Ferns tend to be thought of as background plants used to fill empty space—but they're so much more. A preserved New York garden shows that ferns can be much more than a feathery frill.

By Tovah Martin
October 03, 2018
Often overlooked as simple groundcovers and fillers, feathery ferns are the star of the show in this New York garden.

In spring, mature arboretum-quality trees rub shoulders beside massive rare azaleas and rhododendrons at Rocky Hills in Mt. Kisco, New York, one of more than 80 distinctive gardens across the United States that have been preserved by The Garden Conservancy. Brightly colored blossoms abound, but another marvel is happening simultaneously at ground level. Lapping at ankles and tickling shins are fronds of every description. Through the years, vast fern colonies have interwoven their lacy brocade in waves of subtle green shades. But these ferns are not default groundcovers. Instead, the intricate network is a carefully curated collection. And the 80 distinct varieties of Pteridophytes (ferns and similar plants) in residence provide the perfect complement to the colorful shrubs and flamboyant bulbs of spring.

At present, Rocky Hills is a showplace for fiddleheads underfoot. But before 1990, attention was focused overhead. The garden began in 1956, when Henriette Granville Suhr, the head of furniture and interior design showrooms for Bloomingdale’s, and her husband, William, purchased the 13-acre farm as a weekend retreat. They had no serious background in gardening, but they discovered a passion for it as they transformed the property from bramble-infested eyesore into a haven of outstanding shrubs and trees.

Related: Guide to Fern Care

Fern expert John T. Mickel stands among Henriette Suhr's vast fern garden, which he helped create with plants from his personal collection.

Planning a Shady Garden

By 1990, the garden had become a serene shady scene. Considering how to make use of the shade canopy, the then-widowed Henriette contacted fern expert John T. Mickel, Ph.D., senior curator emeritus at the New York Botanical Garden, and asked for advice on amassing a collection. A friendship was forged, and Mickel—who has 150 different ferns in his own yard and who authored Ferns for American Gardens (Timber Press; 2003)—ultimately shared 80 ferns from his personal garden collection. With his expertise as a scientist and Henriette’s talent as a designer (she spearheaded the concept of retail store showroom furniture displays), they pulled together a carefully documented carpet of ferns that creates the feeling of wading through the forest primeval.

It turned out the garden’s dappled shade was ideal for ferns. Henriette avoided planting beneath groves of conifers, which furnish too dense of a canopy. Trees with surface-root competition, such as Norway maples, can also jeopardize thirsty ferns. Despite the predominating rocks that gave Rocky Hills its name, Henriette found soil pockets between the stone formations to plant. She watered frequently, especially when the fernery was being established. Other than needing water and pine-bark mulch to prosper, the plantings quickly slipped into autopilot to form a luxuriant, magical Oz.

Painted ferns (Athyrium niponicum var. pictum) provide a backdrop for a vibrant mix of azaleas, rhododendrons, bluebells, primroses, forget-me-nots, and more.

Long-Lasting Foliage

The result is a harmony of crosiers in the full spectrum of green with touches of frosty silver and burnished bronze from relatively colorful painted ferns (Athyrium niponicum var. pictum). The frond carpet lets the azaleas and rhododendrons shine, while low-growing ferns form a flowing weave below spring flowers such as Spanish bluebells (Hyacinthoides hispanica), primroses, forget-me-nots, and spring bulbs. And spring is only the beginning, because most ferns persist in prime plumage through autumn, providing a soothing green seafoam interlaced among hostas, Jack-in-the-pulpits, Solomon’s seal, and hardy begonias. They might not be “look at me” plants, but ferns go the distance with subtle style.

Although Henriette passed away in 2015, Rocky Hills and its collection of ferns flourish under new stewardship. The current owners continue the Suhrs’ dedication and open the garden to the public through The Garden Conservancy Open Days Program. Visit gardenconservancy.org for more details about this year’s Rocky Hills Open Day on May 19, 2018, and become immersed in verdant paths with fiddleheads swishing at your feet.

Related: Silver-leaf Plants for Your Garden

A lush carpet of sensitive fern and ostrich fern scattered with forget-me-nots thrives under the shade of a hefty dawn redwood.

Fern Plant Combinations

Beneath the lacy shade of a dawn redwood (Metasequoia glyptostroboides), a tapestry of sensitive fern (Onoclea sensibilis) and ostrich fern (Matteuccia struthiopteris) weaves together with forget-me-nots (Myosotis scorpoiodes). With green as a base color, the purple and yellow flowers pop. A simple wood bench sits at the edge under the redwood, providing the perfect place to enjoy the natural beauty.

The uniquely shaped crested hart’s tongue fern (left) and yellow-green northern maidenhair (right) overlap zones and thus can coexist in this garden.
The uniquely shaped crested hart’s tongue fern (left) and yellow-green northern maidenhair (right) overlap zones and thus can coexist in this garden.

Planting for Your Zone

The fascinating fronds of the crested hart’s tongue fern (Phyllitis scolopendrium ‘Crispa’) look exotic, but actually are perfectly hardy from Zones 5–9. Unlike most of its fellow ferns, the hart’s tongue prefers some lime in the soil. Seemingly delicate but surprisingly stoic, the northern maidenhair (Adiantum pedatum) spreads to form a handsome colony of chartreuse fronds. It is hardy in USDA Zones 2–8.

Related: Understanding Your Hardiness Zone

Some species of fern, such as autumn fern, change colors during the growing season.
Some species of fern, such as autumn fern, change colors during the growing season.

Fern Colors

In May and June the Rocky Hills gardens are filled with spring-blooming bulbs, shrubs, perennials, and flowering trees, as well as banks of graceful ferns. While green is often associated with spring, not all ferns show green foliage early in the year. The young foliage of autumn fern unfurls striking orange and bronze fronds before turning green in summer.

Himalayan maidenhair (Adiantum venustum), painted fern (Athyrium niponicum var. pictum) and Christmas fern (Polystichum acrostichoides) form a tight groundcover that prevents weeds from taking root.

Groundcover Plants to Control Weeds

Forming a dense groundcover to muscle out weeds, a crazy quilt of Himalayan maidenhair (Adiantum venustum), painted fern (Athyrium niponicum var. pictum) and Christmas fern (Polystichum acrostichoides) hugs the ground between the eponymous boulders of Rocky Hills. The mix of lime, silver, and emerald foliage creates depth and emphasizes the unique texture of each fern variety.

Related: Easy Groundcover Plants

Ferns can thrive in a variety of environments, including squeezed between large boulders.
Ferns can thrive in a variety of environments, including squeezed between large boulders.

Gardening in Rocky Soil

Ferns find a way to tuck themselves into all kinds of nooks and crannies. Although the rocky base of this stone wall might not be optimal, ostrich fern (Matteuccia struthiopteris) and painted fern (Athyrium niponicum var. pictum) nevertheless find a way to thrive. These varieties cover the color bases: classic green and something with a little more pizzazz, like variegated cream, mint and plum.

Related: Rock Garden Design Ideas

Trees are a must for providing the cool, shady growing conditions that ferns need.

Shade Trees

Many mature trees at Rocky Hills—and there are dozens of species—create the dappled shade that ferns enjoy. The spotty shade keeps ferns (and other shady plants) cool and wet, and keeps the hot sun from singeing delicate foliage and flowers.

Source: Country Gardens Spring 2018
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