What are the fundamentals of design when it comes to using perennials in the garden? There are tangible components of garden design, such as hardscape and water features, and there are intangible features, changeable components such as the quality of the light and the shape of a plant because of weather conditions or growing aspects.
The first consideration in your garden design should be you. How do you move about the garden? This determines pathways and patios—the so-called hardscape of the garden. Once you know where the plants won’t be, you can think about how to use them where they will be.
Gardens—other than their hard surfaces of stone and brick—are alive, and therefore we can’t design them as we can a living room or bathroom. Not that we don’t try, of course. Books and magazines are full of garden plans that you can copy. But even in the most well-laid garden plans, plants happen.
The overriding factor in designing with perennials is where to put the plants so that they will be healthy, because healthy plants are good-looking plants. Not only is a healthy garden a beautiful garden, but when you make good choices of plants and placement, your garden will result in less work and fewer problems. And if you have to spend less money on water and controls for pests and diseases, you will have more money for buying plants. Works out well, don’t you think?
Get to know the specific characteristics of the different areas in your garden so you can create a design that pleases you. This is not difficult. Rather than focusing on which colors to combine, begin with reading the cultural notes for each plant!
For instance, you love hardy geraniums but think that they grow only in full sun. However, the mourning widow (Geranium phaeum) appreciates part shade, and the evergreen Geranium macrorrhizum takes even dry shade. Or say you love agaves, but your garden is mostly shady. Then you’d better love agaves in pots, so that you can set them on the driveway against the south-facing garage door.
Avoid combining plants with contrasting cultural needs, because this leads to stressed plants that are susceptible to problems—and then there goes your perfect design. For example, if you can’t do without a water-loving astilbe in a shady location, combine it with Rodgersia—another shade plant that needs regular water—rather than Epimedium or hardy cyclamen.
You don’t have to fill your head with rules when you decide where to put plants—you probably use design concepts without thinking. So consider the following sections simply as guidelines. If you have the space and if yours is a new garden, you can move nursery pots around the area, stand back, and squint (which helps you imagine the plants all grown up) to see if you like your choices.
giant scabiosa (Cephalaria gigantea)
The elements of design—whether for gardens or any other composition—include these components:
• repetition
• variety
• balance
• emphasis
• sequence
• scale
Running as a common thread through each of these design elements is a subset of characteristics that include:
• line
• form
• texture
• scent
• color
The design elements and their characteristics are not separate unto themselves; rather, their importance and their use overlap and blend together. Here are some ways to use these design elements and their characteristics with perennials in the garden.
Repetition and variety would seem to be design elements that are at odds with each other, but actually each can be used to balance the other’s impact. Repetition of specific plants helps unify the garden and keeps it from looking like the multicolored sugar sprinkles on top of a cupcake. But far on the other hand, repeated ranks of the same plants can begin to look like a public landscape—and you don’t want your garden compared to parking islands at the mall.
The middle ground is to repeat the same plant occasionally but also to pick up on its color, form, or texture and repeat that characteristic throughout the garden for variations on its repeated theme. For instance, to repeat the low, hummocky form of Geranium macrorrhizum, use the rounded form of lady’s mantle (Alchemilla mollis). Or repeat the pink flowers of Linaria purpurea ‘Canon Went’ (toadflax) in early summer with the pink show of Aster ‘Andenken an Alma Potschke’ in late summer—and both are tall and thin, which repeats not only the color but the form, too.
The preceding example shows how the elements of design overlap: In addition to being a means of repetition, color and form also have much to do with emphasis in the garden. A contrasting spot of yellow draws the eye. Accent a particular area with the tall, upright form of Verbena bonariensis.
Perennials and Hardscape
Whether your garden came with existing hardscape—fences, walls, patios, and paths—or you are designing your own placement, you can use perennials to accentuate, soften, and integrate the structures. Take, for example, the intersection of two concrete paths. For a formal look, plant a small catmint (Nepeta ‘Little Titch’) in each of the four 90-degree angles of soil. If these seem too blousy, fill in the corners with small, compact mounds of thrift (Armeria). At the base of an arbor, plant a Geranium renardii to hide any necessary fixtures for the structure. Call attention to a piece of stained glass set into a gate by planting a perennial that blooms in the same color. Perennials are much easier to move than a concrete patio, so use plants to help maintain or change a look, before resorting to the sledgehammer.
thousand-flowered aster (Boltonia asteroides ‘Snowbank’)
The succession of flowers described in the toadflax-and-aster example also shows how sequence can be integrated into your garden design, which can change the impact of emphasis as well. The ebb and flow of different parts of the garden through changes in foliage and flowering over time yield emphasis now here and then there.
What Color Is Your Garden?
