5. Companion Planting, Does it Really Work?

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5What is Companion Planting?

Companion planting is the idea of growing two or more species in close proximity so that some benefit, such as pest control, growth or increased yield, may be achieved. Companion planting is a form of polyculture, which is one of the principles of permaculture.

Photo of marigolds planted with tomatoes, as an example of companion planting.

Planting marigolds and basil with peppers and tomatoes will deter hornworms and are said to improve the flavor of the tomatoes.

Is Companion Planting Scientifically Proven?

The concept of companion planting is based on observation. Observations are noted when plantings of the same plant combinations give similar results, whether they were good results or bad. Here is the connection to being a science, by way of Webster’s Dictionary:

  1. Observation is an act of recognizing and noting a fact or occurrence.” Farmers and gardeners have been observing and noting the positives and negatives of plant combinations for centuries. The indigenous people of the Americas, prior to the arrival of Europeans, used companion planting. These peoples domesticated squash 8,000 to 10,000 years ago, then maize, then beans, forming the Three Sisters agricultural technique.
  2. Science is knowledge or a system of knowledge covering general truths or the operation of general laws especially as obtained and tested through the scientific method.” And the scientific method is?
  3. The definition of the Scientific Method is “principles and procedures for the systematic pursuit of knowledge involving the recognition and formulation of a problem, the collection of data through observation and experiment, and the formulation and testing of hypotheses. After repeating the integration of certain crops, farmers and gardeners found that there were notable changes in production, growth or insect damage. Also noted, are that certain crops do not do as well when grown in close proximity to certain other plants.

So it seems that companion planting is in fact a science, but not an exact science. I could find no official studies or data to confirm or deny the benefits of companion planting, mainly just observations.

What are the possible benefits?

  • Control your “problem” insects by planting flowering plants to attract beneficial insects. Plants such as dill and yarrow will attract ladybugs, hover flies, parasitic wasps, lacewings and Damsel bugs.
  • Confuse or repel some insects from their intended target by planting strongly scented plants nearby to mask their scent.
  • Provide shade or protect a delicate plant from wind by locating a taller plant in front of it.
  • Certain plants can provide nutrients to the soil for other plants to take up. Legumes (peas, beans, clover and more) can “fix” or convert atmospheric nitrogen into a form that becomes usable to plants. Comfrey will provide extra nutrients like potassium, phosphorous and calcium by drawing the nutrients up through their root system. Borage has a long taproot that will add potassium, calcium and other nutrients into the soil.
  • Also try trap or decoy plants. Similar plants are grown to distract pests from your main crops and are therefore considered to be sacrificial plants. Planting collards will help draw the cabbage moth away from your cabbage and planting dill and lovage will draw the horn worms away from your tomatoes. Check the trap plants often and spray with an organic pesticide to kill the pests.
  • Increase productivity by planting deep rooted plants with shallow rooted ones, so there is less competition.
  • Likewise, plant heavy drinkers with those that like to be in drier soil provide mutual benefits.
  • Companion planting can increase vigor and yield of their neighbors.

Are there Bad Companions?

Some plants do not make good companions. Planting dill with carrots will stunt the growth of the carrots. Don’t plant all Brassicas (cabbage, cauliflower, broccoli, etc) together. The same insects attack them all. Mature dill will stunt tomato growth, although young dill plants are good for them. Pick the dill before it matures? Garlic and onions will inhibit the growth of peas and beans.

Overview of Using Companion Planting.

Keep in mind that there are many other factors that will affect your vegetable garden’s results. Start with good soil, compost, healthy plants and seeds from a reliable source. Take the time to maintain and observe your garden for problems before they get out of hand. The soil’s pH, weather conditions, soil fertility, soil quality and available sunlight will probably affect it more than companion planting will. But hey, don’t shrug off thousands of years of observation and practice. Even just planting flowers like marigolds, alyssum and borage and herbs like basil, thyme, oregano and rosemary may help. At least you may attract bees for pollination, have fresh herbs for cooking and make your garden more beautiful!

You can find many different Companion Planting charts all over the internet, with some better than others. This one is my favorite! Just click the chart to see an enlarged and printable copy.




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