filled life preservers in World War II.
In the mid-1800s the fertility of the prairie soil was discovered; it was deep and rich in organic matter due to the decomposition of the roots underground. Acres of prairie were cleared and planted with wheat, corn and other crops. Today only 1 percent of the 170 million acres of tall grass prairie remains, making it one of the most endangered ecosystems in the world. Efforts are being made to restore and recreate prairies in Minnesota. A prairie has been restored at North Mississippi Regional Park and efforts are being made to recreate one at the Victory Prairie site. An opportunity to experience 80 acres of prairie exists at the Jeffers Petroglyph site near Comfrey, Minnesota — 47 acres are for recreation but 33 acres are part of our remaining native prairie.
We can help restore our native ecosystem on a smaller scale by planting prairies in our own backyards. Planting a prairie provides a habitat for native birds, butterflies and bees, and prairie plants are perfectly adapted to thrive in our hot, dry summers and cold, snowy winters. Prairie plants grow best in full sun in open spaces with a minimum of trees. If you have this space in your yard you can recreate a prairie.
The first step is to remove all existing vegetation to reduce competition for the seed or plants you want to see in your prairie. There are three options to for doing this depending on the amount of effort you want to make, your patience and your tolerance of chemicals.
- Cover your space with a sheet of dark plastic or plywood for two months and then till to a depth of 12 inches.
- Till the soil to a depth of 12 inches every two weeks for entire growing season. This will turn the weed seeds under the soil and then turn germinated weeds under until they are all eliminated.
- Spray a non-selective herbicide containing glyphosate, such as Roundup™. Wait two weeks and till to 12 inches.
Once your site is clear amend the soil with compost or manure. You can plant either seeds or plants. Each has its advantages and disadvantages. Seeds are more economical but can take 2 to 5 years to reach full size. Plants are more expensive but reach maturity sooner. Some may flower in the first season. Some native prairie plant seeds have a low germination rate, in which case you might be better off to buy a plant. You can control the placement of your plants and can plant from spring through fall, while seeds should be broadcast broadly between May 20 and June 20 (or mid-October through freezing for dormant seeding). You will have a more natural looking prairie with if you plant seeds, but beware of prairie seed mixes that come in a tin or tub– not all of the seeds may be hardy to our zone. If you use seeds make sure to have good seed-to-soil contact. All though it is not necessary, watering can help – keeping the seeds from blowing away.
Maintenance to control weeds is critical in the first few years of a prairie. For large prairies the best way to do this is with a controlled burn in April or May. A controlled burn promotes native plant growth by keeping down trees and weeds, and recycling nutrients. In very large established prairies, sites are burned one section per year, leaving some food and shelter for birds and other small animals. Sections of the prairie at North Mississippi Regional Park are being burned right now – you may be able to smell it if you get close enough. Although the Victory Prairie was planted with native prairie seeds, it is the lack of maintenance that has allowed the weeds to take over and prevents it from becoming a mature prairie.
Burning is obviously not recommended for home prairies. Smaller prairies can be maintained by one of two methods. If it is a small enough area it can be hand weeded, but if it has been planted by seed it is sometimes hard to distinguish between the prairie plants and the weeds, especially in the first few years. Another method is to mow to 4-8 inches high and remove the clippings for the first few years. Weeds grow quicker than prairie plants, so you can cut them back so they don’t go to seed. Most will not come back next year.