The idea behind companion planting is that plants can benefit each other when they’re planted together. Plants can provide nutrients for each other, attract beneficial insects to nearby plants, deter unwanted pests, and provide a “living mulch” by suppressing weeds and helping to retain moisture. Knowing which plants to plant together can help you gain more productive crops, as well as help you practice organic gardening and organic pest control.

Gardeners used companion planting for nutrients and pest control before the development of fertilizers and pesticides. People probably learned the art of companion planting soon after learning the art of gardening. In “The Gentle Art of Raising a Garden,” Liz Hancock writes that “slowly, over time, the secrets of what plants to grow with what and at what time and in what place would be passed on.”

You may have learned about some companion planting ideas from older generations in your family.

For example:

• Onions and leeks keep the carrot fly away from carrots.
• Basil and Borage are good companion plants for tomatoes.
• Garlic will help keep away all kinds of pests when planted throughout the garden.
• And you may have heard of the “Three Sisters”: corn, beans, and squash. Corn supports the bean vines; beans supply nitrogen to the soil; and squash prevents weeds and retains moisture in the soil.

How Does Companion Planting Work?

One way in which companion planting works is by smell. In Companion Planting, Kris Wetherbee writes that “many pests locate their next meal by the scent it emits.” For example, the cabbage moth is led to cabbage and broccoli by their scent. Having carrots and onions surrounding the cabbage and broccoli will help throw off the cabbage moth from the scent trail. Some plants like Marigolds and Garlic have such strong odors that they can deter many pests from neighboring crops.

Some plants contain chemicals that can actually harm pests. Plants that contain mustard oil can sicken or kill pests such as spider mites and Mexican bean beetles. Mustard oil is in cabbage, kale, cauliflower, Brussels sprouts, and broccoli–making these good companion plants for beans.

Another way companion planting works is by touch. Some pests don’t like the feel of certain plants, so you can surround a pest’s favorite plant with plants the pest does not like. Try planting scratchy or thorny plants to deter rodents from crops.

Plants can also attract desired insects to crops. Insects that eat undesired pests are considered “beneficial insects. In Plants that Attract Beneficial Insects, “Farmer Fred” Hoffman writes that we can attract “good bugs” to our garden by planting their favorite plants.

Lacewing larvae feed on aphids and mites.

Some plants that attract lacewings:

• Dill
• Angelica
• Cosmos White Sensation
• Queen Anne’s Lace

Lady bugs and their larvae eat aphids.

Some plants that attract ladybugs:

• Common yarrow
• Butterfly weed
• Carpet bugleweed
• Rocky Mr. penstemon

Other insects are beneficial because they help pollinate the flowers. To learn how to attract butterflies, visit …

And don’t forget that birds like to eat pests too. Try growing sunflowers, purple coneflower, and pincushion flower to attract birds that like seeds. Grow salvia, hibiscus, and columbine to attract hummingbirds.

How Do You Begin Companion Planting?

In “Fruit Trees and Family Friends,” Lauri Newman writes that we should begin by choosing the main crop. Then choose “family friends,” which are plants that add nitrogen and nutrients to the soil; deter unwanted pests and diseases; help prevent weeds and retain moisture in the soil; and attract beneficial insects for the main crop. Plant the main crop in the center and the family friends around it.

For example, let’s say that you plant an apple tree.

Companion Plants for Apple Trees

First determine a location for your apple tree. Then, select companion plants to surround the tree.

You’ll want some companion plants that provide nitrogen and nutrients to the soil.

Some plants that supply nitrogen and nutrients to the soil:

• Chamomile
• Beans
• Peas

Next, choose plants that deter pests and diseases.

Some plants that deter pests and diseases:

• Marigold
• Nasturtium
• Pansy
• Chives (especially good for apple trees because they help prevent scab)
• Garlic (also good for apple trees because they help prevent scab)
• Borage

Next, choose some plants that will attract beneficial insects.

Some plants that attract beneficial insects:

• Sweet alyssum
• Dill
• Clover (especially good for apple trees because they attract insects that eat the whooly aphid)

And then ensure that you have a “living mulch” around the tree.

Some plants that serve as a mulch:

• Comfrey
• Clover
• Alyssum

(Note that many of these plants provide multiple functions in the garden.)

Companion planting can help provide a healthy environment for your plants, as well as a healthy environment for people, wildlife, and the planet.

by Shannon Mendez