Companion Plants For Onions (the good, bad and the ugly)

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Are you hoping to cultivate an abundant and flourishing garden this season? Look no further than the incredible technique of companion planting. This method promotes robust development and natural pest control and creates a nutrient-rich environment that helps your plants grow stronger and healthier. With this comprehensive article covering the best companion plants for onions, you can experience the fantastic results of perfectly paired plant companions. So get ready to enjoy some incredible results and a beautiful and productive garden!

Some of the best onion companion plants that help boost their growth include cabbage, carrots, lettuce, strawberries, tomatoes, and select spices and herbs, such as chamomile, summer savory, and curry leaves. Avoid planting onions near chives, garlic, peas, beans, sage, and asparagus.

stack of white onions on wooden butcher's block with dark wood background

Get ready to watch your onions flourish with these expert companion planting tips, regardless of whether you’re an experienced or novice gardener. Discover the perfect plant companions that boost production and help protect against pests and disease while learning which plants to avoid. 

And while results always vary based on factors such as weather conditions and individual plant health, I’m confident that this article will help bring success to your gardening endeavors. So, let’s roll up our sleeves and start planting as we delve into the fantastic world of companion planting for onions.

Humble Highlights

  • Master the 5 key benefits of companion planting and how this age-old practice can help your garden prosper and produce more come harvest so you can let Mother Nature do the heavy lifting.
  • Discover the 12 primary companion plants of onions to enhance the flavor of your vegetables and protect your garden like a seasoned pro!
  • Better organize your garden BEFORE you sow by learning what not to plant near onions to promote better growth and health throughout your green space.

What Is Companion Planting 

Companion planting is an age-old gardening practice that involves planting different types of crops together in the same area to maximize the use of space, nutrients, and water. The concept behind companion planting is that certain plants can benefit each other by enhancing growth, improving flavor, and providing natural pest control.

This ancient practice is becoming increasingly popular among home gardeners as it can help improve their garden’s overall health and productivity while reducing the need for chemical fertilizers and pesticides. 1

companion plants for onions and garlic
Improved soil structure, weed suppression, and attracting beneficial pollinators to your garden are just some of the fantastic benefits companion planting offers.

One of the main benefits of companion planting is that it can help control pests and diseases in a natural and environmentally friendly way. For example, some plants have natural repellent properties that can keep harmful insects away from crops, while others can attract beneficial insects, promoting vitality throughout your growing area.

Certain plants can also help suppress the growth of weeds, which can compete with crops in your garden beds for nutrients and water. Using companion planting techniques, gardeners can create a healthier, more sustainable practice that benefits plants and wildlife.

Companion planting is a time-tested and effective technique for maximizing a garden’s productivity while promoting a healthy and sustainable ecosystem. With the right companion plants and proper care, gardeners can create a thriving and diverse environment helping their crops produce more. As the popularity of companion planting continues to grow, it’s clear that this timeworn gardening tradition is as relevant and effective today as it was centuries ago.

What Are The Benefits Of Companion Planting 

There are many valuable benefits of companion planting that any gardener can take advantage of, including:

  • Masking the scent of vulnerable vegetable plants from harmful insects
  • Maximizes garden yields – even if space is limited 
  • Enhances the flavor of your vegetables 
  • Sustainable soil management 
  • Provides shade and structure to your garden vegetables 
best and worst companion plants for onions
Sowing friendly garden neighbors together in your green space promotes health and vitality for not just your garden but for the ecosystem at large.

Let’s look at these conveniences and see how to implement them in your green space today. 

Masking Scent: Dettering Pests, Attracting Good Ones

Certain plants can emit odors that help mask the scent of insect-desirable vegetables and protect them from damage and even death. By planting these odor-masking plants near vulnerable vegetables, you can create a natural, invisible barrier that promotes an effective pest control system supporting the health and well-being of your garden plants. For example, planting onions or garlic alongside carrots can deter the notorious carrot fly, a common pest that can decimate crops.

