Lurie Garden: an urban oasis
Among the world’s largest green roofs, it offers safe haven for birds, butterflies, bees
a sombre orange sun slowly rises over Lake Michigan — it seems to be in no particular hurry this morning — and that’s a good thing.
It’s just after 7 a.m. and I’m exploring a prairie meadow filled with gentle grasses and wildflowers; generous footpaths, an arrow-straight watercourse and skyscrapers in the distance are a nod to the city, but for now, it’s easy to lose myself in the meadow. I take a deep breath: The warm air smells of sweet summer meadows, I can hear the sound of birdsong and buzzing insects. Across the meadow, a troupe of monarch butterflies flutter among the spires of violet-blue of hyssop.
It’s easy to imagine that I’m in a prairie meadow, far from the city limits, but in fact I’m in Chicago’s Lurie Garden (www.luriegarden.org ), built over parking garages and an active commuter railroad, and when combined with other areas of Millennium Park it becomes one of the world’s largest green roofs.
Designed by Gustafson Guthrie Nichol Ltd. and the venerable Dutch plantsman Piet Oudolf, the garden celebrates Chicago’s transformation from flat marshland to innovative green city with a four-season palette of interest.
The plants were carefully chosen based on growth habit, leaf and flower shapes, seed heads and winter forms. Many of the plants are native to North America and were selected for their longevity and self-sufficiency. The meadow offers a safe haven for birds, butterflies, bees and beneficial insects in the middle of a busy city.
Besides creating a habitat for wildlife and a natural oasis for city dwellers, the green roof helps to reduce storm water runoff by retaining 1.85 million gallons of water a year. The garden is free draining. Water not absorbed by the garden moves to a waterproof membrane and drainage system below. No synthetic pesticides or fertilizers are used on the perennials. More than 80 species of birds and 10 species of butterflies have been documented in the Lurie Garden.
Late August can be a challenging time in the garden, many summer flowering plants are winding down.
Let’s take a closer look at four perennials at Lurie Garden that can help you stretch the flowering season well into autumn. They all are attractive to butterflies and pollinators.
Giant hyssop (Agastache ‘Blue Fortune’)
was a butterfly magnet at Lurie Garden. This herbaceous perennial reaches heights of 60 to 90 centimetres and prefers a welldrained soil in full sun. It dislikes wet, poorly drained soil and may not survive the winter in wet clay soils. With showy spikes of lavender blue flowers from July to September, the dried spires look attractive in naturalized gardens over the winter. Agastache ‘Blue Fortune’ blooms freely over the summer, the leaves have pleasant minty-anise fragrance and can be added to potpourris or used to flavour beverages. Good cut flower and very attractive to butterflies.
Sea lavender (Limonium latifolium)
offers dense clouds of minute lavender coloured flowers that peak in August and September. This hardy perennials earns its keep early in the year with a shiny green rosette of paddle-shaped leaves that act as an attractive ground cover below early flowering perennials. At the Lurie, sea lavender is used as a finely-textured backdrop for tall, rougher plants such as coneflowers, Russian sage and switchgrass. Sea lavender reaches heights of 45 to 75 cm and features tiny lavender-blue flowers that appear on virtually leafless stems; it prefers full sun and blooms in the summer, but peaks in August and September. Leave it standing for winter interest. Excellent as a cut flower or dried for winter arrangements.
Prairie petunia (Ruellia humilis)
is a North American native that accepts full sun to part shade and the dryish soils of open woods, glades, prairies and meadows. Lavenderblue, petunia-like flowers bloom from May to October on plants that reach heights of 45 to 60 cm. It is attractive to butterflies. At the Lurie, the prairie petunia was paired with several different companions: it poked its head through a patch of sea lavender, a perfect colour echo; it dotted meadows of prairie dropseed grass, and drifts of prairie petunia painted the edges of the meadow.
Compass plant (Silphium laciniatum)
has clusters of cheerful yellow flowers and a towering habit, it can stretch 1.5 to three metres tall. The flowers are held high above the tall prairie grasses so pollinators can access them. They prefer full sun and medium, well-drained soil, but they also tolerate poor soils. Excellent as a strong vertical element in naturalized gardens and prairie meadows. The common name of compass plant comes from the plants habit of orienting its large, deeply cut, coarsely textured leaves to a North-South axis along the ground to minimize intense overhead sun exposure. The upper leaves are smaller. The compass plant develops a very deep taproot with a thick stem. It can reach six metres below the ground. Not surprisingly, it may take a year or two to establish itself before it flowers. It is attractive to birds and pollinators, it is a source of winter food for birds.