I love the visual appeal of a tidy, organized vegetable garden. I have a helpless crush on the promise of using clever hand-made plant markers to identify well-groomed rows of tomatoes and groups of herbs, all growing neatly in their appointed spaces.
Despite my irrational fondness for mini-monocultures and neat little rows, I’ve come to accept that my garden will probably never be well-groomed or organized enough for a plant marker, and that’s OK. Indeed, putting a variety of plants together in one bed is often a much better plan than grouping each type of plant together in one place. Plants can help each other out in a surprising number of ways when they’re allowed to intermingle.
Companion planting has been practiced for centuries by farmers and growers all around the world, but it’s the home gardener, often working with a smaller amount of space, who can benefit the most from learning which plants make good bedfellows. Since now is a great time to start planting so many of our cool-season veggies and herbs, this is the perfect time to consider a wilder approach with your next garden plans. This planting season, why not see what happens when you mix things up a bit, and use small spaces to your advantage?
We know that large groups of the same type of plant are much easier to spot (or smell) from a distance, so one of the first benefits of growing a mixed variety of plants together is that hungry critters will have a more difficult time finding their favorite snacks. And there are a number of other less-obvious interactions happening at the same time. The smell of one plant might help mask the smell of another; a smaller plant may stay protected beneath a bigger plant’s canopy; and another plant could help repel a pest or pathogen.
Sunflowers, for example, are tall enough to provide excellent afternoon shade for tomatoes in the summer. The snap beans and peas that we plant by seed in September or as transplants in October are known to boost the growth of nearby plants by increasing nitrogen levels in the soil. When grown within the vegetable beds rather than sequestered to the herb garden, certain herbs can help keep pests and pathogens at bay, and can often lend a subtle flavor to vegetables grown nearby.
It’s interesting to note that what’s good together on the plate will often grow well together in the same soil. Such is the case with tomatoes and basil. Basil is said to impart a delicate flavor to tomatoes, and gardeners have noted that both plants seem to just do better when the other is growing nearby. Like a lot of the aromatic herbs, basil plants produce substances that have some antimicrobial and antifungal properties while also deterring some pests with their strong scent. Tomatoes, on the other hand (and some other members of the nightshade family), produce substances that help deter harmful nematodes in the soil.
Perhaps that’s why asparagus—which many of us can begin planting around the beginning of October—gets along so well with both tomato and basil plants. Although it takes a while for this crop to pay off—you should wait at least one year before your first harvest—once you get asparagus going you’ll have fresh spears to harvest every spring (and sometimes summer) for 12 to 15 years. Parsley is a great cool-season herb to seed around your asparagus starts in fall. These two plants will happily keep each other company until you can add some basil and tomatoes to the bed next spring.
Another famous pairing is strawberries with spinach. If you’re one of the many of us who just planted strawberries in August, try starting some spinach from seed in the same bed. Both plants have similar soil and food preferences, but their roots occupy different soil levels, so they’re not in direct competition for nutrients. In addition, the saponin produced by the spinach helps to repel some of the bacteria and fungi that can keep strawberries from thriving.
Now is a great time to plant any of the brassicas (also called cole crops: cabbage, cauliflower, Brussels sprouts, broccoli, collard greens, kohlrabi, turnips, rutabaga, and kale), but you’ll want to try to keep them away from tomatoes, strawberries, radish, or pole beans. Most plants in the cabbage family prefer growing near celery, dill, onions, leeks, or potatoes.
Alliums (onions, leeks, garlic, shallots, chives) are all especially useful as companion plants in the garden. As you’re planting your fall and winter crops, disperse some allium bulbs throughout your lettuce, beets, and brassicas to help protect them from a number of nibbling critters and hungry pests.
Garlic is probably the best-known and most-used member of the allium family. This stinky bulb helps to protect all kinds of plants from pests, but keep in mind that companion planting doesn’t always mean that the benefits are mutual. Many of the plants that like to have alliums nearby don’t appreciate the dry soil conditions that are necessary for alliums to produce a tasty bulb. It’s sometimes the case that we grow two plants together for the benefit of one more than the other.
The only veggies that don’t like having an allium nearby are beans and peas. Plant these legumes along with some carrots, lettuce, or radishes instead. The deep taproots of radish and carrot mix well with the more fibrous roots of a lettuce, and the nitrogen bump from legumes growing in the same bed will make everyone happy.
In many ways, companion planting is all about fostering diversity in your garden beds. Having a good mixture of root types and differing speeds of growth within the bed will help reduce competition for nutrients. A variety of leaf types and a mixture of smells will help obscure your garden goodies from pests. A tiny ecosystem can exist in your own back yard! ✜
Amy Belk is a garden writer and photographer, a certified arborist, and a certified nursery professional who has been learning from her garden for 15 years (and counting). She and her husband homestead on a little piece of the desert in the heart of Tucson.
Baja Arizona includes a variety of elevations and hardiness zones. Most of us can plant the following veggies and herbs this September and October, but check with local resources for more detailed information about the best times to plant or sow seed in your area. If marked with an asterisk (*), it’s recommended that you don’t seed or sow until temperatures drop below 100.
Seeds to sow: anise*, beets, beans (snap), bok choy, borage*, Brussels sprouts, cabbage, calendula*, carrots, celery, chamomile*, chervil*, cilantro*, collard greens, cucumber, cumin*, dill*, endive, fennel, French sorrel*, kohlrabi, leek, lettuce, mustard greens, parsley*, peas, radish, salad burnet*, spinach, Swiss chard, turnips.
Plant/transplant starts of: asparagus*, beets*, bok choy*, broccoli*, Brussels sprouts*, cabbage, carrots*, cauliflower*, collard greens*, endive*, fava beans*, fennel*, garbanzo beans*, garlic, garlic chives, green onion*, kale*, kohlrabi*, lavender*, lettuce*, leeks*, marjoram*, mustard greens*, potatoes, onions, parsley*, parsnip*, radish*, rosemary*, rutabaga*, sage*, spinach*, sweet bay, Swiss chard*, thyme*, turnips*. For rhubarb and salsify, plant after September in cooler zones of Baja Arizona only. ✜