By Tina Seaman
Due to this summer’s record heat, the native plants in the Lurie Garden, a perennial garden in Chicago’s Millennium Park, bloomed up to five weeks early. When WOWW spoke in early June to Jennifer Davit, the director of the Lurie Garden, she pointed out highly unusual combinations of plants in bloom at that time, such as spring bulbs, like tulips, flowering alongside salvia, which typically doesn’t blossom until several weeks later. Yet in spite of the heat and drought, the native plants at the Lurie Garden have not gone thirsty. This is thanks to their drought-tolerant qualities, such as deep roots that allow them to reach and store rainwater for long periods of time.
But, unlike the rich, deep soil of the remnant Illinois prairies, which is the model for the garden design, Lurie’s soil depth is only two to four feet. This is because the garden and all of Millennium Park (a total of 24.5 acres) was actually built in 2004 on top of one of the world’s largest green roofs, constructed above a parking garage, railroad tracks and former railroad station. The park is one of the largest areas of public green infrastructure in downtown Chicago and helped boost the city’s international image as a leading “green city.” This remarkable feat of urban landscape architecture is in part credited to Gustafson Guthrie Nichol Ltd., the landscape architecture firm that designed the Lurie Garden, along with Dutch planting designer, Piet Oudolf, who created the planting design.
Providing a model for gardeners at home
Millennium Park has become a Chicago icon and the Lurie Garden is one of its main attractions, but the garden also has become a model of sustainable urban horticulture for home gardeners and community planners. The garden plays an important role in demonstrating how gardeners can sustainably, naturally and cost-effectively maintain a beautiful native garden in the region’s climate by conserving water and not applying chemicals like fertilizers, insecticides or fungicides.
Native gardens conserve rainwater and provide stormwater management benefits, making them desirable for residents and communities. By not adding chemicals, the plants at the Lurie Garden attract and provide a safe shelter for migratory birds and a food source for beneficial insects, including honeybees that provide benefits like pollination. Overall, the long life and durability of the plants make them less costly to maintain. “The initial cost [of planting a native garden] may be more, but over time it is less expensive because you do not have to replant every year, and you save money by conserving water and not applying chemical products,” said Davit.
Piet Oudolf, Lurie Garden’s planting designer, selected native plants for nearly 60 percent of the garden, along with suitable non-native plants. According to Davit, the native plants were chosen for their water conservation benefits, ecological qualities, suitability to the region’s climate, and because they look attractive all year-round. Each of the plant’s qualities contributes to a balanced natural ecosystem. For instance, Monarda bradburiana (Eastern Bee Balm) and the Sporobolus heterolepis (Prairie Dropseed) together create a winning combination of drought tolerant native plants that also provide four season interest and habitat.
Thoughtful selection of perennial and native plant combinations is an important part of the garden’s horticulture model. At home, gardeners will soon be able to grow their own smaller version of Lurie Garden in their backyards by purchasing branded perennial plant combinations from Garden Artistry, modeled after the Lurie Garden. Do-it-yourselfers also can design their own native beds by consulting online resources, such as native plant inventories.
Water conservation benefits
Due to the extreme heat this summer, Lurie’s gardeners needed to water more than normal, according to Davit. “In a regular season, about half the garden doesn’t get supplemental irrigation,” explained Davit. Gardeners manually operate the irrigation sprinkler system to apply the necessary amount of water, not more or less. This entire system then runs on a timer that is consistently monitored and only triggers watering at midnight to avoid evaporation. Even with the increased watering this summer, the native rain garden still requires less water than a lawn of the same size (2.5 acres) because of the plants’ deep roots that can retain approximately 30 percent more water than a conventional lawn. This leads to both water and cost savings for the Lurie Garden, which was funded and constructed by the Founders of Millennium Park. The maintenance is funded by a stewardship endowment given by philanthropist Ann Lurie and all aspects of the garden are managed by the nonprofit Millennium Park, Inc.
Stormwater management benefits
The garden’s benefits are not only an asset in drought, but also in times of high-intensity rain storms. By converting the former concrete surface into natural green space, the garden captures rainwater on site and has dramatically reduced stormwater runoff. The garden is constructed in stratified soil, gravel, and geofoam layers on top of the concrete parking structure. Given that 85 percent of the garden’s five acres of surface area is permeable, it is able to infiltrate the majority of the water that falls onto it; the only water flowing off site is from the 15 percent of non‐permeable paved areas in the garden. This small percentage runs off into the drainage system beneath the garden, which takes residual stormwater to the city’s combined sewer system. Overall, the Lurie Garden reduces the load on Chicago sewers by nearly 2 million gallons per year – 28 percent more relief than would be gained from a conventional park site with lawns.
Sustainable garden maintenance
It is Davit’s responsibility to oversee the horticulture maintenance to make sure the Lurie Garden’s 35,000 perennials, 5,200 woody plants, and 120,000 spring flowering bulbs continue to thrive in this year’s uniquely hot conditions. Given that the garden encompasses more than two-and-a-half planted acres, Davit says horticulture maintenance in the summer months takes about 100 hours a week. But, she adds, thanks to the durable design, the plants require less maintenance than non-natives.
Another part of Davit’s role is to lead the educational programming for the garden, including a membership program to engage the community about the benefits of native gardens and how to replicate them at home. Regular weekly tours take place from mid-May through mid-September and attract up to 2,000 people annually. Davit also oversees workshops for home gardeners and horticulturists, as well as youth education programs, which reach more than 2,000 school-aged children during the summer.
The Lurie Garden has proven to be a vital asset not only to Chicago’s environment and wildlife, but also to the community – and Davit’s stewardship has played a key part in cultivating this important connection between nature and people.
The amount of rainwater the Lurie Garden retains on-site and out of Chicago’s combined sewer system every year.
By not applying chemicals, such as pesticides and insecticides, the Lurie Garden requires no expenditures on these types of products that are harmful to the environment. By choosing native plants for your home garden that are suitable to the climate and have disease tolerant qualities, you can save money by not purchasing chemicals.
The typical increased volume of rainwater that rain gardens infiltrate on-site, as compared with a conventional patch of lawn. By planting a native garden, the plant’s deep roots can naturally store water for longer periods of time until it is used.
Choose perennial and native plants, such as those planted at the Lurie Garden, to promote water conservation and plant and animal biodiversity. Forgo chemical application of fertilizers or pesticides by planting native plants, which will save you time and money while helping protect the environment. Learn more about creating and maintaining healthy soil. The native plants’ deep roots also absorb rainwater and help prevent against soil erosion.
Based on the models that emerged from the Field Museum’s Community Climate Action Toolkit, community gardens that help conserve water and manage stormwater runoff can also help link climate action to local strengths and priorities. This linkage is vital by empowering community members to steward their gardens and water resources and work together to have an impact on climate action.