Aside from repelling pests, some plants can attract beneficial insects such as bees and butterflies, dragonflies, and ladybugs, which help to transfer pollen between plants, promote healthy growth, and prey on the more damaging garden insects.

companions plants for onions
Butterflies, bees, and dragonflies all help promote pollination throughout your garden, so consider including plenty of flowers in your green space.

For example, planting marigolds throughout your garden can help attract ladybugs, natural predators of aphids and spider mites, while providing a desirable nectar source for bees. Similarly, planting herbs such as dill, fennel, and parsley can attract beneficial insects like hoverflies, which prey on aphids and other pests. 2

Small Garden, Big Harvest

Another advantage of companion planting is making the most of limited garden space while increasing harvests. By carefully selecting plant combinations, gardeners can use every inch of available space to their benefit. This means that even tiny gardens, like those found on urban rooftops and balconies, can be highly productive, yielding a variety of crops.

Additionally, companion planting can benefit gardeners with limited space or those who wish to grow a diverse range of crops. For example, planting compact vegetables such as cherry tomatoes, peppers, and bush beans alongside taller plants like corn or sunflowers can help maximize space while providing support and shade to smaller plants.

Humble Tip:

Companion planting can also allow for intercropping, where crops with different maturity times are grown in the same space. This practice allows for a staggered harvest, providing a continuous supply of fresh and delicious produce throughout the growing season. For instance, fast-growing radishes can be planted alongside slower-growing broccoli or cabbage, allowing for two different crops to be harvested from the same space at various times.

The Secret To Tasty Harvests 

Planting certain herbs and plants alongside fruits and vegetables can enhance their flavor and contribute to a more flavorful harvest. For instance, using bee balm has been found to improve the growth and flavor of tomatoes. Other herbs, such as basil and dill, can also enhance the flavor of tomatoes and other nearby vegetables.

In addition to bee balm, several other herbs and plants can enhance the flavor of fruits and vegetables. For example, planting mint alongside strawberries can give your berries a delicious yet subtle minty taste. Likewise, chives and garlic are also great companions for tomatoes, as they serve double-duty by repelling pests and enhancing their flavor.

Sustainable Soil Management: From Soil Health To Plant Health

Companion planting is more than just growing plants side by side. It’s also a strategy that helps improve your garden’s soil health and vitality. This method involves pairing plants that work well together to create a natural ecosystem that fosters healthy growth and minimizes pest infestations.

One example is planting nitrogen-fixing plants like peas and beans with nitrogen-hungry plants like tomatoes and corn. Nitrogen-fixing plants can convert nitrogen from the air into a usable form for plants. 3

companion plants of onions
Companion planting helps encourage soil fertility, whether by adding nutrients like nitrogen-fixing legumes or helping to break up compacted dirt, providing needed air and water to your plants’ roots.

Aside from nitrogen fixation, companion planting can improve soil fertility and structure. For example, planting legumes like clover can help reduce soil erosion and improve soil fertility by adding organic matter. Meanwhile, deep-rooted plants like comfrey or dandelion can help loosen compacted dirt, allowing necessary air and water to penetrate the soil more easily.

Home gardeners can enhance their soil’s health by adopting companion planting techniques, producing more productive and healthier plants. Additionally, healthy soil reduces the need for synthetic fertilizers, which can harm the environment through runoff.

Physical Space Interaction: Plants As Trellises 

Combining tall and short plants in the same area to provide shade and structure is commonly known as “physical space interaction.” By utilizing this method, you’ll help promote the health and productivity of your entire garden. 

can you plant onions with flowers
Growing plants of different sizes and root depths help crowd out unwanted weeds, keeps soil cool and moist, and adds an aesthetic intrigue to any home garden.

It involves cultivating plants on different levels to provide ground cover to crowd out weeds, provide necessary shade, or serve as a natural climbing trellis for those vegetable plants that vine, like pole beans. For example, planting a tall corn stalk with pole beans is a great way to utilize physical space interaction. While the beans create natural ground cover by pushing out weeds, keeping the soil moist, and providing nitrogen, the corn offers shaded relief and a climbing trellis for the beans.   

