Planning out your garden or allotment beds is a good way to get the most out of the natural benefits of planting certain types of plants close to each other. In this way, you can keep pests away, get helpful pollinators, and maybe even make your vegetables taste better when they’re ready to be picked.
Onions are a versatile vegetable to grow and pairing them with companion plants can enhance their growth and flavor. The right onion companion plants deter pests attract pollinators, and provide nutrients or shade. Follow this guide to the top plants for companion planting with onions.
Why Grow Onion Companion Plants?
Companion planting is the practice of strategically planting crop species together so they can benefit each other. Reasons for pairing onions with certain plants include:
- Repelling insect pests like carrot flies, onion flies, and cabbage moths
- Providing shade and mulch to retain moisture
- Fixing nitrogen and accumulating nutrients to improve soil health
- Attracting beneficial pollinators
- Enhancing growth and flavor
Combining onions with compatible companions makes for a healthy thriving garden ecosystem.
Best Onion Companion Plants
Here are some of the best options for companion planting with onions:
1. Lettuce
Some lettuce varieties can be grown as cover crops around onions The shade helps retain moisture while lettuce quickly matures and fills space efficiently.
2. Carrots
Carrots and onions have different root depths so they don’t compete for nutrients. Planting together can confuse pests like carrot flies.
3. Dill
Dill attracts beneficial insects that prey on pests damaging to onions. It also enhances onion flavor.
4. Brassicas
Broccoli, kale, cabbage, and other brassicas repel onion pests. Their edible leaves make good nutrient accumulators.
5. Radishes
Radishes loosen compacted soil and make a quick cover crop for onions. Their fast growth is great for succession planting.
6. Beets
Beets improve soil structure and moisture retention. They share ideal growing conditions with onions.
7. Chamomile
The small edible flowers of chamomile deter onion pests like aphids. Chamomile also attracts pollinators.
8. Marigolds
Marigolds heavily repel pests like nematodes, onion flies, and aphids. The bright blooms also attract pollinators.
9. Basil
Basil repels pests like mosquitos, flies, and aphids. It also enhances onion flavor when planted nearby.
10. Rosemary
The aromatic woody herb rosemary naturally deters insects and provides dappled shade ideal for onions.
11. Thyme
Low-growing thyme acts as a living mulch, suppressing weeds and retaining moisture for onions.
12. Rue
Rue’s strong scent masks the onion fragrance, protecting them from onion flies and other pests drawn to onion plants.
13. Hot Peppers
Peppers attract beneficial wasps that control beetles, flies, and other onion pests.
14. Celery
Celery repels onion pests with its aroma. Its shallow roots don’t compete with onion bulbs.
15. Summer Savory
Savory is said to improve the flavor of nearby onions, reducing their pungency and increasing sweetness.
16. Swiss Chard
Swiss chard provides shade to keep the soil moist. Its roots don’t compete with onions for space and nutrients.
17. Spinach
Onions help protect spinach from pests like rabbits and insects. Both benefit from enriched soil.
18. Garlic and Other Alliums
Onions pair well with garlic, leeks, shallots, and chives. But be mindful of shared diseases.
What Not to Plant with Onions
Some plants should be avoided when companion planting with onions:
- Asparagus – Competes with onions for space and nutrients
- Turnips – Also compete for space in the garden
- Peas – Have similar nutrient needs as onions
- Beans – May imbalance soil nitrogen levels
- Sage – Produces compounds that inhibit onion growth
- Garlic – Risk of spreading diseases and pests
Tips for Planting Onion Companions
- Amend soil with compost and organic matter before planting
- Consider crop rotation from year to year
- Provide plenty of sun and air circulation
- Use trellising or cages to control vining crops
- Pay attention to mature plant sizes to allow adequate space
- Time plantings so companions mature simultaneously
- Mix up companion plants between rows and interplant quick crops
Combining onions with beneficial companion plants results in a diverse, thriving vegetable garden. With a bit of planning, these plant pairings can support each other and your harvest.
What grows well with onions?
Onions are a great plant to grow next to other plants because their strong smell keeps pests away. Bugs like aphids and bigger animals like rabbits will stay away from your garden if it smells like onions.
Plants that can be helped along by proximity to onions include:
- Brassicas: Onions keep cabbage worms, loopers, and maggots away. Along with cabbage, you can choose from broccoli, kale, cauliflower, turnips, brussel sprouts, and more.
- Carrots – Onions have a repellent effect on carrot fly.
- Beets: Onions can help protect your beets from aphids, sugar beet-flea beetles, rabbits, and deer because they are naturally poisonous.
Other crops can also help onions if they are planted close to them. They can improve the growing conditions, the flavor, and their ability to keep pests away. These include:
You should also think about other plant combinations that don’t help each other directly but can be useful in other ways. For example, lettuce doesn’t help onions much, and onions don’t help lettuce much either, except that their roots are at different depths. So, your lettuce won’t have to compete with your onions for nutrients. You can plant them closer together to make the most of the space in your garden.
Planting Onion Sets: What to Watch Out For
FAQ
Can peppers and onions be planted together?
Can you plant onions and tomatoes together?
What should you not plant after onions?