Onion Companion Plants: Full List of Pairings
Onions are one of the easiest vegetables to grow and store long-term. While they’re pretty self-sufficient, planting them with the right onion companion plants can make a big difference in yield and health – not only for your onions, but for the companion as well!
A good companion plant can minimize pest damage, deter disease, maximize garden space, and even make your onions taste better! Here is a full list of great companion options for your onions, along with a few vegetables and herbs you should avoid planting anywhere near your onion crop.
Full List of Onion Companion Plants
Unless otherwise noted, the following plants should be planted near or in-between proper rows of onions. You can also try mixing them all in one growing area through interplanting.
Vegetables to Plant with Onions
• Beets and Carrots – Planting beets and carrots near onions (but not too close – they’re both root vegetables, after all) can help deter diseases and pests, like the carrot fly.
• Broccoli, Cabbage, Cauliflower, and Kale – Some of the best onion companion plants are from the brassicas family. These include broccoli, cabbage, cauliflower, and kale, among others. Planting a member of this group with your onions can maximize garden space and minimize pest damage. I like to plant a row of broccoli in the middle of one of our beds, then plant two rows of onions on either side.
• Lettuce and Spinach – Lettuce and spinach won’t compete with your onions for nutrients or root space, and the smell of the onions can deter some pests.
• Peppers and Tomatoes – Onions are thought to improve the flavor of tomatoes and peppers, as well as confuse pests.
• Swiss Chard – Planting swiss chard near your onions can help retain valuable ground moisture for the onions.
Herbs to Plant Near Onions
• Chamomile and Summer Savory – Both chamomile and summer savory can improve the flavor of your onions by making them sweeter.
• Mint and Parsley – Planting mint or parsley near your onions can keep onion flies away.
Other Plants to Pair with Onions
• Marigolds – Marigolds can attract helpful insects that help onions grow, just like the flowers do for tomatoes.
• Strawberries – It’s thought that planting onions near your strawberries can improve the strawberries’ flavor, as well as possibly prevent pests from eating the berries.
What NOT to Plant Next to Onions
Some plants should be placed far away from onions. Common reasons are because they’re in the same family and can share diseases, will compete for root area with your onions, or will otherwise stunt the onion crop’s growth.
Vegetables to Avoid with Onions
• Asparagus – Growing onions and asparagus together can stunt the growth of both plants – asparagus will grow too large and leave the onions with too little light, and the onions will grow into the asparagus’ delicate root system and hurt the perennial roots when pulled in fall.
• Beans and Peas – Both beans and peas produce chemicals that are harmful to some other plants, including onions. They may stunt each other’s growth if planted in close proximity, and onions may negatively affect the flavor of your legume crop.
• Chives, Garlic, Shallots, and Other Onions – Chives, garlic, shallots, and other onion family members can share a common pest known as onion maggots. Planting them all closely together can encourage the bad bugs.
• Turnips – Turnips compete with onions for root space, and the onions can affect the flavor of your turnip crop.
Other Plants to Avoid
• Sage – Sage requires different growing conditions and may stunt the onions’ growth.
Happy Onion Companion Planting!
With these tips in mind, you should be able to plan onion companion plants into your garden to maximize space and plant health.
Looking for more companion planting tips? Check out the full list of potato companion plants.