But the benefits of this technique go beyond just support and structure. Companion planting also helps keep the taller plants upright, making them less likely to fall over and damage the shorter plants. Plus, it’s a great way to utilize space and maximize yield, especially if garden space is limited. 

Companion Plants For Your Onions

There are several common companion plants for onions, including:

  • Cabbage
  • Carrots
  • Leeks
  • Lettuce
  • Tomatoes
  • Strawberries
  • Chamomile
  • Summer Savory
  • Curry Leaves
  • Pigweed
  • Beets
  • Swiss Chard
companion planting for onions and garlic
Beets, carrots, and tomatoes are just a few tasty and popular vegetables that make friendly garden companions with onions.

Let’s check out each of these plants and herbs to see why you, too, should be incorporating these friendly neighbors near your onion patch. 4


Cabbage belongs to the brassica family and has a symbiotic relationship with onions. As we all know, cabbages are highly susceptible to infestations by cabbage worms, loopers, and maggots. However, planting onions alongside cabbage can effectively repel these destructive pests, ensuring your cabbage crop’s health and productivity while providing overall garden sustainability.


Onions and carrots make great companion plants as they don’t compete with each other for soil nutrients. In addition, onions have a fibrous root system that can withstand any accidental damage to the roots or leaves, making them an ideal plant to grow alongside carrots, which have deep roots that dive deep into your garden bed.

spring onion companion plants
Carrots are a popular backyard crop and create a wonderful relationship with onions as they don’t compete for soil nutrients.

Planting onions around your carrot patch can also effectively repel the infamous carrot fly that can cause catastrophic damage to your plants. Incorporating onions into your garden can create a natural barrier to deter this onerous pest from attacking your carrot crop and safeguard your harvest.


Onions and leeks create a dynamic duo in the vegetable garden. They share similar environmental needs, such as soil type and sunlight, and require similar nutrients to grow and flourish.

Onion flies are a common pest that can destroy your onion crop. Fortunately, when leeks are placed in proximity, they can emit an odor that confuses the flies, making it more difficult for them to locate your prized onions. In addition, this makes it less likely for onion flies to lay their eggs, reducing the risk of infestation and crop loss throughout your garden. 5

Some of the best companion plants for onions have different rooting systems and won’t compete for vital soil nutrients and resources. Here’s a great video that explains some of the best friendly garden neighbors you can plant alongside your onions and what pests the humble onion can deter.

Onions make great garden protectors as they help deter all sorts of harmful and dangerous insects, like aphids, carrot flies, and cabbage maggots.


Lettuce and onions are two vegetables that make friendly garden companions as they help you maximize planting space and resources. While both crops require similar growing conditions, enjoying the full sun and fertile soil, they do not compete for resources due to the unique characteristics of onions.

Onions have short roots that do not extend deeply into the soil, meaning they do not compete with lettuce for nutrients and water. Instead, they can be planted in the same area as lettuce, allowing you to maximize the planting space in your garden while increasing your overall harvest.


Tomatoes and onions are a classic flavor pairing in many cuisines, and when grown together, they can enhance each other’s taste and aroma, producing a flavorful harvest. 

are onions good companion plants for tomatoes
Onions can help enhance the taste of your backyard tomatoes, making this advantageous combination virtually a no-brainer for many home gardeners.

Onions, on the other hand, also have natural pest-repelling compounds that can help deter common garden pests like aphids. The strong scent of onions is particularly effective in keeping aphids at bay because they find the aroma unpleasant and tend to avoid the area. This can help protect your tomato plants from infestation and ensure a healthier and more productive crop. 6


Strawberries are a delicious and nutritious crop enjoyed by many gardeners. But unfortunately, these tasty morsels are pretty vulnerable to pests and diseases. These sweet little fruits are particularly prone to aphid attacks, which can cause significant damage to the plants and affect the health and productivity of your harvest. Fortunately, onions can provide a natural and effective solution to protect your strawberry crop, as they create a barrier around your strawberry patch. 

