by Sydney J. Tanner
Chemical, physical, and spatial interaction between plants has been scrupulously studied both in the garden and in the kitchen for centuries. Companion planting in the garden is a way to use that knowledge and nurture symbiotic relationships between plants. The theory of beneficial planting has deep roots in folklore and millennia of garden records and stories. Most of it’s scientific roots display basic common sense and have been used for the most part, in small-scale and home gardens.
Ever since Rachel Carson’s book Silent Spring was published in 1962, the environment and natural gardening have been pushed into the public view. In the 1970s, there was a movement toward “back to the land” and organic gardening and farming. Books, magazines, and pamphlets were published detailing the “brand new concepts” of composting and mulching. Articles in The Mother Earth News discussed in detail the “how tos” of organic gardening and companion planting. Many master gardening gurus like Ruth Stout, Mansanobu Fukuoka, John Battendieri, Robert Rodale, and Louise Riotte made the circuit with lectures and workshops. I listened to them.
Companion planting was (and still is) considered one of the mysterious secrets of organic gardening. Books, magazine articles, and pamphlets are still being published with information about it. The basic premise is, to plant one type of plant next to a different species that will give both plants benefits. In some places it is still a hot topic and passionately debated.
The idea was certainly not brand new. It is ancient, and just re-discovered in the 1970s with a push for the gardening and farming population to join in. Throughout history, companion planting has been practiced by many cultures all over the world, not just on our continent. Oriental gardeners used the knowledge for crop productivity. The Romans and Greeks used it for pest control. The Native American “Three Sisters” (corn, beans, and squash) are frequently planted together as a sacred rite.
In her books Roses Love Garlic and Carrots Love Tomatoes, Louise Riotte details hundreds of ideas of what to plant next to what in the garden and orchard. When I was in college, I had to study Riotte’s work. I found the ideas fascinating, but put her into the “organic kook” category with other “new age” thinkers and dismissed the work because it wasn’t scientific enough for me. Over thirty plus years (and more than that gardens) later, I picked up, and studied her work again as a Master Gardener. Now I’m impressed at her insight and knowledge.
The scientific studies of companion plantings have just given chemical analysis, reaction names, and the “technical why” to the way planting systems work. The systems would have worked without the science. They’ve worked for over a thousand years and they’ll continue without the science. However, it is nice to know there’s a reason behind the adages.
There is an agricultural formula called the land equivalent ratio (LER) that scientists use to measure the success of intercropped plantings. This is the ratio of harvest from an area of single cropped land to the area of companion planted land. Research has shown that the same yield can be produced from a smaller area that is intercropped. Companion planting works. Advocates for container, raised bed, strawbale, and square foot gardening know this concept pretty well, and practice it. If it works for small square foot gardens, why wouldn’t it work for large scale farming? The answer is, that it does!
Many gardeners companion plant and just call it by another name. Nurse cropping, intercropping, or interplanting is one method of companion planting that some gardeners follow. It is the practice of planting a tall, densely canopied crop, with a shorter, more delicate crop underneath. An example would be growing corn and beans together. The corn stalk provides the trellis for the beans, or planting oats and alfalfa together. The taller oats, protect the alfalfa as it gets established. Sometimes, the method is called “mixed planting” or polyculture. At least two vegetable or herbs are planted at the same time, in the same place.
Not only does polyculture increase productivity, it encourages biodiversity, creating a stronger agricultural atmosphere. Biodiversity brings harmony to the garden. In today’s “Going Green” society, polyculture or companion planting is again “re-discovered” as part of the “new” reconciliation ecology movement. That’s another big title for knowing and living close to the land.
Some helper plants, like marigolds, need more than one season in a place to be effective on nematodes. This is called accumulative protection. In planting “the Three Sisters” together, the gardener creates a sustainable atmosphere and soil, with the three plants nurturing each other, the soil, suppressing the weeds, and evading pests.
A little time needs to be spent deciding on pairing fast vs. slow growing, long vs. short season, and the nutritional needs involved with the paired plants. With a little planning, gardeners can choose inventive succession pairings in their seasonal plantings to help with specific garden problems or pests.
Pest control is a major benefit from companion planting. Certain companion plants can be hosts for helpful insects and arthropods. Other plants can be planted to lure pests to their leaves and branches. This practice is called trap-cropping. These decoy plant attractants act as a congregating place for pests or a pathogen. An example of this would be planting nasturtiums to attract aphids and flea beetles, to keep them away from your other plants. There are even companion plants to help rid your garden of Japanese beetles!
To get started, there are plentiful resources from the old standby books and articles, to Internet sites devoted to nothing but companion planting. UW Extension Services has published several articles regarding the virtues of companion planting, both on general terms and specific plants. These are available at your local extension office or online. Each gardener that discovers companion planting and uses the knowledge to better his/her garden, makes the world a little better.
Do NOT plant alliums near beans, peas, parsley, sage,
DO plant alliums near nightshades, brassicas (rabbit deterrent), carrots, chamomile
Do NOT plant asparagus near alliums, potatoes, garlic, iris, gladiolas
DO plant asparagus parsley, basil, tomatoes (bug trap for beetles), lettuce,
Do NOT plant beets near mustards, pole beans,
DO plant beets near curcurbits (especially kohlrabi), lettuces, alliums, catnip, garlic, mint
Do NOT plant brassicas (turnips, baggies, cauliflower, bok choy, broccoli, cabbage, collard, kohlrabi, brussels sprouts, …) near nightshades, strawberries, legumes, some other brassicas,
DO plant brassicas near mustards, celery (deters cabbage butterfly), chamomile, mints, sage, rosemary, thyme (especially with cabbage), tansy, nasturtiums,
Do NOT plant carrots near apple trees, parsnips, radishes, anise, dill,
DO plant carrots near tomatoes, alliums, herbs (like rosemary), beans, peas,
Do NOT plant celery near corn, asters, parsnips, potatoes,
DO plant celery near alliums, nightshades (except potatoes), brassicas, beans, peas, curcurbits, snapdragons,
Do NOT plant corn near nightshades (except potatoes), celery,
DO plant corn near curcurbits (especially cucumbers which raccoons hate), legumes, potatoes, morning glory, sunflowers, peas,
Do NOT plant curcurbits near nightshades (especially potato), sage,
DO plant curcurbits near corn and beans (3 sisters), tansy, catnip, radishes (which is a bug trap crop), buckwheat, chamomile,
Do NOT plant horseradish near carrot, curcurbits, raspberries, sunflowers, tomatoes,
DO plant horseradish near potatoes,
Do NOT plant beans near alliums, sunflowers,
DO plant beans near savory, corn, celery, curcurbits, eggplant (mutual bug repellents), spinach,
Do NOT plant lettuces near broccoli,
DO plant lettuces near garlic, alliums, asparagus, carrots, sunflowers, strawberries,
Do NOT plant nightshades (tomato, eggplant, potato, peppers) near peas, other nightshades, brassicas, beans, corn, fennel dill, curcurbits (cucumber, squash, melons)
DO plant nightshades near carrots, alliums, mint, basil, oregano, geranium, petunia, marjoram, horseradish,
Do NOT plant peas near alliums, garlic,
DO plant peas near spinach, beans, carrots, turnips,