When Plantsmen Plot

Genus by genus, two Pennsylvania gardeners have blended their collections into a dazzling display

AS DAVID CULP AND MICHAEL ALDERFER showed me around their garden last November, what I saw was, in many ways, typical of the season in southeastern Pennsylvania. Several hard frosts had blackened most of the perennials and annuals, and all but a few had been cut down and added to the compost pile. The deciduous trees were mostly bare, the sad odor of fallen leaves a signal to most gardeners in these parts that the end of the gardening season is near.

But suddenly Culp dropped to his knees on the gravel path. Looking down, I saw the diminutive object of his adoration: a clump of snowdrops, one of 42 different species and forms to be found in this two-acre garden. I have never been a great fan of snowdrops, but Culp’s enthusiasms are infectious, and I soon found myself kneeling beside him, peering into one of the flowers, trying to discern what made this specimen of the genus unique, other than its name: Galanthus nivalis reginae-olgae subsp. reginae-olgae corcyrensis—a cumbersome appellation that seems longer than the plant is tall.

This is Culp’s favorite way to share the garden with visitors: on the ground, face pressed close to the plants as he tries to explain their subtle botanical differences. In others this would be mere pedantry, but Culp approaches his garden with such an air of childlike wonder that visitors can only smile and try their best to love what he loves. “I want people who come here to react to the garden emotionally,” he says. “It’s not just a cerebral game. I want them to feel it, touch it, smell it—like I do.”



1. Hillside garden

2. Ruin garden

3. “Jewel Box”

4. House

5. Mixed borders

6. Vegetable garden


An incorrigible optimist, Culp saw only potential when he bought the slightly rundown 1790 farmhouse and adjoining two acres in 1990. (Alderfer joined him there in 1993.) The house sits on a relatively flat, rectangular acre below a steep hillside of roughly equal size. The gardens closest to the house were developed first. These include the “Jewel Box,” a raised bed that became home to a number of small rarities that might have been lost in a larger setting, and the walled ruin, or rock garden, which first had to be cleared of tires, automobile fenders, and other accumulated junk left behind by the previous owner. The transformation of the overgrown hillside, begun about five years ago, is still underway. The understory on the hill was a six-foot-high tangle of invasive vines and shrubs, and Alderfer had to cut it down twice by hand before any planting could begin. He and Culp also limbed up the trees, to give a clear view to the hilltop from the flat area below.

A few of the dead trees on the hillside were left standing to provide a habitat for wildlife. Alderfer cut out most of the poison ivy, but left a few of the oldest vines alone, as their berries are a rich source of food for birds, which both he and Culp love. Inside the house, Christopher the canary sings and whistles incessantly, while outside, the garden is home to a dozen Old English Bantam chickens. Small enough not to trample the plants as they scratch for insects and grubs, Culp sees them as living garden ornaments, adding a moving, feathery, gently clucking presence to the beds.

An irrepressible collector, David Culp has managed to channel his passion for plants to create a coherent, yet richly varied, whole.

Surrounded by mixed borders on all four sides, the fenced vegetable garden also faces four additional discrete mixed borders, separated by lawn.


Culp works for Sunny Border Nurseries, a Connecticut wholesale grower, in both sales and research and development. In the latter position, he spends from four to six weeks a year traveling around the world looking for new plants that the nursery might acquire and bring to market. These trips also afford him a perfect opportunity to feed his personal passions. In Italy a number of years ago, he saw how Arum italicum grew wild in the dry hillsides around Rome, and has since been buying unusual specimens for his own dry hillside. In England, he fell in love with the multitude of hepatica hybrids at one nursery, recalling, “I had my camera around my neck, but I was so stunned by the plants that I forgot to take any pictures.” Last year he spent two weeks in Japan at the peak of iris season. “I went to a Buddhist temple where the monks had been cultivating Iris ensata [Japanese iris] for 500 years,” he says. “Talk about a religious experience! The forms, the colors! I’ve got to find a way to get them to the U.S.”

“If I like a genus, I indulge myself in it completely,” Culp says. “When it comes to gardening and plants, I’ve always been irrepressible. I lived in apartments where all the windowsills were full and you couldn’t walk out on the balconies because of all the plants.” Besides the snowdrops (the earliest of which bloom in September and the latest in March), the garden includes collections of roses, hepaticas, hardy geraniums, kniphofias, cyclamen, euphorbias, arums, and peonies. In each of these groups, many of the species and forms are rare or unusual, with interesting leaf shapes or variations and stunning flower colors and forms.


