13 Companion Plants For Onions

Companion planting is a gardening technique that involves planting different crops close together to enhance their growth, health, and productivity. One popular vegetable for companion planting is the onion.

Onions are known for their pungent aroma and strong flavor, which can help deter pests and make them a valuable addition to any garden. Growing onions alongside other compatible plants can not only improve the health and yield of the onions themselves but also benefit their neighboring plants.

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Benefits of Companion Planting with Onions

Pest Control

Companion planting with onions can help deter various pests from your garden due to their strong scent.

For instance, planting onions near brassicas such as cabbage, cauliflower, and broccoli helps keep insects and rodents at bay. Onions also confuse pests like aphids, protecting plants like tomatoes and peppers from damage.

Improved Growth

Certain companion plants can improve the growth and yield of onions and nearby plants. For example, planting onions alongside cruciferous vegetables, such as broccoli, cabbage, cauliflower, and kale, can maximize planting space and benefit each other’s growth.

This practice allows gardeners to make efficient use of garden space while increasing their harvests.

Enhanced Flavor

Onions have been known to enhance the flavor of some plants, particularly tomatoes and peppers. By planting them together, the taste of the fruits can be improved not only in hot peppers but also other varieties.

Companion planting with onions can make the produce from your garden even more delicious.

Nutrient Management

Companion planting with onions can improve soil quality and help manage nutrients in the garden. Certain plant combinations, like onions and strawberries, can boost the overall health of the soil and plants growing nearby.

This practice is beneficial for maintaining a balanced garden ecosystem and giving plants the nutrients they need to thrive.

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Best Companion Plants for Onions

Vegetables and Legumes

Onions pair well with many vegetables and legumes, enhancing their growth and protecting them from pests. Some great companions include:

• Carrots: Onions help repel the carrot fly, so planting alternate rows of carrots and onions or surrounding carrots with onions keeps the pests away.
• Lettuce: Onions can minimize the risk of infestations like aphids and slugs in lettuce plants.
• Cabbage, broccoli, and kale: Brassicas like cabbage, broccoli, and kale benefit from onions’ pest-repelling properties, particularly with cabbage worms and loopers.

On the other hand, you should avoid planting onions near tomatoes, peppers, and asparagus, as these plants may negatively impact onion growth and overall health.

Herbs

Herbs can also make excellent companion plants for onions. Some good pairings include:

• Chamomile: This herb helps boost the growth and flavor of onions.
• Sage and dill: These aromatic herbs repel pests that could damage onions.
• Parsley: This herb attracts beneficial insects that help control pests near onion plants.
• Mint: The strong scent of mint can also deter pests from attacking onions, but it’s important to remember that mint can be invasive, so consider planting it in a container to prevent it from overtaking the garden.

It’s important to note that garlic and leeks, despite being part of the Allium family like onions, don’t make ideal companions due to their competition for nutrients and water.

Flowers

Flowers are not only decorative but can also benefit onions by attracting pollinators and repelling pests. Some of the best flower companions for onions are:

• Marigolds: These bright flowers help deter insects like nematodes and aphids, benefiting onions and their surrounding plants.
• Roses: Roses may deter pests from attacking onions, while onions can help protect roses from common rose pests like aphids.
• Strawberries: Although onions don’t benefit directly from strawberries, the onion smell masks the berries, keeping pests away and enhancing the growth and health of the strawberries.

By combining onions with compatible vegetables, herbs, and flowers, you can create a beautiful and diverse garden while also preserving the health and growth of your onions.

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Plants to Avoid Pairing with Onions

Chemical Incompatibilities

Even though onions have many beneficial companion plants, there are specific plants that should not be planted together with onions.

Spinach

Spinach and onions are chemically incompatible, meaning they can hinder each other’s growth when planted together. This is due to the different nutrient requirements and the potential of competing for resources, which can lead to reduced growth or health of both plants.

Eggplant

Similarly to spinach, eggplant also shows incompatibility when planted near onions. Their chemical interference can lead to undesirable growing conditions and may limit the potential of both plants.

Potatoes

Planting onions and potatoes together can have a negative effect on both plants. This is mainly due to the fact that they share some common pests, such as root maggots and wireworms. Furthermore, onions can inhibit the growth of potatoes, leading to lower yields and potentially unhealthy plants.

Flavor contamination is another reason why you should avoid planting certain plants near onions. Due to the strong aroma of onions, the flavors of nearby plants can be adversely affected. This may result in the taste of their fruits or vegetables being altered, which is not desirable.

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Pests Repelled by Companion Planting

Companion planting with onions can effectively repel or distract various pests from causing damage to your garden. In this section, we will briefly discuss the common pests in onion gardens that can be managed by utilizing companion plants.

Common Pests in Onion Gardens

• Aphids: These small insects feed on plant sap and can cause damage to onions and other plants. Companion planting onions with plants such as tomatoes, peppers, and dill can confuse aphids and help keep them at bay.
  
• Rabbits: Rabbits enjoy feeding on various plants, including spinach and lettuce. By planting onions alongside these leafy plants, the pungent odor of onions can deter rabbits from foraging in your garden.
  
• Deer: Similar to rabbits, deer are also known for their voracious appetite for garden plants. The strong scent of onions can help deter deer from invading your garden.
  
• Cabbage worms: These green caterpillars can cause damage to brassicas (like cabbage) by feeding on the leaves. Onions can repel cabbage worms, making them a suitable companion for brassicas.
  
• Cabbage loopers: Another pest that feeds on brassicas’ leaves, cabbage loopers can be managed by planting onions nearby, as their scent acts as a deterrent.
  
• Japanese beetles: These invasive beetles feed on the leaves of many plants, including fruit trees and vegetables. Planting onions near susceptible plants can help ward off these destructive pests.
  
• Onion maggots: These pests feed on onion roots and can cause significant damage if left unchecked. Planting carrots near onions can help confuse these pests, reducing the likelihood of infestation.
  
• Cabbage maggots: Cabbage maggots attack the roots of brassicas and can stunt their growth. Like with onion maggots, planting onions near brassicas can help reduce the risk of cabbage maggot infestation.

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Wrapping up Companion Plants for Onions

By choosing the appropriate companion plants for your onions, you can create a more resilient and harmonious garden environment that helps to manage the common pests in onion gardens effectively.

Did you know there are tons of different types of onions? Check out our onion hub page to learn more about onion varieties as well as onion cultivation and culinary tips!