While June 5 is always the optimal — safest — time to plant vegetables (and almost everything else), it’s a good idea to spend some of the March bluster planning where and how to work with some of your favourites. Over the years, this column has expanded in scope to include companions of all stripes – vegetables, fruits, herbs, flowers, and even some “weeds” – which you can use or ignore as you see fit. That said, here is your annual list. Enjoy!
Remember that some companion plants can serve as “trap crops” that will keep foliage/bulb eaters and their larvae away from the main crop. The following table offers choices for the protection and beauty of your personal garden landscape. I have referred to plants as “friends” – which grow well together, or as “enemies” – which prevent proper beneficial interaction. You will notice that some vegetables are quite tolerant while a few others are averse to certain bed partners.
asparagus: Friends — tomatoes, parsley, basil;
Green and/or wax beresponds: Friends — corn, potatoes, carrots, cucumbers, cauliflower, cabbage, petunias, oregano, mustard, savory, rosemary; Enemies: onions, garlic, gladioli.
Green beans: Friends — corn, squash, oregano, mustard, savory; Enemies: onions, beets, sunflowers, cabbage.
beets: Friends: onions and cabbage; enemies: polar beans.
Coles: (broccoli, brussels sprouts, cabbage, cauliflower, kale, kohlrabi) : Friends: mint, dill (and most herbs), potato, celery, beetroot, onion (cabbage particularly likes Sage) ; Enemies: strawberries, tomatoes, green beans.
Chinese cabbage (different from American cabbage crops) – Friend of peas, but enemy of green beans.
Carrots: Friends — peas, lettuce, chives, tomatoes, onions, rosemary, sage; Enemy – dill.
But: Friends — potatoes, cucumbers, peas, beans, squash.
Cucumbers: Friends — beans, corn, peas, radishes, sunflowers; Enemies — aromatic herbs*, potatoes.
Aubergine: Friends – beans, basil.
Fennel: Although a delicious bulb with licorice-flavored fronds (which flavor baked fish), fennel is not a friend of almost anything in the garden. Give it a private space with sunlight and rich soil away from the vegetable garden;
Leeks: Friends — celery, carrots and onions.
Salad: Friends — carrots, radishes, strawberries, cucumbers.
Melons: Friends — beans, corn, peas, radishes, thyme, sunflowers; Enemies – potatoes, most aromatic herbs.
Onions: Friends — beets, strawberries, tomatoes, lettuce, chamomile, savory; Enemies: peas, beans.
Parsley: Friends – (and beneficial to), tomatoes, asparagus, roses. (Parsley is both food for swallowtail butterfly larvae (a green/black striped caterpillar). I once suggested planting “sacrificial” parsley as a beneficial ornamental in the rose garden and planting kitchen parsley in the vegetable garden.
Peas: Friends — most vegetables and herbs; Enemies – onions, garlic, gladioli, potatoes.
peppers (Sweet bells/Hot): Friends – most vegetables and herbs; Enemies: onions, garlic, gladioli, potatoes.
Potatoes: Friends – beans, corn, cabbage, horseradish, eggplant, gladiolus; Enemies – pumpkins, squash, cucumbers, sunflowers, tomatoes, raspberries.
pumpkinssquash: (see squash).
Radishes: Friends – peas, nasturtiums, lettuce, chervil, cucumbers (planting lots of radishes with your peas and cukes will trap many harmful pests).
Roses: Friends — Borage, chives, garlic, lavender, leeks, mint, parsley, rosemary, rue, sage, santolina, thyme, wormwood (mugwort), tansy.
Rutabaga, turnips: Friends of peas, but NOT each other: remember that these related crops (including radishes) will interbreed, also with Chinese cabbage and oriental mustard, so don’t plant together if you want true-to-life produce the species.
Squash (summer and winter): Friends – nasturtiums, corn. (Only plant one variety of squash per species to avoid crossbreeding).
Spinach and chard: Strawberry friends – plant in the strawberry bed for mutual benefit.
Tomatoes: Friends — chives, borage, thyme, onions, parsley, asparagus, marigolds, carrots, nasturtiums; Enemies: Cabbage, potatoes, fennel.
Watercress/mustards: Compatible with most vegetables and aromatic herbs.
*Note: multiple references to “herbs” may include nasturtiums, calendula and marigolds as well as the following: sage, tarragon, chives, sweet marjoram, summer savory, dill, rosemary, basil, mints (including Betony) , oregano, thyme, sorrel, all culinary herbs. Perennial culinary sage can provide a lovely focal point among your cabbage plants.
Non-culinary herbs like rue, sagebrush (wormwood, wormwood, etc.), are NOT good in the vegetable garden, but really valuable in other areas of the landscape. A herbal tea made from rue or wormwood sprayed on plants infested with aphids, etc., to deter and/or kill them.
Umbelliferae (think umbrellas) make excellent trap crop plants to attract the “good guys”: caraway, dill and Sweet Annie attract hoverflies which feed on many species of aphids. The tiny beneficial wasps that parasitize the eggs of caterpillars, spanworms and other destructive worms also enjoy a variety of umbelliferae including yarrow, tansy, valerian and angelica. The white cosmos attracts the precious lacewing, which feeds on aphids, thrips and scale insects. These and other valuable insects are garden assets, giving you a good reason never to spray. Companion gardens are designed to be worry-free.
Special Warnings: Pay special attention to enemies and never plant them with their enemies listed. Some reactions are destructive to unfriendly plants. Plant catnip around borders to control flea beetles; Yarrow is beneficial in interplanting with all vegetables and compatible with most aromatic herbs.
Tansy deserves special mention here: Although considered a noxious plant – dangerous to grazing livestock – small clumps here and there in the landscape are beneficial as a trap crop, especially with roses, peonies, raspberries, grapes and fruit trees. The ones I keep as companions to my many peonies are always literally covered in tiny pollinators without ever a “bad guy” on any of the surrounding flowering plants.
Companion planting, interplanting, and trap crop gardening are both practical and beautiful, so use the previous information to plan and plant your vegetable/herb/ornamental gardens for healthy and successful harvests.
Valle Novak writes the Country Chef and Weekend Gardener columns for the Daily Bee. She can be reached at [email protected] or by phone at 208-265-4688 for questions between 8 a.m. and 6:30 p.m. at 208-265-4688.