In my early gardening years, I came across the term Companion Planting too many times, to the point I thought it was an essential gardening practice. But when I was going through the chart, I got confused. So here is the truth behind companion planting.
What is companion planting?
According to the dictionary, companion planting is the close planting of different plants that enhance each other’s growth and pest protection.
“Companion planting is the practice of planting different crops in close proximity to each other 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 planting certain plants next to each other has many benefits.
Why companion plant?
- Tall plants provide shade to the shorter plants that do not withstand the afternoon sun.
- Tall plants with strong stalks provide support for climbing crops.
- Short plants with broad 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 the growth of other plants.
Does companion planting work?
Unfortunately, many companion planting benefits mentioned above have no scientific evidence to support them. For example, nothing proves that planting alliums next to beans will prevent the latter from growing. Yet, 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 in the name itself. The expression “companion planting” seems too broad 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 to say 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 it, as a rule, was somewhat stressful. Most of the pairs mentioned would not work in my growing zone. It is more helpful to look at companion planting from the angle of intercropping.
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 difference. Intercropping does not limit the crops you can grow together. Instead, it is about using the space wisely and getting more harvest from it.
We may consider intercropping inclusive of companion planting with a focus on biodiversity.
Intercropping vs. companion planting
While companion planting considers plants’ influence on each others’ growth, intercropping is about smartly using planting space. For example, we are unsure if planting basil between tomato plants will make them tastier, but 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 will compete for the same underground space.
According to Mrs. Linda Chalker-Scotts, Extension Agent with Washington State University, “traditional companion planting charts have entertainment, and not scientific, value.“
What is the downside of companion planting?
The primary downside of companion planting is the belief that a gardener has to stick to the chart for it to work. In addition, it is rather stressful for a new gardener to figure out which plant goes with which.
Another negative point is that many of the pairings in the chart are not possible in warm climates where there are two growing seasons. For example, take a look at the bean companion plant chart:
|Beans||Beets, carrots, chard, cabbage, corn, cucumbers, peas, radishes||Garlic, onions||Nasturtiums and rosemary deter bean beetles|
In the growing zone 8b, cucumbers are the only crop that can companion the bean; 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 instead add it to the landscape than put it in the veggie garden.
Most common companion plants
Why are some plants seen as enemies to others?
There is no war between plants, but there are bad combinations. But, again, it all goes back to intelligent 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: 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 diseases. It is good to plant them away from each other to avoid cross-contamination.
- Imbalanced feeding: planting two plants that feed on the same primary nutrient may compete against each other. Better plant complementary plants for equal
- Overwatering and underwatering: Grouping plants according to their water requirements is essential. 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 to outline the raised bed instead of a physical grid.
- Plant basil between peppers, tomatoes, and eggplants. There is no need to dedicate a unique bed for your basil; it grows well even when slightly shaded by these plants.
- Plant sprawling winter squash in between beans, 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.
If you have been using companion planting and it has been working for you, so be it. However, if you are starting a garden, I advise you to keep it simple by only planting suitable crops for the season.
It is best to experiment and not limit yourself. Gardening is an adventure in 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