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Home » Best Companion Plants: What to plant with Onions in your garden

Best Companion Plants: What to plant with Onions in your garden

Best Companion Plants: What to plant with Onions flowers, herbs, and veg


Onions are a great addition to any garden because they are natural pest repellents. They also have a long growing season, so you can plant them early and enjoy their freshness all summer long. The best onion plant companions are members of the cabbage family. Onions naturally repel pests that love cabbage family plants: cabbage loopers, cabbage worms, and cabbage maggots. Onion also naturally deter aphids, Japanese beetles, and rabbits. Good companion plants for onions are any plants that often fall victim to them- such as tomatoes, peppers, eggplant, strawberries, and roses.

Onion companion planting – with vegetables

Onion companion planting is a traditional practice where gardeners plant onions with other vegetables, usually carrots. The theory behind this practice is that the smell of onions will deter carrot root fly from the carrots while the smell of carrots will help to deter onion fly from the onions. There is no scientific evidence to support this claim, but some gardeners are convinced of its benefits, while others are less sure.

Other Alliums

Onions are a type of allium, and there are many other types of alliums. When you grow onions alongside other alliums, you can rotate crops more easily. They are similar because they like the same growing conditions. However, when it comes to alliums, crop rotation should be implemented to avoid disease and pests.


Brassicas are a group of plants that include broccoli, cabbages, cauliflower, kale/ collards, kohlrabi, mustard, and pak choi (among others). They are often grown together because they have similar cultural needs and benefits. For example, onions are often planted with brassicas because there are benefits to having them both in the garden- the onions may affect the flavor of the brassicas but also help to deter pests. However, you should avoid planting turnips with onions because the onions may affect the flavor and root growth of your turnip crop.


There are a few things you can do to help protect your carrots from being eaten by the dreaded carrot fly. One is to plant onion around them – onion is a plant that helps repel the pest. Another is to interplant onions with your carrots – this will help confuse the carrot fly and make it harder for them to find your carrots. Finally, remember that carrots are heat sensitive and solanine is a natural insecticide – so if you’re having trouble with pests, consider adding some onions to your garden!


Another root crop that can work well alongside onions is parsnips. Parsnips are a sweet and nutty-tasting vegetable that grows well in cooler weather. They can be harvested later than other root crops, such as carrots, beets, and radishes, and help to extend the harvest season. Parsnips also help in pest control by attracting beneficial insects to the garden.


Root crops and alliums, like onions, won’t compete for nutrients too excessively. Onions are great partners with beets – they protect from insect pests like aphids and sugar beet-flea beetles.


Tomatoes are a popular garden plant because they are relatively easy to grow and come in a variety of colors and sizes. One thing to keep in mind when planting tomatoes is that they need plenty of suns – at least 6 hours per day. They also benefit from being planted near onions, garlic, chives, and basil plants. These plants all have a strong scent which helps to repel pests like aphids and Japanese beetles.


Potatoes are a popular vegetable that can be grown in a garden. They should be planted 4-5 apart and in rows 12 inches apart. Evidence has suggested that planting onions near potatoes can reduce pest problems. Onions should be planted no more than 1 deep.


Lettuce is a versatile plant that can be grown in many different ways. It can fit in around other plants and help protect them from pests. Lettuce can also be grown with other vegetables, such as onions, and it will not take up much space. When planting lettuce, sow the seeds while the bulbs are still small and then transplant them when they begin to bulb out. Radishes work well with onions and lettuce.

Onion companion planting – with herbs

Companion planting is a great way to keep pests away from your plants. In this article, we explore the benefits of companion planting with onions and herbs. Specifically, we look at how parsley and mint can help ward off onion fly maggots. Onion fly maggots are a common pest that can devastate an onion crop. Mint is a fast-growing plant and can quickly take over an area, so it is important to contain it in a container if you choose to use it as a companion plant.


Dill is a common herb that is often used in cooking. It has the benefits of onion growth, meaning it can help to improve your overall health. Dill can be used in different ways in your kitchen, such as in salads, dressings, and dips. It is also one of the best culinary herbs and can add flavor to many different dishes.


