Renovating an Existing Border

Success requires both imagination and sensitivity to the site’s history

IN OUR PREVIOUS two articles, we described the challenges of creating borders on new sites—starting from scratch, so to speak. Implementing a new planting plan within a previously existing layout poses a different set of challenges, which we will discuss here.

THE SETTING AND DESIGN

Some years ago we were called in to work on a courtyard garden on an island near Seattle. The garden, which had been in existence for nearly 80 years, had originally been designed as a country retreat and was still used for that purpose by the current owner, who lived there primarily in the summer months. The garden’s basic outline hadn’t changed since its inception: enclosed on three sides by buildings, the garden opens out on the fourth side to a view across a small swale of a hillside pasture and towering conifers. Native sandstone pathways laid out in a cruciform pattern radiate from a Mogul-style fountain in a circular pool, creating four planting beds.

The mission our client gave us was to implement a blue, white, and yellow color scheme based on a watercolor that her father had painted almost 80 years before. Although this may sound straightforward, defining color can be a tricky business, since every primary and secondary hue has an infinite number of shades and tones, and perceptions vary from individual to individual. In this case, it was the blue flowers that were problematic. Because they were integral to the design, we introduced some “true” blues, being careful to keep them away from the mauvish blues. This led our client to conclude that too many of the established flowers were mauve or lavender (Scabiosa ‘Butterfly Blue’ was one example). We gradually removed these offenders, but the more our client tried to refine the color palette, the trickier the task became. Ultimately, we arrived at a compromise, which was simply to always try to find more and better blue flowers.

While the general layout of the garden was simple, elegant, and sophisticated, our client wanted the plantings to have the relaxed, natural feel of a summer bouquet from the garden and surrounding countryside. We therefore took a large part of our inspiration from the local fields and verges, with their seemingly random repetition of species.

A COLORFUL MISSION Implementing the client’s desired blue, white, and yellow color scheme involved retaining the best of the existing plants and supplementing them with new annuals, perennials, bulbs, and shrubs. Experimentation also played an important role.

In carrying out the new design, we had to take care not to erase the footprint of what had been laid out over the previous decades. Two red-leaved Japanese maples (unknown cultivars of Acer palmatum), for example, provided a richly colored canopy on the north and south sides of the courtyard. Boxwood balls announced where pathways ended or changed course, serving as invaluable anchors. We decided to add four more balls, but unfortunately, both the maples and boxwoods were suffering from phytophthera, a soilborne disease, so we opted for yew. We also avoided too much digging and gashing of the established plants’ root systems, which would have hastened their decline.

ROSES AND PERENNIALS

Since the garden was used mainly during the summer months, the earlier plantings had relied heavily on summer-blooming herbaceous perennials and roses. A previous designer had introduced numerous shrub and climbing roses, a number of which were pink. We removed the pink varieties, retaining those that were white or yellow flowering. The shrub rose ‘Golden Wings’ was the most satisfying of the lot, producing continuous flushes of bloom throughout the summer.

Among the existing perennials, we decided to retain large clumps of Phlox paniculata ‘Mt. Fuji’, Agapanthus Headbourne hybrids, and the imposing gray-leaved, white-flowered matilija poppy, Romneya coulteri. The romneya had been well placed, in two large masses, and so it stayed where it was. With the phlox and agapanthus, the question was one of balance and placement. Ultimately we decided to place both in all four beds, to provide continuity (although in an asymmetrical fashion). Since the agapanthus are shorter than the phlox, we placed them in irregular groups flanking the pathways, where one could admire the flowers and subsequent seed heads.

With the “continuity” plants thus established, we felt free to experiment without the constraint of making sure that there was some of every new plant in each bed. We did want to repeat certain shapes, however, and so we introduced Inula hookeri, with its narrow yellow ray flowers, in two beds closest to the house, and Aster xfrikartii ‘Monch’ in the two outlying beds. We also played a bit with the agapanthus, using more white-flowered plants closest to the house and blue ones in the outlying beds.

Another challenge, which affected primarily the choice of yellow-flowering plants, was our client’s aversion to including anything that resembled a sunflower (sunflowers were supposed to be grouped in another part of the garden). We had partial success in arguing that at least some members of the daisy family should be admitted, hence the presence of Aster xfrikartii ‘Monch’ and Inula hookeri, along with cutting-grown strawflowers (Helichrysum sp.) and assorted small-rayed critters that snuck in under the radar. In particular, xSolidaster ‘Lemore’, a bigeneric aster-goldenrod hybrid, performed beautifully and overlapped with the ‘Mt. Fuji’ phlox.