The garden’s “signature genus,” however, is Helleborus—the hellebores—which Culp has been collecting for 20 years and breeding for more than a dozen (see box below). Culp’s collection numbers in the hundreds, with 50 double-flowered forms alone, and he is constantly adding to it with his own new hybrids and those of other breeders. Besides their wide range of flower colors—from near black to white and with many shades between—Culp admires hellebores for their evergreen foliage and for their ability to grow almost anywhere except in standing water and full, baking sun.

“But what first captured me was their spirit, their gumption for blooming in February, or even January some years,” he says. Large sweeps of hellebores—in the beds around the house, on the hillside, and elsewhere in the garden—now form the core of the garden’s winter show. Strong supporting roles are played by galanthus, adonis, winter jasmine (Jasminum nudiflorum), and the tiny but graceful Narcissus ‘Cedric Morris’, which blooms on and off from September to March. Providing the backdrop for these flowers are the golden russet foliage of several forms of carex, the black strappy leaves of black mondo grass (Ophiopogon planiscapus ‘Nigrescens’), the shiny dark green arum foliage, and various evergreen ferns such as Dixie wood fern (Dryopteris xaustralis), one of Culp’s favorites. These flowers and greenery work to shift the sense of the seasons, easing the catalog-flipping tedium of the usual gardener’s winter. “It took time, it was a challenge,” Culp says, “but we’ve managed to do away with the dormant season here.”

Talking about Design

THE FOCUS of my breeding work with hellebores is the color and shape of the flower. Clarity of color is primary—colors should be unmuddied by green. Markings should be uniform. New colors such as peach and gray have been added in recent years to the classic array. The shape of the flower is equally important. The goal is flowers that are uniform and rounded or star-shaped with overlapping sepals. Double and anemone-centered flowers are exciting new trends.—David Culp

Left: A partly shaded graveled area near the house plays host to an array of self-seeders and potted specimens. Right: Hellebores occur throughout the garden. Helleborus foetidus lines this staircase up the hillside, along with ferns, hostas, and heucheras.


Part of the genius of the garden is that Culp and Alderfer have managed to blend their many plant collections into a seamless whole. It helps that, instead of single specimens, the collections contain dozens, even hundreds of forms of various genera, and that the plants have been intermingled in various beds (rather than grouped together by genus as in a botanical garden), which provides a continuity of form throughout the garden.

The addition of more common plants with upright forms is another unifying theme. Some of Culp’s favorite combinations—those that he says “get me drunk in the garden without drinking”—include the foxgloves, pillar roses, and Siberian irises of late May; and around Fourth of July, Acanthus mollis, Lilium regale, and Thalictrum rochebruneanum ‘Lavender Mist’. Another similar moment happens in early May, in the rock garden. With the foliage of the evergreens fresh and new, the wall awash in the pink cascades of Saponaria ocimoides, and the nepeta in full bloom on the ground, the black locust tree above drops its flowers over everything, like fragrant white snow.


It certainly doesn’t hurt that the garden has a great layout and hardscape—what designers refer to as “good bones”: the old house and trees, solid hedges and stone walls, the setting of the ruin for the rock garden, the hillside’s dramatic changes in elevation. “Bones are important,” Culp says. “But what we’re trying to do is breathe life into those bones.” One way they do this is by allowing plants, such as hawkweed (Hieracium spp.) and several Corydalis species, to naturalize in the garden, leaving the plants they want and editing out the rest. These self-sowers, along with plants such as Geranium ‘Ann Folkard’ and Campanula poscharskyana that weave and wind among their neighbors, help loosen up the design, filling in gaps and making the garden look older and more established than it is.

“I love gardens that have a mind of their own,” Culp says. “The idea isn’t to duplicate Mother Nature, because that’s impossible, but we want to try to catch her spirit. People sometimes forget this spirit. They get hung up on rules. They think that this color can’t go with that one; they’re always thinking, ‘What am I doing wrong?’ When you start out you need rules, but after a while you can put them away in a drawer. And if you dare to break some of those rules, you begin to realize that this isn’t deadly serious. It’s a garden, it’s fun.”

Although the normal habit for a shrub rose is a free-standing bush, many, such as ‘John Cabot’ (this page; in the Explorer series) and ‘Carefree Beauty’ (opposite; a Griffith Buck rose) can also be trained against a wall or treffis.

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