Parsley is a herb that is very similar to carrots. It has a long stem with green leaves and a small white bulb. Onion and Parsley can be grown together in the same garden bed, as they have complementary needs. There are many benefits of growing parsley with onions, including improved flavor, increased pest resistance, and improved soil health.


Mints are a beneficial companion plant for onions. They repel insects and can help to keep the onion bed healthy. However, mints can be prolific growers and take over the bed if you let them. To prevent this, be sure to baffle the insects with the pungent smell of mint and trim back any excess growth regularly. This guide will help you grow mint without fear!

Pigweed (Amaranth)

Pigweed, also known as Amaranth, is a dynamic accumulator. This means that it can draw up nutrients from deep in the soil and make them available to other plants. This makes pigweed beneficial in vegetable beds and for crops like onions that need strong roots to grow well. One example of how pigweed can be used beneficially is in an onion bed. The onions will benefit from the extra nitrogen and phosphorus that the pigweed pulls up from the soil.

Sow Thistle

Sow thistle is a weed that is often considered to be harmful. However, it can actually be beneficial for onions in a similar way to other deep-rooted plants. These plants can be chopped and dropped to return nutrients to the soil.

Onion companion planting – with flowers

Onion companion planting is a great way to deter pests and diseases from attacking your onions. There are a number of flowers that you can plant with your onions that will help keep them healthy. Some popular companions include alliums (which deter aphids and black-fly), chives (which also deter aphids and black-fly), and Chrysanthemums (one of the most popular fall flowers). For more information, see our guide to planting roses.


Chamomile is a great companion plant for onions because it has antibacterial and antifungal properties that help improve the flavor of onions. Additionally, chamomile attracts beneficial pollinators with its sweet fragrance.


Marigolds are a great companion plant to onions because they are known to suppress nematodes in the soil. Nematodes are a type of parasite that can attack and kill onion plants. Additionally, marigolds have a strong scent which can act as a natural deterrent against these pests.


In the case of onions and roses, planting onions near roses helps to protect the roses from pests. The strong scent from the onions masks the scent of the roses, which confuses pests and deters them from attacking. Additionally, planting onions amongst rose plants helps to repel pests from both plants.

What not to plant with onions


There are a number of companion plants that you can plant with onions in your garden to help improve their growth and health. Some plants that work particularly well with onions include peas, tomatoes, and marigolds. Basil and tomatoes are specially made to go together – the two plants complement each other’s flavors and aromas, and both benefit from being grown close to each other. Marigolds also have pest-repelling properties, making them a good choice for gardens with onion crops.


Some plants grow well with onions when planted in the garden. Beans are not one such plant; they will grow up the cornstalks, providing support and also adding nitrogen to the soil. Additionally, marigolds, nasturtiums, rosemary, and summer savory have been found to improve the growth rate and flavor of both crops when planted together. However, it is best to keep these plants separate to avoid competition for resources.


Companion plants are plants that help other plants grow and thrive. There are a number of different companion plants that work well with onions, including asparagus. Asparagus, however, should not be planted near onions as the onion will stunt the growth of the asparagus plant. Additionally, the flavor of the asparagus may be affected by proximity to onions. For this reason, it is best to keep alliums in different beds or growing areas from your asparagus crop.


Companion plants are plants that are planted near other plants in order to benefit them. They can provide nutrients, attract beneficial insects, or deter pests. Onion growers have long been advised to plant sage as a companion plant, as it doesn’t stunt the growth of onions and has other benefits. However, recent research has shown that not all types of sage work well with onions – only cultivars of Salvia officinalis (common sage) should be used.

Where to plant onions in the garden?

In most cases, onions like the soil to be fairly moist and full of nutrients. This can lead to problems in areas with hot summers or cold winters.

The best time to plant onions is during the fall.

What vegetables should not be planted near onions?

It is best to plant vegetables that grow in different soil types, such as tomatoes and potatoes, near onions.

What do you interplant with onions?

“Intersplanting” is the process of planting two or more crops together in one field. The most common interplanting are corn and soybeans, but other crops like wheat and oats are also frequently mixed with other crops.

Can you plant onions with tomatoes?

Yes, you can plant onions with tomatoes. However, there are some risks involved in planting both of these vegetables together.

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