EARLY IN THE SEASON Although the border is intended primarily for summer display, Allium ‘Mount Everest’ provides interest before the other flowers hit their stride.

ANNUALS

Originally, our client had thought it would be possible to create a long summer bloom season using only perennials. Even with the addition of new, long-blooming varieties, however, there were still times when there was more foliar than flower coverage. We suggested the addition of annuals, since they can provide a longer season of bloom than many perennials. Accordingly, ‘Rocket Yellow’ and ‘Rocket White’ snapdragons were added for high-summer color, along with Lobelia richardii, Ageratum ‘Blue Danube’, A. ‘Blue Horizon’, and Lavatera ‘Mount Blanc’ for mid- to late summer. These plants were able to provide most of the color in each of the four beds, and so in subsequent years we made sure to allow plenty of room for an annual component. The exact selection of annuals changes yearly, since new varieties come onto the market that we want to try, and we need to take into account our client’s likes and dislikes. We have also incorporated certain plants, such as forms of Brugmansia arborea, that give the garden a slightly exotic feel and extend interest into autumn, while echoing the shape (and heady scent) of existing trumpet lilies.

NEW SHRUBS

Because space in the garden is limited and our client’s interest is primarily in flowers, the few shrubs and trees we have added are meant to punch up the color scheme. One of our first choices was Robinia pseudoacacia ‘Frisia’, whose bright yellow foliage, illumined by the afternoon sun, drew one’s eye upward to the distant dark forest. Alas, it failed before we had a chance to see how well it would have performed. In its stead, we planted a small Cornus kousa ‘Sunsplash’. Although this selection of the Chinese dogwood lacks the dazzling yellow foliage of ‘Frisia’, it can take full sun and will provide the upward movement we desired. When it gets a bit larger, it will make a good support for a well-behaved blue-flowered clematis.

A PLACE FOR CONTAINERS Large pots of Argyranthemum ‘Dana’ around the circular pool chime perfectly with the color scheme and also serve as a structural element.

For shrubs of middle height, we planted Cornus alba ‘Sunshine’ and Philadelphus coronarius ‘Aureus’. Both plants respond well to pruning—an important consideration in this garden, since they need to be kept in scale. Because the philadelphus can scorch even in our cool maritime climate, we sited it off to one side, where it’s partially shaded by a combination trellis/arbor. A nearby clump of Artemisia lactiflora Guizhou Group provides relief from the mid- to late-summer doldrums.

Clematis ‘Perle d’Azur’, a vigorous selection, sprawls through the arms of the cornus. We chose this cultivar because it can (and should) be cut back each winter, thus making it easier to prune the cornus. The contrast between the strong blue flower and yellow foliage provides several months of pleasure and requires little upkeep other than the occasional gentle nudge to direct the growth of the clematis.

Hydrangeas seemed like a natural choice for the garden, but the results have been mixed. The garden’s soil has a variable pH, and so many of the blue-flowered forms we tried ended up going reddish, no matter how much we tried to acidify the soil. The selection with the most promise is the mophead cultivar ‘Enziandom’, which has a reputation for staying reliably blue or violet. Hydrangea arborescens ‘Annabelle’ seemed like a good candidate for providing white flowers, but it flops horribly and requires staking. This plant just doesn’t seem to reach its full promise in the Northwest—even when its feet are wet, it wilts and burns when we have a rare 85-degree day.

The garden presented one physical problem that we attempted to solve with shrubs. Beyond the edge of a patio on the east side of the garden was a potentially ankle-twisting drop of five or six inches. A minor elevation change like this can be more dangerous than a larger one, since the eye doesn’t expect it. To mitigate this hazard, we added a low hedge of a yellow-foliaged yew, Taxus baccata ‘Dwarf Bright Gold’. (Beware: plants sold under this name often turn out to be T. cuspidata ‘Nana Aurescens’, which is overly sensitive to sun and dry air.) The idea is for this line of foliage, which is kept trimmed low, to sharply delineate the transition, so that people will notice the foliar color even when it’s dark. H

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