Over the past couple of years, I’ve been learning more about companion planting and all of its benefits. It’s a really cool practice, so I decided to put together this list and share it. Here are the top 10 benefits of companion planting.
- Boosts Pollination
- Repels Pests
- Prevents Weeds
- Fixes Nitrogen
- Amends the Soil
- Protects the Soil
- Reduces Evaporation
- Provides a Living Trellis
- Maximizes Space
- Produces More Food
Now, let’s take a look at each of these benefits in a bit more detail.
1. Boosts Pollination
Growing up in Orlando, Florida, I remember driving through nearby orchards full of blooming orange trees. The blossoms’ scent was so strong that it would almost follow you home. And this sweet smell isn’t just appealing to humans.
Pollinators such as bees, butterflies, and hummingbirds are attracted to flowers, usually by the flower’s color and scent, but some pollinators such as bees have a third way to track flowers—electric fields. The electric fields from flowers act in part as a billboard, and the bees can even use it to determine if a flower has been previously visited by another bee (source).
These pollinators then harvest nectar from flowers as their main source of food and energy. In return, the pollen from the male flowers sticks to the pollinator’s body. When these pollinators then visit female flowers, the pollen rubs off, fertilizing the female flower which, for many plants, starts the transition from flower to fruit.
Once fully developed, fruits are a convenient package of energy. They’re full of sugar and are usually designed to be eaten easily. The animal gets a tasty snack and the plant’s seeds are scattered (usually with plenty of fertilizer in the form of manure).
This not only helps plants ensure successful reproduction but provides new territories for them to grow. For example, when birds eat seeds and fly to migrate, they cover a large distance many hundreds of miles away. These new territories then provide even more genetic security for the plants. Overall, it’s a win-win for both the animal and the plant.
However, flowers not only attract pollinators but a host of other life. These other organisms can include common pests such as aphids, caterpillars, and snails. While this can seem like a bad thing, these pests also attract predators such as lizards and birds, which keep their population in check and promote biodiversity in the food chain.
As a result, this biodiversity often creates a positive cascading effect for the rest of the garden and surrounding areas.
To see more companion flowers, check out my other post: The Top 10 Companion Flowers for Gardens, Vegetables, & More.
2. Repels Pests
While some companion plants attract beneficial insects, others repel destructive ones.
Pests are notorious for decimating gardens, even within a single day. This is especially common with monocropping, as there’s no genetic difference, or barrier, of other types of plants to stop or slow the pests. It’s no wonder the first instinct we tend to have is to spray all of our plants.
Luckily, companion plants also come in handy for repelling pests. Typically, this is done by the roots putting out a specific chemical or a strong scent from its leaves and flowers.
Here are just a few of the pests that can be repelled by companion plants:
- Snails and Slugs
The most well-known pest-repelling companion plant is the marigold as it has the unique ability to deter nematodes through their roots. Nematodes are particularly destructive for potatoes but can harm many plants including tomato, pepper, eggplant, okra, cucumber, and squash (source).
Some other examples of the repelling ability of companion plants include lavender repelling snails and slugs with its strong scent, and nasturtium attracting aphids away from plants with its naturally sheltering leaves.
Additionally, marigolds, along with cilantro, geranium, and dandelion, are great at attracting ladybugs (a natural predator to aphids).
For many gardeners, repelling pests might be more important than other needs such as increasing pollination. And with companion plants, you often don’t need to use sprays or chemicals to reduce or eliminate pests, but instead, adapt permaculture (permanent-agriculture) based solutions such as ladybugs and other means.
For more companion plants that repel pests and diseases, visit my other post: 10+ Companion Plants That Prevent Pests and Diseases.
3. Prevents Weeds
Like pests, many weeds can be destructive in the garden. Generally, weeds tend to compete with other plants, sap nutrients from the soil, and provide refuge for pests.
However, not all weeds are bad. Dandelions are one of the most common “weeds”, but are actually one of the companion plants we’ll cover as they’re great at improving pollination and amending soil.
Other companion plants are also good at filling in spaces in the garden and providing ground covers to prevent weeds from growing.
For example, plants such as nasturtium, sweet potatoes, and strawberries are known to have runners, vining and expanding throughout the garden. By blocking out sunlight and growing space with their leaves, these companion plants often prevent weed seeds and seedlings from growing.
Other times, you can use clippings from companion plants as a mulch to further suppress the weed’s growth and seed bank.
