Triads: Planting in Threes

Three is a popular number in many aspects of culture, including design. There are triads and trios in music, three-act plays, and triptychs in art. The "rule of threes" is a key principle in comedy.

In planting design, three is often considered a magic number. It's an easy way to think about planting for pleasing impact. In general, odd numbers are useful in creating dynamic, natural-looking plantings. (Rely on even numbers, such as pairs, for more formal effects.) If three of one plant doesn't pack enough punch, plant it in fives or sevens. Masses of a single plant catch the eye while plantings with lots of "onesies" and "twosies" can look jumbled or too fussy.

But some garden situations call for more than trios or quintets. When you're looking to cover serious ground or make a really big impact, create volume by massing dozens of the same plant, such as Lily-of-the-Valley. The eye ceases to grasp the actual numbers and instead takes in the sweep of a scene.

When reprising an element in a garden's design, try to repeat it at least three times. This holds true for both plants and hardscaping elements. You can repeat a color, a shape, or a specific plant, such as a series of three Hydrangeas as a backdrop for a border. Create a sense of rhythm in your garden by repeating elements with attention to the frequency. When in doubt, count to three.