Onions are low-maintenance neighbors that grow well with most vegetables
Onions don't compete hard for nutrients, they don't shade out shorter plants, and they actively repel some common pests. The best companions are plants that need different soil depths or nutrients than onions do — so you're using the same space without the plants fighting each other. Beets, lettuce, spinach, carrots, and herbs like dill and parsley all grow beside onions without problems. A few plants actually help onions grow better by keeping pests away or improving the soil.
The strategy is straightforward: use vertical space by pairing shallow-rooted plants with deep-rooted ones, and use time by planting fast-maturing crops between slower ones. A single raised bed can hold onions plus two or three companion crops if you stagger them by harvest date. This approach gives you more food from the same square footage without any plant suffering.
Key Takeaways
- Beets, carrots, lettuce, and spinach are safe to plant directly beside onions and use different soil layers so they don't compete.
- Herbs like dill, parsley, chives, and cilantro repel onion pests and take up minimal space in a raised bed.
- Avoid planting beans, peas, or other legumes near onions because onions can stunt their growth.
- Space onions 4 to 6 inches apart and give taller companions like dill room so they don't shade the onion bulbs.
- Marigolds and nasturtiums planted at the bed edges draw pests away from onions and are edible flowers you can harvest.
Root vegetables that share space without competing
Beets and carrots are the best root-crop companions for onions. Onions form bulbs in the top 2 to 3 inches of soil, while carrots and beets push deeper — carrots especially can reach 8 to 10 inches down. Because they're working at different depths, they don't pull nutrients from the same zone. Plant carrots and beets on a 3-inch spacing and onions on a 4- to 6-inch spacing in the same bed, and both will size up normally.
Radishes work the same way and mature in 25 to 30 days, so you can pull them out and replant the space with something else while your onions are still growing. Turnips are slower but also occupy a different soil layer. None of these root crops shade onions or attract the same pests, so there's no downside to mixing them. If you want a second crop from the same space, pull the radishes or beets early and plant lettuce or spinach in their place.
Leafy greens that use the space efficiently
Lettuce, spinach, and arugula grow in the top inch or two of soil and mature before onions are ready to harvest. Plant them between onion sets or transplants, and they'll be gone by the time the onions need room to bulge. Spinach especially tolerates the partial shade that taller onion foliage creates as it grows, so it's a good choice if your raised bed gets afternoon sun but not full sun all day.
These greens also don't attract onion pests like thrips or onion flies. They're ready to eat in 30 to 50 days depending on variety and season, so you get a second harvest from the same bed without replanting. Plant a new round of greens every two weeks if you want continuous harvests throughout the growing season.
Herbs that repel pests and save space
Dill, parsley, chives, and cilantro are the best herb companions for onions. Dill and cilantro repel onion flies and some aphids — pests that can damage onion foliage and bulbs. Parsley and chives take up almost no space and are perennial or self-seeding, so they come back year after year. Plant them at the edges of the bed or between onion clusters.
Chives are especially useful because they're a perennial allium (the same plant family as onions), so they grow in the same conditions and actually improve the soil structure around onions. Dill grows tall — 2 to 3 feet — so plant it on the north side of the bed so it doesn't shade shorter onions. All four herbs are edible and ready to harvest within weeks of planting. Once established, chives will come back every year and spread slowly, creating a permanent border.
Flowers that draw pests away from onions
Marigolds and nasturtiums are trap crops — they attract pests that would otherwise eat your onions. Marigolds draw spider mites and some aphids; nasturtiums attract aphids and whiteflies. Plant them around the edges of your raised bed, and they'll take the pest pressure off the center where your onions are. Both are edible flowers, so you're not wasting space.
Borage is another option if you have room. It attracts pollinators and repels some beetles, and the flowers are edible. Plant it on the north edge so it doesn't shade onions as it grows to 2 feet tall. All three flowers are straightforward to grow from seed and bloom throughout the season. The pests that land on the trap crops will feed there instead of moving to your onions, reducing damage to the bulbs and foliage.
Plants to keep away from onions
Avoid planting beans, peas, or other legumes directly beside onions. Onions release a compound that slows nitrogen fixation in legume roots, so beans and peas grow smaller and produce less. If you want legumes in the same bed, plant them at least 12 inches away or in a separate section of the raised bed.
Asparagus and onions also don't pair well — they attract similar pests and compete for the same nutrients. Garlic and onions are both alliums and can cross-pollinate if they flower, so keep them separated if you're saving seed. Otherwise, they grow fine together, but there's no benefit to planting them side by side. Potatoes should also stay separate because they need more frequent watering and deeper, richer soil than onions prefer.
Spacing and timing to make room for everything
The key to planting multiple crops in one raised bed is staggering them by maturity date. Plant fast-growing greens and radishes at the same time as onions, then pull them out 4 to 6 weeks later. Plant slower root crops like carrots and beets at the same time as onions and let them grow together to full size. Herbs and flowers can stay in the bed all season or year-round if you're in a mild climate.
Space onions 4 to 6 inches apart depending on the variety — smaller varieties like Egyptian walking onions can go closer. Give dill and nasturtiums 12 inches of space because they grow tall and wide. Lettuce, spinach, and parsley can go as close as 2 to 3 inches. Use a grid layout or mark rows with string to keep spacing even and make it straightforward to harvest without disturbing neighboring plants. This visual guide helps you see exactly where each plant goes and prevents overcrowding.
Frequently Asked Questions
Can I plant onions with tomatoes in the same raised bed?
Tomatoes and onions don't harm each other, but tomatoes need more space, deeper soil, and more frequent watering than onions do. If your raised bed is at least 12 inches deep and 3 feet wide, you can plant tomatoes on one end and onions on the other, keeping them 18 inches apart. Tomatoes will shade onions if they're too close, so give tomatoes the north side of the bed.
Do I need to separate onion varieties so they don't cross-pollinate?
Onions grown for bulbs won't cross-pollinate because you harvest them before they flower. Cross-pollination only matters if you're letting onions bolt and saving seed, which takes a full year. For eating onions, you can plant any varieties together without worry.
What if my raised bed is very small — can I still plant companions with onions?
Yes. Plant onions on a 6-inch spacing and add chives or parsley at the edges. Skip the tall herbs like dill and the sprawling flowers. Lettuce and spinach are good choices because they mature and come out before onions need more room. A 2-by-4-foot bed can hold 12 onions plus a border of herbs and greens.
Will planting herbs with onions change the flavor of the onions?
No. Flavor comes from the soil, water, and variety, not from nearby plants. Herbs and onions won't exchange flavors or affect each other's taste, even when grown side by side.
Can I plant onions with garlic in the same raised bed?
Yes, garlic and onions grow well together. Both are alliums, both need similar spacing and soil conditions, and neither harms the other. Plant them on the same 4- to 6-inch spacing. The only reason to separate them is if you're saving seed from both — otherwise, they're compatible neighbors.