4. Fixes Nitrogen
Nitrogen is one of the three primary nutrients plants need to grow. It’s a vital ingredient for most plants to grow their leaves, roots, and canopies (source). However, since most (if not all) plants require this nutrient, it can often become exhausted or eliminated from the soil.
This is where nitrogen “fixing” plants come in.
The roots of these plants are great at promoting bacteria that take nitrogen from the air, convert it into nitrates, and store it in the soil for other plants to use (source).
Legumes (beans, peas, and the like) are the best nitrogen-fixing plants, which is a primary reason why they’re one of the companion plants comprising of the Three Sisters. They provide the other two sisters, corn and squash, with extra nitrogen, boosting their growth and health.
Many other plants are also great at amending nitrogen in the soil, such as:
- Black Locust
5. Amends the Soil
Fixing the soil’s nitrogen isn’t the only way to amend the soil. Soil can also be amended to have better drainage, fungal life, and other nutrients aside from nitrogen.
When you’re working with poor soil, such as heavy clay or cracked and dry soil, one of the best ways to turn it around and build the soil is by using pioneer plants. Pioneer plants are specialists at surviving in difficult conditions while amending the soil and paving the way for other, more sensitive plants to grow.
In the book, The Hidden Life of Trees, German forester Peter Wohlleben shares how birch trees are pioneers in land and forests that are challenged. He mentions that birch trees not only grow well in poor conditions, but they take advantage of gaps in the forest canopy to capture more sunlight and grow faster than other plants.
However, while birch trees outcompete other trees in the short term, their quick growth often means they won’t live as long. So, after some time, the birch tree dies, opening the forest canopy again, providing not only sunlight, but now nutrients, mulch, and a habitat for other plants and animals to survive in areas that were previously devoid of much life.
But what if you don’t have a forest?
How can you amend a pasture’s soil with companion plants?
Gabe Brown, in his book Dirt to Soil, highlights how his conventional farm in North Dakota was struggling. Through lots of trial and error, he found the source of the issue was the quality of the soil. As he was previously tilling and overusing the land, he was accidentally exhausting his soil of its nutrients, beneficial microbes, and water-retaining qualities.
Once he stopped those practices and started focusing on growing the soil first, many of his farm’s challenges faded or went away completely. And a large part of his recipe was covering the land with mulch and cover crops.
6. Protects the Soil
Fixing nitrogen and amending soil are two helpful practices, but they’re not possible if the soil isn’t protected in the first place. Without sufficient coverage, the soil is prone to erosion which results in a loss of topsoil.
While this might not seem like an issue, 50% of the topsoil worldwide has been lost in the past 150 years (source). However, the good news is that companion planting helps create new topsoil.
Companion plants primarily cover and protect the soil in three ways: mulching, ground covers, and cover crops.
In summary, mulching involves using the fallen and pruned leaves and branches on top of the soil. Ground covers are using vining plants to cover the ground, such as sweet potatoes and grapes in part with other companion plants. And cover cropping is employing grasses and legumes to cover pastures.
More specifically, mulches can be made from the clippings of just about any plant. Some companion plants such as comfrey grow quickly and its pruned leaves make a good mulch. Banana plant leaves are also great as they cover a larger surface area of the soil.
Ground cover plants are similar to the practice of mulching, with the exception that they’re living. Because of this, your garden gets all of the benefits of mulching along with ground penetration (from the plant’s roots), extra nutrients, and more biodiversity. We’ve already touched on some effective ground cover companion plants such as nasturtium, sweet potatoes, and strawberries. However, vining squash, zucchini, and cucumbers also work.
Cover crops typically include grasses and legumes and are used to improve soil health by slowing erosion, retaining water, preventing weeds, and controlling pests and diseases. They’ve even been shown to increase crop yields. In the drought of 2012, corn and soybean farmers reported a 9.6-11.6% yield increase when they used cover crops, likely due in part to the cover crop’s ability to add 50-150 pounds of nitrogen per acre (source).
While many of you may not be growing corn and soybeans commercially on large farms, backyard cover crops have recently grown in popularity and have been shown to improve even small patches of land.
Here are some effective cover crops you can use, no matter your size of land:
- Annual Ryegrass
7. Reduces Evaporation
It seems that many areas of the US and the world are getting drier, forest fires are becoming more common, and water rations are being discussed in places such as California. In the last 1-2 years that I lived in California, I recall there being only about 2-5 days of rain.
All of this means that permaculture is becoming increasingly more important. Fortunately, companion planting is one of the permaculture solutions to reduce evaporation and keep the water in the soil.
The same companion plants that are used as mulches, ground covers, and cover crops can also be used to reduce evaporation.
