Creative Companions: How Companion Planting Increases Harvests through Natural Pest Control
We all know that certain foods taste delicious together, like basil and tomatoes. But did you know that basil and tomatoes grow well together, too?
Companion planting—combining different species of plants to benefit one another in the garden—is a long-practiced organic gardening technique. Remember U.S. history class? Native Americans grew food for a balanced diet in a single plot of land. By planting corn, beans, and squash together on a hill, they maximized their harvest in minimal space. The practice became known as a “Three Sisters Garden.” The plants proved mutually beneficial: the tall corn supported the climbing beans; the beans added nitrogen to the soil, providing nutrients for the corn; and the low-growing squash vines served as a living mulch, preventing weeds while retaining moisture.
Companion planting is a great way to pack lots of veggies into a small space, but it also serves many other purposes in an organic garden.
Companion Planting Deters Pests
Scent attracts many pests to their host plants. Insects lay eggs on the host plant, knowing that the plant will provide food for the newly hatched larvae. By interplanting strongly scented herbs and flowers among crops in the vegetable garden, pests become confused, leaving your future dinner in peace.
If you want to protect your harvest, try these companion plantings that repel pests:
- Garlic or garlic chives with roses: repels Japanese beetles and aphids
- Tomato with asparagus: repels asparagus beetle
- Radish with cucumbers: radish flowers serve as a trap crop for cucumber beetles
- Basil with tomatoes: repels hornworms and mosquitoes
- Nasturtium with squash: repels squash bugs
- Mint, thyme, and chamomile with brassicas: repels cabbage moth
- Border of thyme or lavender: repels slugs in the garden
- Onions with carrots: repels carrot fly
However, French marigolds win the prize as companion-planting champs. They deter Mexican bean beetles, aphids, potato bugs, squash bugs, and nematodes (microscopic roundworms in the soil that damage many plants). Plus, they add a beautiful burst of color to the garden. After all, an organic edible garden should be lovely to look at, too.
Companion Planting Attracts Beneficial Insects
Not all insects are bad. Along with repelling pests in the garden, it’s also important to attract beneficial insects. Beneficial insects serve many purposes. Bees, butterflies, and some beetles provide pollination, which increases harvests.
Besides pollination, many beneficial insects feast on pests, making your work easier. For instance, when you find a tomato hornworm happily snacking on your beautiful heirloom tomatoes, have you noticed small white spikes on its back? Those small spikes are actually killing the hornworm—organically. Parasitic wasps lay eggs on the hornworm, and as the eggs hatch, the larvae feed on the hornworm, eliminating your garden nemesis without an ounce of pesticide.
Nature is amazing, isn’t it?
As gardeners, we can minimize pests and eliminate pesticides by encouraging beneficial insects to visit. The trick is to know which insects are the good guys, and what plants to include in the garden to attract garden helpers.
Some beneficial insects include:
- Ladybugs: both the larvae and adults eat aphids, small caterpillars, and pest eggs.
- Braconid wasps: a parasitic beneficial insect, it lays its eggs on host insects. When the larvae hatch, they consume the host insect, killing it.
- Hover fly: larvae eat mealybugs, small caterpillars, and aphids.
- Lacewings: larvae eat aphids, small caterpillars and caterpillar eggs, small beetles, and insect eggs.
- Ground beetles: consume many pests, from asparagus beetles to squash vine borers.
How can you recruit an army of organic helpers to keep your garden pest-free? Adding flowering plants to your food crops attracts beneficial insects that will keep the pest population low, while also encouraging pollinators to boost your harvest. Plus, some of the recommended plants serve a dual purpose: attracting beneficial insects and providing flowers and food for you, too. A few recommended plants include:
- Queen Anne’s Lace
- Golden Marguerite
- Butterfly weed
- Lemon Balm*
- Also, allowing parsley, carrots, and celery to overwinter in the garden produces blooms the following year, which are attractive to many beneficial insects.
(*Plant mints and lemon balm (also a member of the mint family), in containers, as the plants can overtake a garden with their vigorous growth.)
Remember to include a succession of blooms so that beneficial insects visit your garden spring, summer, and fall—and winter in mild climates. Feed your flowers and crops with Espoma Flower-tone 3-4-5 to keep plants healthy and productive.
Companion Planting Increases Harvests and Improves Flavors
While we often think of companion planting primarily as a method of pest control, companion planting also improves harvest flavors—and even yields. For instance, in a limited-space garden, combining tall, sun-loving crops, like tomatoes, with shorter plants that enjoy a bit of shade in the heat, like lettuce, allows maximum use of space in a 4′ x 4′ raised bed. Add nasturtiums to your bed, and now you have beautiful, edible flowers to brighten your meals. Place a trellis for cucumbers along the back edge of the raised bed, and you’ve added another treat for your organic salad. The nasturtiums entice pollinators to visit, increasing the yield of your tomatoes and cucumbers, plus they serve as a trap crop for aphids, protecting your harvest.
Add a few radish seeds near the lettuce. Not only do radishes and lettuce grow quickly, but the lettuce protects the flavor of radishes in summer when they can turn bitter. Add a dill plant or two in the corner, and encourage braconid wasps to hunt tomato hornworms for their nursery. You’re protecting the tomatoes while growing an ingredient to add to a homemade salad dressing.
Perhaps you want to create a pretty, edible container garden. For a cool season combination, plant kale as a “thriller”—the central, taller plant in the combination. Add aromatic herbs, like sage, to protect the kale from cabbage moths as your “filler.” Finally, plant pollinator-friendly violas along the edge of the container as the “spiller.” The violas will tumble over the edge of the container as they grow, attracting pollinators and adding aesthetic appeal—and the flowers add a lovely, edible ingredient to meals.
Companion planting packs many benefits into a small space. It does require a bit of thought about your garden. What crops will you grow? What pests also enjoy the same food you do? Which plants can help you fight off the bad guys while attracting the good insects? The time spent planning your companion plantings is worth it. Adding beautiful, beneficial flowering plants into your garden plan is much tastier than eating a toxic dressing of pesticide on your produce, don’t you agree?
Besides, creating an organic garden filled with blooms is a beautiful way to eat healthfully while saving money, too. Enjoy!