Combining plants well requires both skill and artistry.

You're wandering through a plant shop, or paging through a catalog. What strikes your fancy? Chances are, you're attracted to the dramatic plants: variegated foliage, brightly colored, large flowers or leaves, unusual shapes and textures and color combinations.

But chances are equally great that, if you took all the plants that appeal to you and put them into a garden, they wouldn't make an appealing composition. That's because they're the stars, and to really shine, they need a supporting cast.

This is a common but useful metaphor. Your landscape should offer focal points, and dramatic plants make great ones, but too many focal points overwhelm and agitate the viewer. Your eyes should leisurely float through less differentiated foliage, and every so often encounter a focus that arrests their movement and induces them to examine it more carefully. How often this happens is up to you, and your choice determines your landscape's place on the continuum from relaxing to lively.

Just as combining many beautiful melodies doesn't make a lovelier song but rather a confusing cacophony, so your garden must stick with a main theme. If you force it to hold all the beautiful things you can dream up, it risks becoming a visual cacophony.

Choose a few main focal plants. Find background plants that set off their dramatic qualities by providing a contrast with one or more of the key plants' most noticeable features. For instance, say you have a large-leaved plant such as hosta 'Sum and Substance'. The leaves are bright gold, large, glossy ovals with heavy veining. The form is vaselike, rising up from the ground and then spreading out about a foot or more above it. What will display it to best advantage? A background plant (or plants) with leaves that aren't gold, aren't large ovals, and take up a different vertical plane.

I've used lady's mantle (Alchemilla mollis 'Thriller'), which has matte, blue-green, furry, ruffled leaves and gold sprays of flowers that rise above the prostrate rosette of foliage. The leaves provide a complete contrast to the hosta in shape, color, texture, and vertical plane. The flowers provide a partial contrast—their delicate sprays are a much different shape and texture than the leaves of either plant, and yet they echo the color of the hosta leaves, which ties them to the other plant much more strongly than a full contrast would do.

To round out the combination, choose a plant that contrasts with both of these: I chose straw foxglove (Digitalis lutea). It sends up stalks from a basal rosette of narrow, long, pointed leaves. The pale yellow flowers occur at intervals up the stalk, which extends one to three feet above the leaves. The flower color echoes the gold of the hosta leaves and the lady's mantle flowers just enough to tie them together. The foxglove leaves are a golder green than the lady's mantle and carry striations that subtly echo the hosta's bolder ones. The shape (tall and narrow) provides great contrast with the mounded forms of the other two plants.

This combination appeals throughout the growing season because the elements that provide contrast and echo change over time. The hosta leaves emerge in spring, and they steal the show for a couple of weeks, first emerging as rolled spears, then lengthening and gradually unfurling. Their color is so bright that it catches the attention first.

But the lady's mantle has been building full, furry sets of leaves, and when they hold droplets of water, they're arresting. It starts to flower after the hosta is in position, and the flowers emphasize the scene though they don't really call attention to themselves. This is the way of billowy masses of flowers, to enhance the bold spots of color without claiming any notice. They're the perfect type of supporting cast, egoless and effective.

The foxgloves meanwhile are sending their stalks up, and budding, and finally their flowers open, bottom flowers first, and over a couple of weeks the higher flowers open as the lower ones fade, while the lady's mantle keeps blooming, and this is the season in which the combination puts on the most lively show and seems to fill out the space most completely, with the hosta forming an eye-catching gold wall against which the other plants move and change.

After the foxgloves have finished blooming, their tall stalks remain, waving above the lush lady's mantle whose sprays of flowers turn crisp and brown a couple of weeks later. The lady's mantle and foxglove basal leaves continue to cover the ground through fall, then turn brown in winter and remain until they're eclipsed by fresh new leaves.

Each year, this combination improves as the component plants (all clump-formers) expand to cover the space between them without smothering each other. The key is to give each plant enough space at the beginning that it can expand happily without crowding. Plant sizes vary according to soil and climate, so my spacings may not work for you, but here they are.

I kept about a twelve-inch circle free around each hosta and lady's mantle plant. The hosta will spread wider, but it rises above the ground while the lady's mantle hugs the ground. Older lady's mantle plants will produce smaller attached plants around its edges, and you can detach these and plant them elsewhere in the garden if they start to crowd their neighbors, but I tend to leave them so I get good thick coverage that inhibits weeds. I give the foxgloves about six to eight inches of area in which to spread, since they mostly grow upward. One spacing issue in this combination is keeping the foxgloves a couple of feet away from the hosta so its large high leaves won't push over the foxglove flower stalks.

The number of each species will determine the effect of each plant against the others. My little vignette includes one gold hosta set among two dozen lady's mantle and a dozen floxglove in a woodland clearing at the foot of two birch trees. The foxgloves are clustered near the tree trunks while the lady's mantles flow around them and the hosta, which I placed off to one side. The balance produces an understated effect that I find beautiful, but different numbers of the same species could be used to achieve several different effects.

That's a detailed account of how I created a most satisfying combination of plants. I hope you'll be inspired to choose a few plants and try it yourself!