The Polly Hill Arboretum on Martha's Vineyard

If you visited the PHA this spring, you probably noticed the new mixed border planting located in front of the Homestead along the wooden fence bordering State Road. Why would an arboretum, traditionally devoted to growing trees and shrubs, install a border featuring herbaceous perennial plants?

The Homestead Border was in need of attention. This area has a long history, from the time when colonial travelers stopped at Barnard’s Inn Farm for a pint, to Polly’s parent’s time when trees were planted to buffer noise from the road. The hurricane in 1991 brought down some of the shade trees along the road, and in 1998 the previously planted “buffer” trees and other old and diseased plants were removed to allow for an unobstructed view of the newly renovated Homestead. Ever since, this high profile area has contained a mixed lot of woody plants and persistent perennials and has been in need of more intentional plantings.

Tim Boland, then PHA Curator (and my husband), asked me to design a border planting that would set off the Homestead and announce the Arboretum’s presence on State Road. We hoped that the new planting might even entice passersby to stop in and see what the PHA is all about. To address the question asked above, the new border is not a traditional perennial border, but a mixed border. A mixed border employs a layered planting plan that combines trees, shrubs, perennials, and grasses to mimic the way plants grow in natural settings. My intent was to preserve existing woody plants, add more, and then combine them with herbaceous perennials to create a harmonious whole. The perennials would add color and lengthen the season of interest while the woody plants would provide height, structure, and a winter presence.

Tim and I worked together to select plants for the border. Sustainability was paramount. That is, we selected plants to match the conditions of the site—well-drained, acidic soil, high salinity from the road, sun or partial shade depending on the specific location, and other Vineyard climatic challenges like droughty summers and wind. Like Polly, we included some plants in the spirit of experimentation, ones we aren’t sure will thrive or survive the winter. If these plants prove hardy and prosper, we will have learned something, and if they don’t, we will have learned something too.

When designing a garden, I believe it is important to develop a concept that will guide you (along with site analysis) in choosing and placing the plants. Some of the guidelines we drafted included gardening in layers, the retention of existing plants when possible, planning for seasonal color to coincide with peak visitation, and an emphasis on long-lasting foliage texture and color. Finally, I devised a color scheme, an intense combination of hues based around a sunset theme. The type of sunset I had in mind would garner a round of applause in Menemsha – rich oranges, deep scarlet reds, intense magentas, bright pinks, and dusky shades of purple.

The existing plants in the border included both woody and herbaceous plants. A large sweet gum tree (Liquidambar styraciflua) provides shade on the south end of the border and evergreen hollies flank both ends. The ‘Beanpole’ yews, still quite small, will provide an interesting vertical accent when larger. Nodding lilac (Syringa reflexa), ‘ Mount Airy’ fothergilla, and leatherwood (Dirca palustris) were among the woody plants left in place. The familiar and showy tiger lilies and hollyhocks already growing along the fence are an asset and conveniently work perfectly with the new color scheme. We retained several peonies, ‘Purple Smoke’ baptisia, and the impressive giant fleeceflower (Persicaria polymorpha). We also left in place butterfly weed (Asclepias tuberosa), a plant that I have never fully appreciated until seeing it here on the Vineyard. Butterfly weed serves as a connection to the native landscape as well as a beautiful source of sunset orange flowers.

Baptisia 'Purple Smoke'

New woody plants include the classic crabapple ‘Louisa’, named by Polly after her daughter, which we added to frame the north end of the border. We chose Itea virginica ‘Henry’s Garnet’, the Virginia sweetspire, for its summer flowers, drought tolerance, and red fall color, and Caryopteris ‘Longwood Blue’ for its late-summer flowers and handsome gray-green foliage. We added Physocarpus opulifolius ‘Monlo’ Diabolo®, a selection of the common ninebark, for its spring flowers, vertical form, and attractive reddish purple foliage. The number of large woody plants was intentionally limited; our intent was not to screen the Homestead from the road.

We chose dozens of different herbaceous perennials to add to the border. Our criteria were drought tolerance, ease of culture, and beautiful foliage. A new perennial that meets these criteria is Panicum amarum ‘Dewey Blue’ a selection of the native switch grass often found growing on dunes in dry sand. This ornamental grass offers drought tolerance and striking steely blue foliage. Its form adds structure, but its cloud of flowers and natural beauty soften the design. Salvia daghestanica, the dwarf silver-leaf sage, is an experimental choice; I have never grown it. This little salvia forms rosettes of silvery foliage, later topped with blue flowers. My catalog claimed that the plant is resistant to browsing by deer and rabbits. We shall see! Of course, the border contains plenty of the more usual suspects that tolerate drought and look good, like creeping thyme, Russian sage, sedums like the plumy foliaged ‘Vera Jameson’, catmint, lavender, red valerian, and perennial sage.

I chose some perennials primarily to augment the color scheme, although they had to meet the other criteria as well. We planted several groups of Echinacea purpurea ‘Rubinstern’, a form of purple coneflower with large pink flowers; the prominent coppery central disk is an extra bonus. Echoing the flower shape but differing in color is Echinacea ‘Art’s Pride’, one of the new orange selections of purple coneflower. The tubular flowers of Crocosmia ‘Lucifer’ add a shock of scarlet red above pleated vertical foliage. Hummingbird mint, Agastache ‘Desert Sunrise’, contains flowers in shades of orange, pink, and lavender. (All these tubular red and orange flowers make the border a great place to find hummingbirds.) I also choose perennials whose fall foliage would continue the sunset theme. The cute little ornamental onion, Allium thunbergii ‘Ozawa’, has copper orange hues in the autumn along with the Arkansas blue star (Amsonia hubrichti ) and prairie dropseed (Sporobolus heterolepis ).

Arts Pride Coneflower

Suzy Zell, Tim Boland, Paul Cady, and volunteer Frank Smith, planted the border this May. Although plants were chosen for drought tolerance, we have been watering during dry spells to help the new plants become established. Most of the plants have settled in nicely and look healthy. We also added a layer of mulch to help conserve moisture and suppress weeds. Deer, skunks, turkeys, and rabbits have created some challenges, and consequently some of the more “delicious” plants have been caged. We also plan to plant bulbs this fall to add another layer of interest next year. Based on the response from docent tours and visitors alike, the border has attracted great interest. Combining the creativity of design with real-life gardening is always a learning experience. I know I will learn even more next year! – Laura Coit

Laura Coit, in addition to being Tim Boland’s wife, is a garden designer, garden writer, and horticultural artist.