April 21, 2025 The Rain Gardens on Grand Avenue We are thrilled to share the progress and success of the Grand Avenue Rain Garden Project, made possible through the collaboration between our Natural Shore Team and the Minneapolis Department of Public Works, Surface Waters, and Sewers. This green stormwater management initiative is working to reduce stormwater volume, improve water quality, provide essential habitat for pollinators, and enhance the urban landscape through the use of rain gardens. Grand Goals Grand Avenue is a vibrant and bustling Minneapolis street, known for its historic charm, lively commercial scene, and residential appeal. It’s home to a mix of local businesses, cozy cafes, inviting restaurants, and charming homes. In 2022-23, the City created nearly 200 rain gardens along Grand Avenue. One main goal of the project was to establish a mix of native prairie and wetland plants in shallow depressions. This native plant cover would then hold soil in place, create a valuable linear corridor for pollinators, and add to the beauty and appeal of the neighborhood. A Challenging Start An excavation contractor originally seeded the gardens with a native prairie mix, but this effort failed. Unfortunately, invasive weeds took over the gardens and became an eyesore. The City and community groups came together and determined that a total reset of the gardens was necessary in order to reach the project goals. Back on Track In Spring of 2024, our team prepared the gardens by controlling the weeds and fine grading the soils for planting. We then applied a 2-3” layer of twice shredded hardwood mulch in all of the gardens. In May and June, we installed nearly 15,000 3-4” container plants, composed of a mix of 15 Minnesota native plant species. We selected very tolerant native species that can withstand the rigors of life along a bustling roadway. Plant height was also a consideration. We introduced short grass prairie species along the side slopes of the gardens, and in the bottoms, we planted a mix of wetter prairie and a few wetland species that don’t mind saturated soils for extended periods. We used a mix of grasses and sedges for structure, along with wildflowers that bloom throughout the growing season. One of the highlights from last summer was a community planting event, led by Paul Chellsen and other City staff. An amazing turnout of truly passionate individuals learned about the project and helped address 10 rain gardens, installing over 1,500 plants. We had an impressive mix of volunteers, ranging in age from 6 years old to quite impressive super seniors. Maintenance Matters After installation, our team took charge of monitoring and maintaining the gardens on a weekly basis. This involved intensive weeding, watering (averaging 1” per week), and adding supplemental plants where necessary. This consistent care, combined with well-timed early summer rains, led to incredibly strong plant establishment with minimal weed cover. Although perennial plants put a lot of energy into root development the first year, the native plants on Grand Avenue really showed an impressive rate of growth. A majority of the forb species actually flowered last summer and the grasses and sedges expanded and grew to a height of 2-3’. The plants were very well rooted going into winter, which means that we should see even more rigorous native plant expansion and flowering this season. Challenges Along the Way Being in a very populated urban setting, we did have our share of trampled and uprooted plants from a wide variety of human activities. One unexpected issue had to do with an extremely ravenous rabbit population. The new garden plantings attracted bunnies of all ages. They keyed in on and chewed young shoots, leaves, and stems, which stunted and even killed hundreds of prairie plants. Our team had some luck with natural repellents, but diligent replanting ultimately helped mitigate damage over the summer. We fielded a lot of questions regarding why sand bags were blocking water from entering the rain gardens. Our message explained how the bags reduce runoff and give plants time to establish before large storm events. Over the summer, it was a constant challenge to replace damaged bags. Even with the bags properly in place, we had a few big storms that uprooted plants and pushed a great deal of mulch out of several gardens. This year, the gardens are on their own. The bags have been removed and the well-rooted native plants are ready for larger amounts of stormwater entering these systems. City and Natural Shore teams will be closely monitoring the effects of the now “normal” stormwater flows. Key Community Involvement The support and dedication of the Grand Avenue community highlighted this project. Whether volunteering at the planting event, advocating through word of mouth, or taking on garden projects, the involvement is invaluable. Our team repeatedly heard residents express gratitude for the dramatic improvements made and the ecological and aesthetic benefits the rain gardens bring. Our field staff greatly appreciated this feedback, which fueled their passion to work on this special project. Moving on to Bryant Avenue Rain Gardens We are excited to announce that we will be teaming up again with the City to establish native plant communities in a series of rain gardens along Bryant Avenue. We plan on using a similar approach and expect the same outstanding results. In addition, we will continue to manage the Grand Avenue rain gardens for another year. This will ensure that the plant communities continue to thrive. With the ongoing support of our partners and the community, we look forward to making these stormwater management tools truly exceptional – by being ecologically diverse, sustainable, beautiful, and incredibly valuable neighborhood amenities.
