Adapted from Ann Lovejoy's Organic Garden Design School, by Ann Lovejoy.
An informal rule of thirds makes for pleasing garden combinations. The thirds refers to plant types. Many gardens can suffer from one of two extremes: they are short on structure and long on seasonal color or they are long on structure and short on seasonal flow. Striking a balance between structure and seasonal interest should be one of the goals of a naturalistic garden.
Here is the rule of thirds—and an interesting and insightful new way to look at your garden:
One third of the garden's plants are evergreen.
The author uses the evergreen third to integrate the garden with its setting and to create patterns that hold the garden together during the winter. These evergreens are part of the garden's bones; they establish the lines and flow of the garden from within the house, from within the garden itself, and from outside of the property.
Another third of the garden is structural deciduous plants.
These plants are less visually dominating than the evergreens, but they are still powerful in form and line. Small deciduous trees or large shrubs are the largest plants in the category; they should nearly always be sited for maximum winter effect. A graceful, fluid shrub or a small tree, such as a flowering dogwood or a cascading weeping cherry, can soften the naturally stiff and unchanging evergreens when flower petals drift onto the evergreen branches.
Small deciduous shrubs (such as the colorful border barberries, compact spires, and shrubby potentillas) may lack leaves in winter, but their densely twiggy structure holds power even when bare.
The final third of the garden consists of seasonal color plants (bulbs, perennials, and annuals).
These plants bring a vital sense of change and liveliness to an otherwise static garden scene. Though their beauty is ephemeral, perennials in particular may be considered the lifeblood of bed and border.
When considering perennials for inclusion in a garden, always evaluate them for their overall contribution, not simply in terms of what color they bloom and when. Many perennials have little intrinsic architecture, while others offer a handsome shape and attractive foliage, as well as beautiful blooms