Additionally, clippings and yard waste from these companion plants can be composted to further improve the soil’s richness and water-retaining ability. Every 1% increase in soil richness holds around 20,000 more gallons of water per acre (source). Sounds crazy, I know, but I checked the math and it’s true.
Along with companion planting, other permaculture solutions help drier regions including irrigating with greywater and establishing microclimates—have you thought about how an oasis can form in the desert?
Microclimates are also a great way to stretch your hardiness zone and grow a larger variety of plants. A great book that details microclimates and growing your own oasis, no matter your climate, is Gaia’s Garden: A Guide to Home-Scale Permaculture by Toby Hemenway.
8. Provides a Living Trellis
Many thinner plants, such as beans prefer to vine vertically, to avoid competition with heavier ground cover plants like sweet potatoes and squash. Beans would grow vertically on their own if they weren’t lacking a rigid stem. While you can buy and use wooden, bamboo, or aluminum trellises, living trellises are also a great option and one that’s multi-purpose.
Going back to the Three Sisters example, beans would have a difficult time thriving if it wasn’t for corn’s ability to act as a living trellis for them to vine up. In exchange, the beans increase the nitrogen in the soil while also anchoring the corn.
In places where growing corn isn’t feasible, other companion plants such as amaranth, sunflowers, and sunchoke can also function as living trellises. Sometimes, small trees make the best living trellises.
Compared to inanimate trellises, these living trellises provide other benefits such as increased pollination, food, and shade.
9. Maximizes Space
One of the main problems with suburban gardening is that you have a limited amount of space. In the US, this means an average of about 1/8 of an acre (source). However, many companion plants can be grown together to maximize your garden space.
For example, in food forests, companion plants are often grown in specific layers such as overstories and understories to capture as much sunlight as possible. Ideally, food forests allow little to no sun to reach the ground (similar to a healthy, real forest).
As a great example, James Prigioni from the popular YouTube channel The Gardening Channel With James Prigioni has grown an amazingly abundant food forest in his 1/3 acre backyard in New Jersey. He’s growing tons of plants together including apples, peaches, grapes, and tomatoes.
While it can take time, growing a food forest is an exciting way to grow a garden while getting the best efficiency in terms of space and harvest. We’ll cover more about food forests in another post titled How to Plant Companion Plants.
10. Produces More Food
Today, we often believe that the only way to grow more food is to add more chemical fertilizer. This has been the line of thinking since chemical fertilizers were invented in 1903 (source).
However, we’re now finding out that while these industrial fertilizers can help in the short term, they often have long-term consequences that ultimately turn living soil into dead dirt. And once the soil dies, it also has a series of negative cascading effects for the remaining plants and animals.
Clearly, agriculture was not also invented in 1903—it’s been largely successful for many thousands of years and across countless civilizations, so what did we do before chemical fertilizers?
Before 1903, in westernized culture, we still mostly practiced monocropping and hoped for the best. Hoping for enough rainfall, good weather, and no pest or disease damage. And this is one way of growing food.
However, in cultures that were more synchronized with nature, such as the Native Americans, crop rotation and intercropping were popular and effective methods. Again, the Three Sisters is a great example of their understanding of intercropping and companion plants.
And we can still bring these benefits into today’s age.
A recent study showed that planting companion plants alongside strawberries significantly increased yield and market quality of the berries—as much as 35% more fruits, and 32% more yield by weight (source).
In this study, the companion plant used was borage and specifically increased the number of pollinating flies for the strawberries. However, other flowering plants can have a similar effect, and benefit more than just strawberry plants.
Of course, the reason why many of us garden is to grow nutritious food, and companion plants are a helpful way to increase your harvests. Keep in mind that there’s not one specific way to grow more food from companion plants. A combination of the other nine benefits above will also result in healthier, more abundant plants and harvests.
Just about every plant benefits another plant. Even dandelions (too often thought to be just a weed) provide numerous mutual benefits such as adding nitrogen, boosting pollination, and amending soil.
Before jumping into companion planting, first decide which of the above benefits you’d prefer the most. For example, many gardeners focus on the amount of food their plants produce. Others may want the best pollination and biodiversity.
So, choose the primary benefits you’re seeking. If it’s all of them, consider ranking them based on importance.
Action Step: Refer to the list above and choose the top three benefits you’d like for your garden, or rank these benefits in your preferred order (feel free to add other benefits I may have missed).
While corn, beans, and squash are the most famous pairing of the companion plants, there are many others, all with their own benefits. And the best way to identify which plants are companion plants is to simply observe your garden.