COLOR IS MY JAM — more, please. But form, as in the shape of a leaf, the silhouette of a bloom and the overall profile of a plant, is the backbone of a successful garden design. Spires, spikes and skinny plants are some of my favorite forms to play with — possibly because tall, narrow plants have a relatively small footprint, so it’s easy to shoehorn them in among drifting perennials in early spring, just as established plants are putting on new growth. More plants are always good.
In “Designing with Plants,” European plantsman Piet Oudolf writes, “Spire-shaped flowerheads lift the garden.” By drawing our eyes upward, plants with a narrow profile fill the space above the garden, making even the tiniest planting bed feel more dynamic as the spires catch the breeze. The master designer goes on to advise planting spires and spike-blooming plants in multiples, never as a lonely single.
I first planted rusty foxglove (Digitalis ferruginea) many years ago, and it continues its lazy meandering way through my borders, shifting about from year to year. Like common foxglove (D. purpurea), rusty foxglove is a biennial or a short-lived perennial that seeds about after blooming. But while the tall stems of pink, white and purple blooms of common foxglove take to the shade, rusty foxglove comes out of the shadows, lending a strong vertical accent to sunny beds and borders.
Emerging from an evergreen basal rosette, in early summer, rusty foxglove sends up dark maroon stems that grow 3 to 4 feet tall, clothed with glossy narrow foliage. But the best part is when the densely packed spires begin unfurling small, lipped blooms in shades of yellow, cream and orange delicately veined in maroon. At a distance, the effect is that of a burnished coppery brown. The blooms are especially beautiful when backlit and framed by transparent grasses or in the company of similarly colored blooms like Geum ‘Totally Tangerine’. Or pair with Geranium ‘Rozanne’ to create a dazzling complementary color companion.
Bees and hummingbirds are attracted to the nectar-rich blooms of rusty foxglove. As the flowers age, they are followed by dark brown, almost nutlike seed heads that carry interest into the fall and winter, and feed the birds. Rusty foxglove also makes a good cut flower in an interesting color palette — just be sure to leave a few bloom spires standing to ensure future blooms.
Plant rusty foxglove in partial to full sun, and provide well-drained soil. After a typically wet spring, I don’t water my plants much, if at all, over the dry summer growing season. But after the dry spring we just had, you might find that you need to provide supplementary water to low-water plants to get them through our dry summer.
In addition to levity and movement, some of my other favorite vertical plants, like tall vervain (Verbena bonariensis), drumstick allium (Allium sphaerocephalon) and ruby orach (Atriplex hortensis), are also low-maintenance, effective players in the four-season garden. Like rusty foxglove, these plants are independent self-seeders that always seem to know where to best insinuate themselves about the garden, lending spontaneity to naturalistic garden compositions. And if they land where they’re not welcome, simply weed them out, or transplant young plants to a new home.