Humble Tip:

Onions don’t necessarily need to be grown in the same growing bed to be a helpful companion. Consider developing a few in pots by strategically placing them around your green space where needed. The onions will still provide all the benefits but now become mobile, helping plants anywhere in your garden that pests may attack. 

Fortunately, onions are easy to grow. They prefer highly fertile yet slightly acidic soil for optimum growth. So, include a healthy dose of organic matter, like compost, to keep them happy throughout their lifecycle. Additionally, ensure your containers are well-draining, and place your onions in full sun. 

Spices And Herbs (Chamomile, Summer Savory, Curry Leaves)

Chamomile possesses many beneficial properties, including antibacterial and antifungal properties, which can be particularly advantageous when planted near onions. But it’s not just the medicinal benefits that make chamomile an ideal companion plant for onions. Chamomile can also enhance the flavor of onions, making them more palatable and enjoyable.

Similarly, summer savory is another valuable companion plant for enhancing the taste of onions. This unique herb can lend a sweet and tangy flavor to your onions, improving their overall taste and making them a desirable addition to your meals. Summer savory also attracts beneficial insects, such as bees and parasitic wasps, which can help pollinate your onions and protect them from harmful pests.

Amaranth Family (Pigweed, Beets, Swiss Chard)

Pigweed is often considered a weed but can be a valuable asset to your garden. This annual plant has the unique ability to accumulate and retain nutrients beneficial to your onions. As a result, it can help draw these essential nutrients from the soil and transfer them to your crop. Further, the nutrients that pigweed accumulates in the subsoil can be used by your onions, which leads to healthier plants and better yields come harvest.

best companion plants for onions
Swiss chard makes for nutrient-dense leafy addition to any garden, and when grown alongside onions, it helps promote welcome shade and maintains soil moisture.

Beets can help protect onions from thrips, a commonly stubborn pest that can damage and destroy onion crops. Growing beets alongside onions can create a natural barrier that deters thrips. In addition, beets can serve as a natural deterrent for additional garden pests, including aphids, sugar beet-flea beetles, and even larger animals like rabbits and deer hoping to steal a green snack. 7

Swiss chard is a leafy vegetable that offers many benefits to the garden, mainly when grown alongside onions. The large leaves of Swiss chard provide a natural shady cover that can help maintain moisture levels in the soil, which is particularly beneficial for onions. Onions have short roots that require continuous moisture to grow and develop their bulbs, so the presence of Swiss chard can help ensure that the soil remains moist and fertile.

In return, onions can also help repel bugs and insects, like aphids and cabbageworms, that may harm Swiss chard leaves. These insects can be a real threat to the health and productivity of your Swiss chard, but onions produce a strong odor that many insects find unappealing.

Plants To Avoid Growing Near Onions 

Several plants are grown best elsewhere in the garden as they don’t make great companions, including:

  • Alliums (Garlic, Shallots, Chives, Scallions)
  • Legumes/Peas
  • Sage
  • Asparagus
bad companion plants for onions
Asparagus and peas are just a few of the vegetables that should be grown elsewhere in your garden and away from your onion patch.

Let’s discuss why these plant selections are best grown away from your onions. 

Alliums (Garlic, Shallots, Chives, Scallions)

Except for leeks, allium plants, such as garlic, shallots, chives, and scallions, are a staple in many gardens due to their delicious flavor, versatility, and nutritional value. However, it is crucial to be mindful of how these plants are grown in relation to each other. 

While alliums may thrive on the same nutrients, it is best to avoid planting them together to prevent resource competition. Furthermore, pests that may infest one type of allium plant, such as shallots or garlic, can quickly jump or transfer to your onions, leading to infestations, stunted growth, and disease that can damage your onions and significantly impact your harvest.

Humble Tip:

To promote a healthy and productive garden, consider providing allium plants some necessary space or plant them away from each other to prevent them from robbing soil nutrients. Giving them some room will help reduce the risk of nutrient competition and prevent pests from spreading between them, saving your sanity in the process.