Colors go in and out of style in the garden just as they do in clothing or refrigerators. Orange was hot then passé. Pastels and blues were in then boring. Everyone needed a white garden, and then they didn’t. It became important to have all the same color, but in graded tones, then that seemed too fussy. But savvy gardeners have come to realize that it’s personal preference in color that matters, not a sense of fashion. If you prefer precise complementary and contrasting colors, find a color wheel and go to it. If subtle is your middle name, plant a garden with all blue flowers. Play fruit-basket mixup with pinks and purples, scarlet and yellow. Then live with it a while before you decide to do something different.
The element of scale involves the impact of your house and other buildings on your garden design. Large, lumbering shrubs overwhelm a tiny house and garden. A landscape with only dwarf, rock-garden plants looks like it was designed for a Barbie doll. Use a variety of plant sizes to ensure that the plants neither over- nor underwhelm the site.
These design elements must be fit into your own space. No one can tell you what to do (unless you hire someone to design your garden for you). Magazine and book designs, with their neat little blobs of color here and there, all correctly labeled, don’t translate well into every single garden. By all means, try such designs on for size, but be ready to substitute plants and placements when you discover that there are no cookie-cutter gardens.
Foliage—striped, blushed, edged, mottled, or downright saturated—is big in perennial gardens these days. To some, it’s the height of good taste; to others, a green leaf stippled in yellow looks diseased. For those gardeners who fancy it, variegated and colored foliage add not only interest to a garden or container but also can carry on a plant combination far longer than flowers.
However, as with every fashionable thing in this world, too much of a good thing loses its impact. Instead of going overboard on the variegation, be conservative. Judicious use of variegation makes a plant stand out against a quieter background. It’s much more effective to use one variegated plant in a sea of green and flowering plants than to have the entire scene taken up with it.
For example, the cream-edged leaves of the variegated wallflower Erysimum linifolium ‘Variegatum’ blend into the scene if planted alongside Carex morrowii ‘Variegata’. You’ll end up with zebras on the brain. But take the wallflower and plant it with Bergenia ‘Appleblossom’ and some black mondo grass, and the variegation pops out, providing a powerful punch.
The elements of design can be used in any garden style, and perennials—with their huge variety of forms, textures, flowers, and growing habits—fit into any garden style. Below are some of the more common styles.
lamb’s ears (Stachys byzantina)
• Cottage garden, an informal style full of perennial and annual flowers.
• Formal garden, where the outline is distinct and straight and where hard lines are softened by plants.
• Naturalistic garden, in which sweeps of plants are important, as are ornamental grasses, color tones come not just from flowers but also from foliage as it changes season to season. The naturalistic style is a movement that has come to the United States from Europe.
Which is your style? You may admire the strong lines of a formal design but prefer to relax amid an informal stand of foxgloves and hollyhocks. You may find bunches of ornamental grasses a tad too wild and long for straight lines with geraniums billowing into the paths. Visit many gardens and figure out what you like. Once you have determined which garden style you prefer, choose and combine plants to suit.
The mixed garden is a joy. Trees and shrubs provide those all-important “bones” to the garden—structure that carries through year-round. In winter, the mixed garden is not a wasteland of dead stems and seedheads (as important as those are for birds); instead, trunks and branches take center stage, with some winter blooms as accents for emphasis.
For example, a carpet of hardy cyclamen (Cyclamen coum blooms in winter) under the shaggy stems of an oakleaf hydrangea is a hearty sight in cold weather and stresses both variety of form and sequence of flowering.
Perennials need these partners in the garden in summer, too. It helps them to show off—employing the design element of emphasis. As a backdrop, the leafy greenness of nonperennial companions sets off colorful perennial flowers and foliage; the companions provide shade as well as a frame.
Hedges—short or tall—offer a good green curtain for perennials. For instance, Japanese holly (Ilex crenata) includes cultivars with a year-round clean look, such as ‘Helleri’ (to only 3 feet) and ‘Jersey Pinnacle’ (to 6 feet). Boxwood, another example, is the classic choice; use a row of the low English boxwood (Buxus sempervirens ‘Suffruticosa’) to line a bed or walkway, setting off the flowers and foliage within. Or choose a flowering evergreen shrub such as Escallonia for its greenery and for its small clusters of rose-pink flowers late into the year; this employs the element of sequence.
Designing, with Perennials in Pots
Perennials can live for years in containers if given the proper care, so feel free to decorate your patio, balcony, or deck with them. You can combine perennials with woody plants in large pots, but remember that trees and shrubs may eventually need to be planted out in the garden. Here, just as in the garden, it’s important that you group plants according to their needs; no sense in overwatering one plant and underwatering another when they are in the same pot.
There are no approved and disapproved lists of perennials for pots. As long as you care for them properly, all will live long and prosper. Some plants you may want to particularly choose for pots—the aggressive ones. If you don’t like the thought of Mrs. Robb’s spurge (Euphorbia amygdaloides var. robbiae) expanding its territory in the ground yet you like its evergreen appearance, keep it in a pot.
