It was my father in-law who first introduced me to the concept of companion planting, as we discussed gardening, and he sagely shared the secret of planting marigolds with tomatoes in order to repel nematodes. I remember wondering what other plants could be grown among my crops to aid in the health of the garden, and then I wondered why more people don’t use this age-old method of pest protection?
If you’re interested in organic gardening, and gardening without the use of pesticides or herbicides, it’s a pretty safe bet that you’ve entertained the notion of companion planting. Chances are you’ve Googled companion planting and discovered the 1,410,000 results that come up, clicked through the first few links, and quickly became overwhelmed by the vast number of recommendations for pairing combinations of plants–I know I certainly did! There seems to be no rhyme or reason to the suggestions, which are sometimes confusing, unscientific, and even contradictory.
About 10 years ago, I was lucky enough to stumble upon Sally Jean Cunningham’s book: “Great Garden Companions“, in which she lays out her companion-planting system–a system that takes the confusion out of companion planting and makes it easy to employ this method to aid in your pursuit of a chemical-free garden. Even on a larger scale, as in our market gardens, companion planting can be utilized to reduce the need for pesticides, and to improve the efficiency of the garden.
Sally Jean is a Master Gardener with the Cornell Cooperative Extension, and she’s done the hard work of sorting through hundreds of companion planting recommendations, looking for those recommended by several sources and backed by scientific research. And, as a Master Gardener myself, I prefer to use information supported by the cooperative extension and grounded in science, so Sally Jean’s book was a godsend.
Some may call the companion-planting method merely an “old wives tale”, but just because something is folklore doesn’t mean it’s fiction. Afterall, companion planting is one of the oldest of gardening traditions–even the ancient Roman historians wrote about companion planting–and practically everyone has heard of the “three sisters”, a Native American method of planting corn, beans, and squash together.
Note: This is not an affiliate link, though I do highly recommend “Great Garden Companions” to anyone interested in this method of growing and raising crops.
What is companion planting?
Simply put, companion planting is combination of gardening fact and folk-lore that advocates growing certain plants together for their mutual benefit–a symbiotic relationship of sorts.
Humanity’s modern gardening methods disregard and destroy the natural systems in effect on Earth because we often feel the need to interfere with the links of the living chain, which causes the system to begin to collapse. However if we set up our gardens to take advantage of the natural processes that make nature so successful, we can create a self-sustaining system that is a benefit not only to ourselves, but to the ecosystem that we are a part of.
What are the benefits of companion planting?
Creates biodiversity: Planting flowers and herbs among your vegetables in the garden creates biodiversity, which means having many different plants and animals in the area, and supports the natural systems at work, creating a healthier, stronger ecosystem. When your ecosystem is strong, the plants and animals therein are stronger and healthier too. And if your vegetable plants are strong and healthy, they can ward of pests and diseases more easily, which means you’ll have a better harvest than you might otherwise reap.
Helps prevent pest problems: Mixing plants together makes it more difficult for pests to find those they like to eat. Inter-planting flowers and herbs among your crops confuses the insects in some cases. In other instances, your companion plants may camouflage your vegetables. Some odoriferous plants repel pests, and still others attract natural predators such as birds and beneficial insects.
A helping hand: Some companion pairings help each other grow, such as corn that’s planted beside lettuce, shading the lower growing crop from the hot summer sun. And even sunflowers that are planted between your cucumbers, creating a natural trellis for your vining crops.
Use nutrients efficiently: Make the most of what your garden’s soil has to offer by pairing plants according to their nutrient needs. Some crops need well fertilized, rich soil, while others do just as well in average, or even fairly poor soil. A good example is pairing potatoes with beans, potatoes are heavy nitrogen feeders, and since beans effectively fix nitrogen into the soil this is a great companion pairing. In other instances, following a group of heavy feeders such as tomatoes or cucumbers with a planting of light feeders such as beets or carrots, can help you utilize your soil most efficiently.
Reduces need for pesticides: Companion planting allows you to grow vegetables, flowers, and herbs in a chemical free, environmentally friendly way. Growing strong, healthy plants that are less susceptible to pests and disease, and growing them with beneficial friends and allies to help ward off pests, reduces, and potentially eliminates, the need for pesticides in the garden.
Companion planting the easy way
I’ve adopted Sally Jean’s gardening method, which takes the confusion out of companion planting, and I’ve had great success with it. By sorting your plants into basic groups companion planting suddenly becomes a much simpler endeavor.
Step 1: Sort your crops into plant families
There are 4 ways to group your vegetable crops into families, by botanical family, feeding needs, performance benefits, and pairings that benefits each other by deterring or warding off harmful pests. Depending on your circumstances you may choose to employ just one of these groupings, or all of them.
Genetically related plants can be grouped together, since they typically have similar needs for light, moisture, and fertility. Plants of the same family are often plagued by the same pest and disease issues, so grouping them together can make treating these problems much easier. For example, group brassicas together in one family, tomatoes and peppers together in another. Organizing your plants this way also helps you to choose the appropriate friends for each crop family.
