Why do we like to see things in threes?
It’s because three is easy. It’s the first pattern the mind can process, and the brain is eager to connect dots into patterns. One dot could be a random accident, two might be a coincidence, but three is a pattern, and suddenly we are interested.
Yet there may be more to the magic of threes, a fun aspect to consider in the garden. A threesome becomes a triangle when laid out spatially, and it’s likely that this layout is pleasing to many plants compared to growing singly or in mass. The intermingling of roots, branches and blossoms benefits the triangular clump without the risks that come with overcrowding. In one of the most classic methods for growing squash, for example, seeds are sown in raised hills and thinned to three per hill.
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Three different colors and textures bring a pot of lettuce to life
Planting in Threes in Containers
Plant trios also look nice, and they are the most common way to compose attractive containers. Whether in a bed or a vase, floral designs comprised of an upright ‘thriller,’ a fine textured ‘filler’ and a cascading ‘spiller’ plant are open to endless interpretation, and it’s an easy guideline to follow.
It’s also hard to go wrong by combining three different colors of the same plant. With seedlings that echo their mature colors in their stems, for example marigolds, chard, and some cosmos or zinnias, you can compose a color-balanced trio at the pricking out stage and then move the grouped seedlings to roomier containers or the garden, where they form their own bouquet of color.
Anytime you want to refresh the look of your container garden, simply rearrange your pots into threes or fives, the brain’s next most favored number.
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Basil seedlings thinned to three plants per pot grow into robust clumps in the garden
Ecological Benefits of Planting in Threes
Let’s say you want to grow basil, marigolds, or other flowers to confuse pests and keep pollinators happy. In addition to being easier for insects to see, clumps emit a stronger scent trail, so it’s always a good move to set out trios of your favorite companion plants.
Multiple flowering plants also are more attractive to pollinators because they can feast on many blossoms at one time without wasting energy flying around. To bees and butterflies, three cosmos are always better than one.
With plants that are grown for their seeds, three plants is often the minimum number needed to ensure good pollination. For example, three dill plants grown together share windborne pollen and are further cross pollinated by visiting insects, resulting in a heavy crop of tasty seeds.
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Three arugula plants being grown for seed share a common trellis
Seed-bearing plants that need to be held upright for a long time like arugula, cilantro, and dill are good candidates for growing in threes. Once they reach the flowering stage, a cluster of three plants can share support from stakes, cages or other trellises, keeping the seedpods high and dry until they ripen to tan.
Tall Timbered Trios
Plants that look most impressive when grown in a small mass, like sunflowers and tall zinnias, are great plants for growing in threes. When three tall, lanky plants are grown together on a shared trellis, their untamed nature assumes the presence of a symmetrical shrub. It’s my favorite way to grow sunflowers, tithonia (Mexican sunflower), and wild and crazy tomatillos, which like to grow into a tangled mess.
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Butterflies are drawn to a trio of tithonia (Mexican sunflower)
Three is so well represented in math, design and even religion that you can’t knock its significance. As you pot up your seedlings and set out your starts, it’s comforting to know that something as simple as the number three can help you grow a better garden.
