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In my early years of gardening years, I came across the term Companion Planting too many times, to the point I thought it is an essential gardening practice. But when I was going through the chart, I got confused. So here is what you should know before to companion plant.

What is companion planting?

According to the dictionary, companion planting is the close planting of different plants, that enhance each other’s growth and protect each other from pests.

Companion planting is the practice planting of different crops in close proximity to each other in order to influence nutrient uptake, pest control, pollination, and other factors necessary to crop productivity“. According to Jeff Schalau, Associate Agent, Agriculture & Natural Resources
University of Arizona Cooperative Extension.

People, who believe in this practice, think that by planting certain plants next to each other has great benefits.

What you should know before you companion plant
Snapdragon under artichokes

Why to companion plant?

  • Tall plants provide shade to the shorter plants that do not withstand afternoon sun.
  • Tall plants with strong stalks, provide support for climbing crops.
  • Short plants with wide leaves provide shade for the soil and suppress weeds.
  • Some plants, such as legumes, provide extra nutrients by fixing Nitrogen in the soil.
  • Flowering plants attract beneficial insects ensuring pollination for the neighboring plants.
  • Use bait plants to attract and hold pests instead of attacking the neighboring crop.
  • Scented plants act like pest deterrents keeping cropping plants safe and healthy.
  • Some plants emit chemical compounds that inhibit other plants’ growth.

Does companion planting work?

Unfortunately, many of the companion planting benefits mentioned above are not supported by scientific evidence. There is no evidence that planting alliums next to beans, will prevent the latter from growing. In fact, many gardeners reported doing just that with no problem. They had a great harvest from both.

Click here to hear what other gardeners are saying.

The issue is not in the practice itself but in its name. The expression “companion planting” seems to be too wide for a detailed scientific study. In his brief post, Mr. Jeff (Associate Agent from Arizona University) mentions his colleague, Mrs. Linda Chalker-Scott’s thoughts on the matter. In her words, ” The phrase “companion plant” is too vague to be useful to plant scientists and professionals; the terms “intercropping” and “plant associations” are more definable and credible…”

Then she goes on by saying that ” Pseudoscientific, mythological and occult applications of “companion plantings” are not scientific …; and traditional “companion plant” charts have entertainment, not scientific, value.

In my nine years of gardening, I found that using the companion plant chart as a guide and applying, as a rule, was rather stressful. Most of the pairs mentioned would not work in my growing zone. It is more useful to look at companion planting from the angle of intercropping.

What you should know before you companion plan

What is intercropping?

According to the Oxford Dictionary of language, intercropping is to grow (a crop) among plants of a different kind, usually in the space between rows.

At first glance, intercropping is no different from companion planting. However, there is a slight interesting difference. Intercropping does not limit the crops you can grow together. It more about using the space wisely and get more harvest from it.

We can consider that intercropping is inclusive of companion planting with the focus on biodiversity.

Intercropping vs companion planting

Contrary to companion planting where plants are believed to influence each others’ growth, intercropping is about using planting space in a smart way. Not sure if planting basil in between tomato plants will make them taste better, but certainly the scent repels some insects. And making use of that space is better than leaving it bare for useless weeds to grow.

I would not plant potatoes next to carrots, not because they don’t withstand each other, but because they both grow underground. Obviously, potatoes will take over and there will be no chance for carrots to thrive.

In some sort, companion planting is not excluded from intercropping. It is the claims that have no scientific ground. According to Mrs. Linda Chalker-Scotts, Extension Agent with Washington State University, “traditional “companion plant” charts have entertainment, not scientific, value.

growing garlic
Potato bed outlined with garlic

What is the downside of companion planting?

The main down side of companion planting is the belief that a gardener has to stick to the chart for it to work. It is rather stressful for a new gardener to figure out which plant goes with which.

Another negative point is that in warm climates where there are two growing seasons, many of the pairings in the chart are not possible. Take a look at the bean companion plant chart:

FriendsEnemiesNote
Beans
Beets, carrots, chard, cabbage, corn, cucumbers, peas, radishesGarlic, onionsNasturtiums and rosemary deter bean beetles

In my growing zone 8b, the only crop I can companion plant with the bean is cucumbers, the rest don’t share the same growing season. Then, I would rather skip pairing cucumbers with beans for their vigorous vines will create a haven for stink bugs and aphids. Even if I use bush beans, instead, aphids will still be a big problem.

Then it recommends Nasturtiums and rosemary to deter bean beetle. Again nasturtium is a cool-season plant while beans grow in the summer. As for rosemary, it is an ornamental, perennial plant that grows to be a substantial bush. I would rather add it to the landscape than put it in the veggie garden.

Most common companion plants

what you should know before you companion plant

Why some plants are seen as enemies to others?

The truth is there is no war between plants, but there are bad combinations. It all goes back to smart planting. There are many obvious reasons why some plants should not grow next to each other.

  • Shared pest: Tomatoes and corn attract the same destructive pest, that is the hornworm. Planting them close to one another will trigger an infestation of this pest.
  • Shared disease: Tomatoes, peppers, and potatoes share the same fungal disease. It is a good idea to plant them away from each other to avoid cross-contamination.
  • Imbalanced feeding: planting two plants that feed on the same main nutrient may compete against each other. Better plant complementary plants for equal
  • Overwatering and underwatering: Grouping plants according to their water requirements is important. It will not only save the drought-tolerant ones but will also help conserve water.
  • Sun and shade: Planting two sun-loving plants together may look alright. The problem shows up when one grows tall while the other stays short. The latter will become shaded and won’t do so well.

The idea is to create a self-supporting environment for the plants.

How to intercrop in a home garden to increase yield?

Here are some ways I use intercropping in my 224 sq ft growing space.

  • Use garlic, onions, and leek in to outline the raised bed instead of using a physical grid.
  • Plant basil between to peppers, tomatoes, and eggplants. No need to dedicate a special bed for your basil, it grows well even when slightly shaded by these plants.
  • Plant sprawling winter squash in between beans, or peppers, and eggplants. The vine will shade the ground, serving as mulch without smothering the standing plants.
  • In winter the raspberry dies back, and the bed looks bare after pruning the old branches. In the space scatter parsley and cilantro seeds.
growing parsley and cilantro

Conclusion

If you have been using companion planting and it has been working for you, so be it. If you are just starting a garden, I would advise you to not complicate things and try the to follow chart to the letter.

It is best to experiment and not limit yourself. Gardening is an adventure that each one of us lives differently. Enjoying the successes as well as failures is the key to happy gardening. Keep it as simple as possible and follow your instinct.

References and interesting reads

Backyard gardener: Is companion planting scientific

SFGate: What Vegetables Should Not be Planted together

Farmers Almanac: Companion Planting

Sweet potato companion plants

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