Over the past couple of years, I’ve been learning more about companion planting and all of its benefits. It’s a cool practice, so I put together this guide. Here are the top 10 benefits of companion planting.
- Boosts Pollination
- Repels Pests
- Prevents Weeds
- Fixes Nitrogen
- Amends the Soil
- Protects the Soil
- Provides Shelter
- 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!
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1. Boosts Pollination
By planting companion plants, you’re inviting many pollinators such as bees, butterflies, and hummingbirds. Most of these animals are attracted by the flower’s color and scent, but bee’s can also sense electric fields around the flowers.
These pollinators harvest nectar from flowers as their main source of food and energy. In return, the pollen from the male flowers stick to the pollinator’s body. When these pollinators then visit female flowers, the pollen rubs off, fertilizing the female flower.
For many plants, this starts the transition from flower to fruit.
Fruits then attracts animals, which contribute nutrients in the form of manure and scatter the fruit’s seeds.
This not only helps plants ensure successful reproduction but provides new territories for plants 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 include common pests such as aphids, caterpillars, and snails.
While this might seem like a bad thing, these pests also attract predators such as lizards and birds, which keep the pests’ population in check and promotes biodiversity in the food chain.
This biodiversity often creates a positive cascading effect for the rest of your 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 (growing only one type of crop, such as corn), as there’s no genetic difference, or barrier, of other types of plants to stop or slow the pests.
Companion plants repel pests by releasing a specific chemical or a strong scent from its leaves, flowers, or roots.
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 its 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, which are a natural predators of aphids.
Depending on your needs, repelling pests might be more important than things such as increasing pollination.
Another benefit from companion plants repelling pests is that you don’t need to use sprays or chemicals nearly as much (if at all).
For more pest-repelling companion plants, visit my other post: 7 Companion Plants That Repel Pests
3. Prevents Weeds
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, which vine and expand 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 pruning clippings from companion plants as mulch to further suppress the weed’s growth and seed bank.
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 adding nitrogen to the soil.
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 promote 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, clover, etc.) are the best nitrogen-fixing plants, which is a primary reason why they’re one of the companion plants 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
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 such as lichen, fungi, grasses, and nitrogen-fixers.
Pioneer plants are specialists at surviving in difficult conditions while amending the soil and paving the way for other, more sensitive plants (such as fruit trees) to grow.
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.
More specifically, mulches can be made from the clippings of just about any plant. Some companion plants such as comfrey grow quickly and their 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 such as 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 (thanks in part to their nitrogen-fixing ability).
Here are some effective cover crops you can use, no matter your size of land:
- Annual Ryegrass
A common issue with monocropping is that the crops out in a large field are not being sheltered from the harsh sun, wind, hail, or other extreme weather events.
An example of companion planting for shelter is to plant grapevines under an oak tree. By doing this, the oak tree is not only protecting the grapevines from sun and wind but creates a trellis for it to climb, as well as a moist climate for the grapes to get more water.
Another example would be growing a cucumber along a trellis to shade a tomato plant on the other side.
8. Provides a Living Trellis
Many thinner plants, such as beans prefer to vine vertically, to avoid competition with heavier ground covers 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 such as oak trees 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.
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.
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 on 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?
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 the 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 are 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 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.
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