Choosing Plants for Flowerbeds & Borders
Be generous when marking out the area for your bed or border. If you can afford the space, allow at least 10 ft (3 m) to provide a good planting width. You can then build up several layers of plants, one behind the other, and use shrubs and climbers to create height toward the back. If the choice is between two narrow borders and one deep one, you’ll find the larger more rewarding, however intimidating it may seem at first. Key plants, such as tall wispy grasses, add focal points to borders and beds. Structural foliage plants are useful inclusions as their impact is more enduring than transient flowers.
Choosing the Key Plants
Working from an accurate base plan makes designing a new bed or border easier, and helps you decide how many plants you need to fill it. When selecting plants, think of your border as a stage performance, and pick out the leading cast. This should include plants that have an important presence because of their handsome shape, decorative leaves, or long flowering season. Good candidates include colorful foliage shrubs, such as berberis and cotinus, and many of the grasses, sedums, and euphorbias. Repeating these every few yards brings rhythm into a plan.
Think of where you would like to see your stars: sedums flower in fall and are good front-of-the-border plants, while taller grasses, such as molinia or calamagrostis, are better placed in the middle or background. Mark the plants on your plan with a circle representing their final spread. Most of the larger perennials will spread to 18 in (45 cm), while smaller ones will reach 12 in (30 cm); check plant labels for the spreads of shrubs, and note that their size can be affected by your soil and garden conditions.
Planning in Color
Once the key plants are on your plan, choose supporting players that offer more subtle effects. Keep a note of their flowering times and colors, and, if in doubt, make an overlay with tracing paper, onto which you can mark the color of each plant using different pen types or symbols. Do a few overlays for the different seasons to show when your chosen cast is in flower, where the gaps are, and at what time of year they need to be filled.
Contrasting Flower Shapes
Think of the contrasts in flower shape as well as color, height, and season. Plants with spiky flowers, such as veronicas, delphiniums, foxgloves, and verbascums, or upright, linear foliage, such as irises or daylilies, will introduce a vertical accent. Those with round, disklike flowerheads, such as sedums, yarrows, fennel, and all the cow-parsley relatives, create a horizontal plane. Mixing these two types of flowers paints an exciting picture. Distinctive spherical shapes, such as alliums and Echinops ritro, add to the structure.