Our agricultural ancestors discovered long ago that when some crops were planted near others, each thrived more than the same crops planted apart. Thus was born the art of companion planting. Companion planting is a long-standing practice in gardening and farming because diversity in the garden is essential to happy, healthy plants.

Companion Planting is Easy

This is where garden planning meets art and design; where growing food connects to biodiversity and beauty; where nature benefits practicality. A good time to start is when you’re planning your Spring garden.

What flowers, herbs, and other plants are good companion plants? While there are many old adages like “carrots love tomatoes” and “marigolds love squash,” the science behind companion planting can be confusing and contradicting.

Rather than giving you set rules stating, “this goes with that,” we take a simpler approach, using the following two guidelines to help your planning.

1) Diversity is Key

The more diverse your garden is, the less likely one particular disease, pest, or pathogen can come in and wipe you out. Diversity in planting also brings habitat for beneficial insects, which helps to keep an equilibrium in your garden between the good insects and the not-so-good insects.

2) Do No Harm

When considering planting things near each other, ask yourself, “Is putting this plant here going to harm its neighbor?” What do we mean by harm?

• Is one plant going to shade another? Shade can be beneficial or harmful. For example, corn grows tall, so you wouldn’t want to plant other sun-loving crops in the corn’s shade. But other crops, such as squash, enjoy the corn’s shade; in turn, the squash’s broad leaves keep the soil cooler, which is good for the corn.
• Are plants going to compete for space or moisture in a container? Generally speaking, vegetables and flowers need more water than herbs, so putting them all in the same container may not work out. Some plants, like squash, grow big and like to sprawl, easily crowding out other plants. But if you plant a tall growing companion to your squash, such as pole beans, they won’t compete for space and light.
• Do the plants have similar watering requirements? All plants need ample water when growing stems, roots, and leaves during their vegetative stages. Some require ample water during their full productive run, but others do better when water is reduced during production (tomatoes) or turned off entirely while finishing (onion, garlic). It’s important to keep this in mind when designing your garden and irrigation system. Do your best to combine plants with similar watering needs in common irrigation zones.

Favorite Companion Plants for Tomatoes

Marigolds

• Compact plants do not compete.
• Research suggests they repel aphids.
• Attract beneficial insects.
• We love the flowers!

Alyssum

• Compact plants do not compete.
• Create a living mulch, holding in moisture and inhibiting weeds.
• Attract beneficial insects.

Calendula

• Compact plants do not compete.
• Attract beneficial insects.
• We love the flowers!

Do Not Plant These Flowers with Tomatoes

Morning Glory

• Their roots strangle tomato roots.
• Compete for space and light on the trellis.

Sunflowers

• Tall plants block sunlight.
• Compete for moisture in containers.