During September, Friends of the High Line is celebrating the Chelsea Grasslands – a special area of the park between West 18th and West 20th Streets that was inspired by the tallgrass prairie of the American Midwest. Through themed tours, family programming, social media, food, and a panel featuring High Line planting designer Piet Oudolf, we’ll highlight the heritage, design, plant ecology, and cultural history of the grasslands. Below, High Line Gardener Erin Eck delves into the challenges of designing and maintaining a grassland garden on the High Line.

Inspired by the tallgrass prairie of the Midwest, the Chelsea Grasslands evoke an American landscape that has largely vanished. While many people think of the prairie as a monotonous sea of grass, it was actually quite varied with ecological niches formed by changes in soil moisture, wind exposure, and topography. In The Elemental Prairie, John Madson writes:

The tallgrass prairie swarmed with wildlife. It wasn’t uniform, featureless range. There was a variety of habitats: ridgetops with short midgrasses, hillsides and flats with deep grasses, upland groves, heavily timbered floodplains, and the endless sumac and plum woods borders… The prairie then was strewn with small lakes, potholes, and marshes, and veined with tiny creeks.

Evoking this varied, open landscape is no small feat on a structure no more than 30 feet wide. How does one interpret the prairie on a small-scale? Piet Oudolf, who designed the High Line’s gardens, selected many plants native to the Midwest. Bur oaks (Quercus macrophylla), big bluestem grasses (Andropogon gerardii) and compass plants (Silphium laciniatum) rise above the burgundy switchgrass (Panicum virgatum ‘Shenandoah’). By mixing non-natives like meadow sage (Salvia pratensis ‘Pink Delight’), foxtail lily (Eremurus stenophyllus), and pincushion plant (Knautia macedonica) into the design, Oudolf created variation in color, form and height that reflect the diversity of the prairie.

Bur oaks (Quercus macrocarpa) add a new dimension to the garden without detracting from the feeling of openness.Photo by Ayinde Listhrop

Equally challenging to designing a grassland garden, is maintaining one. In his book, Planting: A New Perspective, Oudolf writes, “The skills required by gardeners are clearly different for this new vegetation-style planting… The trained gardener or landscape manager of the future will need a grounding in basic ecological science and an ability to use science to guide their intuition in managing complex planting.”

I spoke with gardener Rachel Hokanson, who manages the Chelsea Grasslands, about the unique challenges presented by a grassland garden and what we’ve learned over the years. The Chelsea Grasslands change so dramatically over the seasons that the fall garden is virtually unrecognizable from the spring. It’s hard to imagine that the sparse, low green spring garden will transform into the dense, tall, tawny garden of fall. The grasslands gardener must be able to envision this transformation and avoid planting too densely in the spring.

Gardener Rachel Hokanson cuts back last year’s growth. After cutback, the garden will look sparse for a few weeks.Photo by Ayinde Listhrop

As in any dense planting, competition is high in the Chelsea Grasslands. “A knowledge of how different plants reproduce, how fast they grow andif they will take over in the garden are all important ecological functions to recognize as a gardener,” Hokanson explained.

For example, a seedling of big bluestem can grow into a large clump over the course of the season, crowding out other perennials. Aggressive plants like big bluestem must constantly be kept in check. Other perennials, like sneezeweed (Helenium sp.), simply haven’t thrived in the site conditions leading Hokanson to seek replacements that work at both the ecological and design levels.

Designed to change over time, the Chelsea Grasslands are constantly in flux. Studying plant ecology and observing how species behave in cultivated conditions enables the gardener to guide changes while remaining true to the original vision. Far from a replication of the wild prairie, this garden connects visitors to that landscape by emphasizing elements of it. Through pattern, color, texture, sound, scent and motion, the Chelsea Grasslands offer visitors a glimpse of a largely lost American wilderness.

Celebrating the Chelsea Grasslands is made possible, in part, by TD Bank—the Presenting Green Sponsor of the High Line.