Companion Planting Basics

For some, planting a garden is as simple as visiting a garden center, buying some plants, taking them home and putting them in the dirt. Sometimes the dirt is in a pot or a raised bed, but sometimes it's straight into the ground. Then they water them and that's it. For other gardeners, soil type, amendments, fertilizers, soil PH, and even the soil microbiome are considered. The longer you garden, the more you can teach yourself about all of these, as well as natural pest control, weather, wind and humidity changes, common diseases and of course: companion planting. It's the difference between your plants living, and your plants and mini garden ecosystem thriving.

In a previous blog post, I talked about the importance of pollinators, so we already know that having flowers, herbs and other blooming plants intermixed near our gardens is essential not only for the well-being of our crops, but the well-being of the planet. But there is also magic that happens many inches below the surface of your soil, you see, some plants can act as natural pest repellent, while others act as “trap crops” to attract those pests so they stay away from more important or delicate plants. Some crops will preferentially drain the soil of a specific nutrient, while others will put specific nutrients back into the soil for the benefit of other plants around them. Here in lies the foundation for companion planting, so let’s dive in to some very basic companion planting options for some of the most common vegetable, herb and flower crops for backyard gardeners.

Let's start with my personal favorite, the nightshades (tomatoes, peppers, potatoes and eggplants). Nightshades appreciate balanced nutrients in their soil, and tomatoes in particular need a fair bit of calcium and magnesium. But they are also prone to certain diseases and pests. So, to fend off the attacks from white fly and aphids, plant some Basil with your tomatoes. Marigolds are an excellent choice with tomatoes for two reasons: they repel white fly and can bring in pollinators to make sure your tomato flowers get pollinated. Likewise, Borage will bring in pollinators and may enhance the flavor of your tomatoes (although this is just anecdotal).

Onions, garlic, leeks and other alliums are valuable friends to tomatoes (and just about all other crops as well) due to their fragrant nature. I tend to plant some garlic bulbs in each of my raised beds to help through pest off the scent of my other more prized plants, and if you let them flower, they are actually quite popular with a huge variety of pollinators.

Leeks work particularly well with carrots for a similar reason. Both have plant specific pests that the other helps repel: carrots help protect allium from onion flies and leek moth, while leeks repel carrot rust flies. Sounds like a perfect partnership, right? Likewise, leeks and onions are once again known in gardening circles to improve the flavor of and get rid of bugs that like to munch on celery.

One friendly situation that you may already be familiar with, is commonly known as the “three sisters” planting method which is pairing corn with beans/peas and squash/pumpkins. This magical combination works for several reasons, the first being that corn typically grows tall and provides something for beans and/or peas to climb, and squash stays low on the ground with large leaves and grippy tendrils to shade or squeeze out all those tiny little weeds that try to grow. Another reason that you may not know: beans naturally absorb nitrogen from the air and convert them into nitrates in the soil – one of corn and squash’s absolute favorite nutrients. Sounds like a match made in heaven, right? Well yeah, that’s why Indigenous Americans have been farming this way far longer than us white folks have even known their land was here.

For gardeners who enjoy growing lettuce (and other delicate greens) the lovely Calendula flower is truly a best friend. What backyard gardener hasn’t grown a delicious looking patch of lettuce heads just to discover one dewy morning that some adolescent slugs have worked their way into the layers of leaves and had their way with your prized greens? It’s devastating. Enter, Calendula with a stunningly characteristic bright orange (or yellow) superhero cape. Slugs are naturally attracted to Calendula, so give your delectable green friends a clementine-colored cape crusader to protect them. Bonus: the slugs won’t go after the flowers, so you’ll still be able to collect petals for herbalism, tinctures, teas, baking and craft projects.

If aphids tend to be more problematic for your lettuce than slugs (in drier climates), consider sowing chives near greens, or in between rows. Chives attract aphids as a barrier crop. For a brightly colored, pollinator friendly trap crop, consider nasturtiums planted within range of your lettuce, but not too close. Aphids will gravitate toward the nasturtiums rather than destroying your delicate greens.

Raise your hand if you love a good pickle. Go on, raise ‘em up! I LOVE pickling cucumbers (and radishes, and asparagus, and carrots, and garlic, and onions, and…well you get the idea). For those of us looking to keep our cucumber, squash and melon crops happy and healthy – There are several secret weapons! Cucumbers can benefit from nearby radishes acting as a pest deterrent – specifically for cucumber beetles and squash bugs. The pungent scent of marigolds has proven to be an affective pest control for many pesky crop destroyers that target melons, cucumber and squash, but work exceptionally well against thrips, white fly, squash bugs, aphids and cucumber beetles. Borage is frequently overlooked but is an exceptional plant to grow – a flowering herb that is completely edible on its own (flowers are a beautiful edible edition to baked goods and the leaves are dried and used in tea) it also brings ALL the bees to your garden and repels many common pests. Protect your cucumber harvest and increase your yield at the same time!

A couple more friendships to consider:

Beets love the cabbage family and planting them with onions and garlic will make them even tastier.

Potatoes love the cabbage family also, as well as beans, peas and eggplant, but they also need marigolds and horseradish for protection.

And if you love peppers, save some of your basil for your peppers for both improved flavor and protection from pests. Peppers also love tomatoes and alliums.

If this is all too much to remember, feel free to bookmark this page or save the graphic I created as a handy reminder.