Pots are perfect for decks, patios and front entrances. They soften hardscape, but also dress up the scene, especially when you choose attractive containers. Large containers can stand alone, but small containers look best when grouped for effect. Cluster pots of perennials in opposite corners of the deck or patio. This gives you the opportunity to spotlight perennials in bloom, and reorganize the pots for another, later show. Use one large pot and two or three baby pots at its base for a front-door arrangement—if it’s in the sun, you could choose tall and short bearded iris. Plant a formal concrete urn with short varieties of sedum or billowing soapwort. Place single, tall pots within the garden to give height to a bed, and add something spiky such as Crocosmia or Schizostylis for drama.
primroses (Primula)
spurge (Euphorbia griffithii ‘Fireglow’)
Shrubs and small trees play a part within the mixed garden, too, for emphasis and protection from weather. For instance, the deciduous shrub Enkianthus campanulatus is a piece of architecture: It grows stiffly upright but its branches grow on a horizontal plane, providing contrast to mounding or short, spiky forms below it—variety of form. Its small leaves don’t throw too much shade, and so beneath its branches you can place perennials that need sun to part shade and that tolerate slightly acid soils—lungworts, for example.
Light and airy shrubs fit well into the mixed garden. Consider, in a sunny spot, a combination of the small mock orange Philadelphus ‘Belle Etoile’, ground cover roses with Oriental poppies, and viburnums with asters. For part shade, try the royal azalea (Rhododendron schlippenbachii) and the buttercup hazel (Corylopsis pauciflora) with lungworts (Pulmonaria).
Maintaining a particular design by keeping tight control of a landscape may be possible in a public garden or a historic garden, but home gardeners don’t have the time or the staff for such an effort. And when another homeowner moves in and gets used to the garden, then it’s time for a change. Garden designers of the eighteenth century created composed landscapes made to look like paintings, but even their composed settings aged and changed. Ultimately, we should be ready to reconnoiter, reorganize, redesign, and replant.
Plants grow up; for instance, phlox can expand its holdings until it takes up twice the space it started with. Plants that increase in girth can be divided (see Chapter Three), but a stand of Siberian iris makes a formidable impression, so don’t be too hasty to chop plants up into smaller bits of plants just because you think you should. Mature gardens, with plants amiably jostling elbow to elbow, give a pleasing, bounteous look; perennials growing with lots of space between them can look like a scientific experiment.
Perennials have variable life spans; they may edit themselves out of the garden because of conditions or because of their own genetic makeup. For example, some plants, although they continue to bloom, never set any seed—which, for a plant, is the whole point of blooming; these plants can bloom themselves to death. You can decide to replace such a plant with another identical species, find a different plant for the space, or let neighboring plants fill in.
The wallflower Erysimum ‘Bowles Mauve’ is just such a plant. It quickly makes an impressive 3-foot mound of bluish-green foliage and begins blooming almost immediately. Clusters of deep mauve flowers appear on narrow stems. The flowers keep coming, sometimes all year in mild Pacific Northwest winters. Then, after about three years, you see a stem die off. Within a short period of time, the plant either dies off completely or you wish it would. You didn’t do anything wrong. It’s the nature of the plant. You can replace it with another ‘Bowles Mauve’ or not.
Plants that set seed can be a boon and a bane at the same time. On the plus side, they self-seed new plants all around them, saving you the task of planting, but on the negative side, these volunteers may grow where you don’t want them.
For instance, the maroon-black flowers of Knautia macedonica are on long, flexible stems that lean this way and that until they weave several plants together into the scene. It’s difficult to cut back these interwoven flower stems that still have flowers opening high up on the stems, so old flowers farther down the stem begin setting seed and Knautia reseeds from these. In two years, one plant can increase to several, forming low, wide rosettes of leaves that tend to muscle out small plants. But because it’s a plant that looks better with neighbors close by, rather than being alone in a spot where it merely flops, you must choose where to let it self-seed. In late winter, it’s easy to decide which Knautia plants to leave and which to remove. A little help with a hand cultivator or digging fork, and the plant pops out of the ground.
The trees and shrubs in the mixed garden do their part in changing the design of a maturing landscape. A birch tree grows up; a mock orange gets middle-age spread. What was once a sunny terrace now has dappled shade from the expanding plum tree.
Or a much-loved flowering cherry has died and now the woodland garden is a desert. Blazing full sun doesn’t suit a plant such as delicate meadow rue (Thalictrum), chosen for the shade of a now-missing tree, and the sudden change between shade and sun can wreak havoc on even those plants that might grow fine in full sun if they’ve grown accustomed to it slowly.
Ultimately, whether trees and shrubs grow larger, increasing the shade beneath them, or are removed for whatever reason, suddenly eliminating the shade they once provided, your perennials may need moving too. Perennials, by and large, are an accommodating bunch when it comes to transplanting. They’d rather be moved than put up with adverse conditions. So be prepared to change your garden design as your garden evolves.
gaura (Gaura lindheimeri ‘Whirling Butterflies’)