Group plants according to their nutrient needs, as some are heavy feeders, while others are moderate to light feeders. Corn, cucumbers, peppers, tomatoes and squash are all crops who need a rich, well fertilized soil to produce well, while beets, carrots, onions, and turnips all do well in average or even poor soil conditions. Grouping your crops into feeding families can help you to make the most of your soil fertility, and this can be a good strategy for those with smaller gardens, or if you have poor soil that you’re working to improve.
Some plants can help another by simply being in close proximity, such as lettuces planted in the shade of pole bean tee-pees. This kind of grouping can help you make the best of limited garden space, with the added benefit that insects may become confused by the close placement of the two unrelated crops, and they may not be able to find their target crop.
In this grouping, one family member may help repel pests that attack another family member. Or one crop might lure pests away from another crop. Research studies have indicated that bush beans planted in alternating rows with potatoes can significantly reduce the numbers of Colorado potato beetles afflicting your potato crop. Radishes, too, are a great trap crop used to lure flea beetles away from your greens–just pull up the infested radishes and destroy them to get rid of the flea beetles.
Step 2: Choose your friends carefully
Once you’ve created your “plant family” it’s time to add some “friends and allies”.
Plant friends attract beneficial insects to the garden–beneficials are those who either prey upon garden pests, or those who pollinate, thus increasing the yield of your garden. But in order to attract these “good bugs” we need to offer them food and shelter, because when beneficials aren’t eating pests, they eat pollen–another protein source, and they like a place to hide when threatened or resting.
Plant allies are protector plants, or trap crops, which deter, or lure pests away from your vegetable crops. Typically these include common annuals (ie-marigolds, etc.) and culinary herbs, and even some perennials in adjacent beds can offer a benefit to your vegetable garden.
2 Rules for choosing ally-attracting plant-friends
- Provide a season-long bloom: beneficial insects need to be able to eat from the time they emerge in the early spring, through to the fall, when cold forces plants into dormancy and insects either die off or return to hibernation.
- Include aster and carrot-family plants: there are many aster-relations to choose from–from sunflowers to coneflowers, daisies, chamomile, cosmos, zinnias, and many more–all of them offer nectar and pollen to beneficial insects. The carrot-family, however, includes many odoriferous herbs–such as caraway, dill, fennel, parsley, and even Queen-Anne’s Lace–which serve as our protector plants.
Step 3: Survey your plant neighborhoods
Once you’ve grouped your crop families it’s fairly easy to pair them with beneficial allies to create neighborhoods that suit your specific preferences and gardening principles. Decide which type of mulch best suits each neighborhood, determine optimal crop rotation, and make notes for future reference as you experiment and learn. You can check out my own neighborhoods below to see what some possible groupings might look like.
Pairing cabbage-family crops with other cold-loving crops makes sense if you’re interested in season-extension.
I absolutely avoid using straw as a mulch because slugs and snails love to hide in it during the day, then lunch my tender brassicas during the cool nighttime.
The brassica neighborhood has a 2-3 year rotation period in my gardens, so they won’t be in the same plot again for at least 2 years, and we always remove spent plants at the end of the season because they can harbor pests and diseases over the winter.
When my garden was smaller, serving just our own family, I would plant my onions, and then scatter-sow carrots between them, using the thinnings in salads.
Now that we have a much larger market garden, I plant in wide beds, alternating carrots, onions, and beets.
These crops are generally not prone to disease, but do we employ a 2 year rotation period for carrots, since they can be affected by root maggots, while greens can be planted in the same bed repeatedly without a problem.
Beans with potatoes
I always pair potatoes with beans–firstly because the beans act as a trap crop for my more valuable winter-storage crop of potatoes. And secondly because legumes like beans fix nitrogen into the soil, and since potatoes are heavy nitrogen feeders this is a good plant-relationship to foster in the garden.
Because potatoes are susceptible to a number of diseases we give them a minimum of 3 years in our crop rotations.
Generally, these heat-loving, nutrient-demanding crops will go in the garden around the same time.
Crops like cucumbers, squashes, and pumpkins need plenty of space to spread out, rich, fertile soil, and hot, humid weather to perform well.
Another companion planting strategy is to plant cucumber among your cabbage-family crops early in the season; you will have harvested the brassicas by the time your cucumber-crops need more space.
3 year rotation to avoid reintroducing pests, like the Cucumber beetle, which overwinter in the soil, mulch, and nearby logs or the debris of the forest floor.
Keeping a permanent bed in the garden not only gives you a place to plant perennials like rhubarb and asparagus, but also offers a dependable habitat to beneficial insects.
Providing shelter and water entices the insects to remain close by, which will increase their foraging in your garden and further reduce the numbers of pests preying upon your crops.
Companion planting doesn’t have to be complicated or confusing. Using this method of grouping plants based on one of the four categories, and pairing them with friends and allies that suit each plant family takes the guess work out of it all. And by arranging your garden into “neighborhoods” you’ve created an easy rotational system.
I’ve printed my own neighborhoods onto index cards, with my notes and reminders, so that they are easy to refer to. I can carry them with me in my back pocket when I go out to the gardens to plant, and I double check them constantly to make sure I’m putting the right seedlings together, and laying the correct form of mulch.
Now that you know how–go ahead and create your own garden neighborhoods and try companion planting for yourself!