While plants like beans and peas may be tempting to grow alongside onions, they can cause challenges due to their shallow root systems. You see, beans and peas require similar nutrients as onions, and their roots can quickly deplete the soil of these essential resources, leading to stunted growth and smaller onions. Plus, the competition for nutrients can also result in inconsistent growth patterns resulting in some onions not growing. 8

what not to plant with onions
To avoid uneven growth in your onions and unnecessary competition for essential soil nutrients, sow your beans and peas in a separate area in your garden.

However, it’s best to plant onions after harvesting these legume plants. This way, your onions can benefit from the nitrogen the legume plants produce and deposit in the soil. Onions are heavy nitrogen feeders, so this is a great way to give them the nutrients they need without risking competition from shallow-rooted plants.

Humble Tip:

Good garden practice dictates you rotate your crops each year to prevent nutrient depletion in the soil and prevent disease. Consider cultivating onions in the same area as you developed legumes and peas the previous year so they can enjoy the residual nitrogen left in the soil.


Sage and onions have different growing requirements, so they likely will not enjoy being friendly garden neighbors when planted together. For instance, sage requires dry but well-drained soil, while onions need moist soil for optimal growth. As a result, sage and onions may compete for resources when produced together, leading to stunted growth and lower yields for both plants. 

Additionally, sage has a strong scent that may repel beneficial insects and attract pests, potentially harming your onions. Therefore, planting sage and onions separately in the garden is advisable to ensure optimal growth and harvest. 9


Asparagus is a popular and nutritious vegetable often grown in home gardens. While it has many benefits, it is not an ideal companion plant for onions due to its shared nutrient need. Both asparagus and onions are heavy feeders, requiring plenty of nutrients to grow and produce a bountiful harvest.

good companion plants for onions
Because of its aggressive growth and feeding, asparagus should be grown in a dedicated area in your green oasis and away from your onion patch.

When grown together, onions and asparagus will compete for the same nutrients, leading to stunted growth and smaller yields. Asparagus, in particular, can be very aggressive in nutrient uptake, leaving little for nearby plants. Additionally, asparagus has a deep root system, making it difficult for other plants to access nutrients in the soil.


Companion planting is a game-changer for gardeners looking to maximize their crop’s potential. You can boost your yields, protect against pests, and enrich the soil with the right companion plants. For example, it’s a technique that can enhance onion growth by selecting plant companions that provide natural pest control, improve soil health, and enhance flavor. 

Some of the best onion companion plants include cabbage, carrots, leeks, lettuce, strawberries, tomatoes, chamomile, summer savory, pigweed, beets, and Swiss chard. But beware, not all plants make good companions for onions. Choosing your partners wisely is crucial to avoid competition for resources or unwanted visitors in your garden. Therefore, garlic, shallots, chives, scallions, legumes, peas, sage, and asparagus should all be grown elsewhere in your green space. 

Whether you are just embarking on your gardening journey or have years of experience, remember that the power of companion planting is at your fingertips. With the right combinations of plants, you can unlock a world of benefits, from natural pest control to enhanced flavor and soil health, providing immense value to your backyard garden and making endless – and tasty – possibilities. 

What companion plants do you grow alongside your onions in your garden? We’d love to hear about it! So drop us a line below in the comments and join the discussion!


  1. Cornell University, Cooperative Extension – Companion Planting
  2. ResearchGate – Companion Planting And Insect Pest Control
  3. Montana State University – The Science Of Companion Planting In The Garden
  4. Wikipedia – Onion
  5. Wikipedia – Allium
  6. Iowa State University, Extension And Outreach – Planting Onions In The Home Garden
  7. University Of California, Agriculture & Natural Resources – Pigweeds
  8. United States Department Of Agriculture – The Three Sisters Of Indigenous American Agriculture
  9. United States Department Of Agriculture, Forest Service – Why Is Pollination Important?

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