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Gardens of the High Line: Chelsea Grasslands

by Timber Press on August 22, 2017

in Design

Big bluestem (foreground) stands over six feet tall in late October. Along with tall-growing companions switchgrass and Indian grass, its presence is as dramatic as any shrub.

Piet Oudolf and Rick Darke walk us through the Chelsea Grasslands, West 18th Street to West 20th Street

Grasses have always been essential to the High Line and always will be. Pioneers in the ecological sense, they were among the first living things to find opportunity in the derelict West Side Line’s emerging habitat. Aesthetically, they’re key to the pioneering urban naturalism that distinguishes the re-imagined landscape. Unlike their close relatives the sedges, most true grasses are sun plants, so it is fitting that Chelsea Grasslands, one of the sunniest spaces on the ’Line, is where they reach the zenith of their drama and diversity.

Changelings by nature, grasses contribute more to the gardens’ dynamic character than any other plant group. Their colors, though less saturated than typical flowering plants, are softly sophisticated and remarkably varied. Color diversity in grasses begins with greens, expressed in every imaginable hue, tint and shade. In autumn, green grasses turn gold, apricot, red and russet in a slow fade to fawn, while blue-green grasses become suffused with silver and purple. Grasses’ capacity for self-seeding ensures their patterns are ever in flux and inclines them to grow in large masses. Beyond color, grasses contribute a wealth of beauty and intrigue derived from unique qualities of line, form, texture and translucency. Their lissome stalks and flowers flutter and dance to every summer breeze, autumn storm and winter wind. As they move they sing in low tones ranging from a whisper to a staccato rattle. Grasses’ fineness provides beautiful contrast to the bold texture of broad-leaved plants, and their lightness makes them ideal companions to the opacity and fixed forms of art and architecture.

This simple but brilliantly balanced combination of Mount Everest Persian onion (Allium stipitatum ‘Mount Everest’) and Visions in Pink Chinese astilbe (Astilbe chinensis ‘Visions in Pink’) demonstrates that qualities of texture and form can be more visually powerful than flowers or color alone. In this mid-June scene the onion’s white flowers have become green globes as seeds begin to mature.

Big bluestem (Andropogon gerardii), Indian grass (Sorghastrum nutans) and switchgrass (Panicum virgatum) are primarily responsible for the grassy splendor of Chelsea Grasslands. Along with little bluestem (Schizachyrium scoparium) they are the dominant species of the North American tallgrass prairie, however all are also native to the east, including the New York region. Physiologically, they are warm-season types, and warm-season grasses like it hot, growing best when air temperatures exceed eighty degrees Fahrenheit. They’re slow to start in spring and have little height or presence until late May or June. By late summer they’ve achieved their full stature and mass, radically transforming the entire scale of the landscape.

This house sparrow is one of many birds, both introduced and native, that find sustenance in the maturing seeds of grasses such as prairie dropseed. Unusual among grasses, prairie dropseed flowers are powerfully fragrant. The scent has been likened to crushed cilantro or burnt buttered popcorn.

Lower-growing than its tallgrass prairie companions, little bluestem is least adapted to growing in close proximity to broad-leaved species, especially in densely planted combinations. Though little bluestem is represented in Chelsea Grasslands, the lower tier of grasses is mostly comprised of North American native prairie dropseed (Sporobolus heterolepis) and southern European native autumn moor grass (Sesleria autumnalis), both of which have proved capable of thriving in the intricate mix.

In October and early November the brilliant gold color of threadleaf bluestar sets off aromatic aster and Shenandoah switchgrass.

Choosing colorful flowering companions to grasses is an art in itself. Though grassy growth is relatively low in spring, it is a potentially overwhelming force in summer and autumn. To survive, plants must take advantage of available light at ground level early in the year, then have strategies for tolerating the shade and competition of grasses in later seasons. Some, such as irises and prairie dock (Silphium terebinthinaceum), persist by means of strong, often deep root systems. Others, such as asters, grow tall along with the grasses, flowering in late summer and fall. Many bulbs, including daffodils, species tulips, crocuses, grape hyacinths (Muscari), squill (Scilla), onions (Allium) and snowdrops (Galanthus), go dormant after they flower and set seed and are unaffected by the lack of summer sunlight. Chelsea Grasslands’ design carefully matches grasses and companions to create a sustainable all-seasons landscape.

Woody plants—trees and shrubs—play minor roles in Chelsea Grasslands with the notable exception of a few burr oaks (Quercus macrocarpa). This North American native tree frequently occurs with grasses from the Atlantic to the Great Plains. The oaks’ inclusion is one of the High Line’s many experiments, and to date they are thriving despite limited rooting space. The ground below them is covered by a dense, weed-suppressing mix of grasses and colorful flowering plants including meadow sages (Salvia pratensis cultivars ‘Rhapsody in Blue’ and ‘Pink Delight’), which sustain themselves in part by self-sowing. Light yellow twisted-leaf onion (Allium obliquum) blooms with them in May.

The High Line’s seasoned staff is trained to recognize many indicators of plant health that are revealed by the newly trimmed landscape. Some plants may need renewal by division. Self-seeding tendencies of others may require encouragement or control. The cutback is an essential tool for preserving the vigor of the High Line ecosystem and the integrity of its design. Photo by Annik La Farge.

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Piet Oudolf is among the world’s most innovative garden designers and a leading exponent of naturalistic planting, a style that takes inspiration from nature but employs artistic skill in creating planting schemes. Oudolf’s extensive work over 30 years of practice includes public and private gardens all over the world. He is best known for his work on the High Line and Battery Park in New York, the Lurie Garden in Chicago’s Millennium Park, Potters Field in London, and his own private garden at Hummelo in the Netherlands.

Rick Darke is a landscape design consultant, author, lecturer, and photographer based in Pennsylvania who blends art, ecology, and cultural geography in the creation and conservation of livable landscapes. Darke served on the staff of Longwood Gardens for twenty years, and in 1998 he received the Scientific Award of the American Horticultural Society. His work has been featured in the New York Times and on National Public Radio. His books include The Encyclopedia of Grasses for Livable Landscapes, The American Woodland Garden, and In Harmony with Nature.

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Click image to look inside this book.

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“If you can’t get to the High Line, the image-rich publication is the next best thing. In some ways, it’s better, because its pictures bring home the seasonality of the plants.”—Washington Post

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