The Covid-10 pandemic has brought home, as nothing else could have, the vital importance of friends in our lives. Friends one sees every week, friends one sees now and then, even friends one meets up with once in a blue moon. They all form the human landscape in which we grow and thrive, or wilt, as the case may be.
Plants also have companions with whom they do well or poorly, depending on various factors. If you put plants that “like” each other – meaning do well together – near each other, the results can be far happier than if they grow alongside plants that leave them cold or actively disrupt their lives.

“Like” is shorthand for saying some plants derive protection from their pest and disease enemies, thanks to other plants which ward off bad bugs and/or affect the soil in a beneficial way.
Have you all but given up planting squash, melon or cucumbers because of squash borers and cucumber beetles? Try planting radishes and nasturtiums nearby. Nasturtiums, incidentally, have a delicate, primrose-like fragrance disliked, apparently, by borers and cucumber beetles. Their leaves and flowers also taste delicious in salads, adding a cress-like flavor and bright color – yellow, orange and red.

Conversely, some plants do poorly when planted alongside some others. Tomatoes and bush beans languish near fennel. Tomatoes also dislike kohlrabi. Fussy tomatoes!
Other dislikes: Pole beans and sunflowers (root and light interference), potatoes and sunflowers (both will do badly), pole beans and beets, pole beans and kohlrabi (what is it about kohlrabi?), red and black raspberries.
Herbs are star companions. Plant them in the borders of your vegetable patch. Their scent, which we love for the taste and smell it adds to cooking and potpourris, repels some destructive insects and possibly rabbits. Their small flowers attract pollinators, who will also pollinate your veggies.

Herbs such as rosemary, basil, anise, cilantro, dill and caraway, as well as crops like buckwheat, garlic chives, hyssop and broccoli raab also produce small blossoms prized by pollinators and predators of garden pests. Plant them next to your desirable crops and you’ll acquire valuable allies in the garden.
A good companion plant for borders is marigold. The flowers draw beneficial insects and, it is believed, may repel bad ones by means of chemical compounds in their leaves and roots.

Another angle on companions involves planting a species that’s even more delicious to pests than the crop you want to eat. This is called trap cropping. An example close to my heart: Raspberries and mulberries.
Most people, including this gardener, prefer raspberries to mulberries although, in a pinch, mulberries aren’t bad. But birds favor mulberries. In my garden the mulberries, which grow near the raspberry patch, ripen at about the same time, so the birds gorge themselves on the mulberries…up to a point. At least, it gives me a head start gorging myself on the raspberries.
Another example: Cucumber beetles love amaranth. Plant some of it before sowing seeds for squash, melon and cukes. When the beetles have flocked to the amaranth, cut it and wrap it, beetles and all, in a black plastic bag, then dispose of it.

Yet another angle on companion gardening: Take advantage of plants’ different sizes and nutrient needs — not only their height but how deep their roots reach. Plant roots grow to different depths and search out different nutrients in the soil. Put the right combination of plants together and they’ll help each other.
A well known example is the “three sisters” intercropping system, devised by the Northeastern native American tribes. They planted corn in a small circle, beans at the base of the corn and squash plants around the perimeter.
The beans climbed up the tall corn stalks for support and made the soil more fertile by nitrogen fixing, an ability that bacteria on the roots of legumes have for extracting nitrogen from the soil and making it more accessible to plants. The squash plants, meanwhile, suppressed weeds and conserved moisture in the soil due to their large, shade-making leaves and sprawling vines. The squash plants also made it more difficult for animals to reach the beans and corn.

Because I find it difficult to remember which plants prefer which, I rely on lists. The following plant companions can serve as great allies for you as you start planting your edible garden during the next few weeks.
For more information, read the excellent book “Carrots Love Tomatoes and Roses Love Garlic,” by Louise Riotte.
Plant: Asparagus near tomatoes (which repel asparagus beetles), parsley, basil; beans with/near carrots, potatoes, cucumbers, cauliflower, cabbage, summer savory and most other vegetables and herbs ; bush beans with celery, potatoes, cukes, corn, strawberries, summer savory; pole beans with corn, summer savory; beets with onions, kohlrabi.

Cabbage family (including cauliflower, kale, kohlrabi, broccoli, Brussels sprouts) near mint, potatoes, celery, dill, chamomile, tomatoes, rosemary, sage (to repel cabbage maggot), beets, onions and beans; carrots near peas, leaf lettuce, chives, onions, leek, rosemary, sage, tomatoes; chives with carrots; corn with potatoes, peas, beans, cucumbers, pumpkin, squash; cucumbers with dill, beans, bush beans, corn, peas, radishes, sunflowers.
Eggplant with beans; ; leeks with celery, celeriac, beans, carrots, onions; lettuce with chervil, carrots, radishes, strawberries, onions; onions (including garlic) with beans, beets, strawberries, tomato, lettuce, summer savory; potatoes with beans, corn, cabbage, eggplant (as a lure for Colorado potato beetle); early potatoes near beans, corn and/or horseradish (at corners of patch); pumpkin with corn; radishes with a row of lettuce on each side (makes radishes tender and more healthy), peas, nasturtium, cukes.

Spinach with strawberries; squash with nasturtium, corn; strawberries with bush beans, spinach, borage, lettuce, thyme (as a border); sunflower with cucumbers; tomatoes near parsley, chives, onion, asparagus, marigold, nasturtium, carrot; turnips near peas.
If a plant goes well with a whole string of other plants, such as cabbage, you don’t need to plant all of them. One or two may suffice. In the list, which probably gives only a sampling of the potential plant companions, “with” is interchangeable with “near.”
In the meantime, happy gardening!

Editor’s Note: Laetitia Sands is a master gardener in Dorchester County.