Companion Planting Onions and Garlic: A Step-by-Step Guide for Beginners

By Emily Parker

Updated November 2026

Companion planting onions and garlic is one of the simplest ways to make a vegetable bed work harder. Done well, you get tighter spacing, fewer aphids and thrips, and a crop rotation that keeps soil diseases from building up. This guide walks through the pairings that work, the ones that don’t, and a practical layout you can copy into a raised bed or in-ground row this season.

Why Onions and Garlic Make Good Companions

Onions and garlic belong to the Allium family, and their strong sulfur compounds are the reason they show up in so many companion planting lists. Many gardeners report that aphids, carrot rust fly and some beetles are less likely to settle near alliums, though the evidence is mostly anecdotal and works best as a supplement to good monitoring rather than a replacement for it. The bigger practical benefit is space efficiency: alliums are narrow, upright and fairly quick to harvest in the case of green onions, which lets you fill gaps between slower crops.

Shopping for one? See our guide: 6 Best Onions and Potatoes Companion Planting Books and Guides for 2026.

Alliums also have shallow, fibrous roots that don’t compete much with deeper-rooted neighbors, so they pair well with crops that need a bit more depth. Keep in mind that the reverse is also true: alliums do best when they aren’t crowded by heavy feeders or thick-leaved plants that shade them.

Choosing the Right Partners for Alliums

The best pairings for onions and garlic are crops with different root depths, different nutrient needs and different pest profiles. The table below summarizes the most commonly recommended partners and the reason each one works.

For more specific pairings, see Companion Planting for Onion: 8 Best Pairings and What to Avoid and Companion Planting for Garlic: 7 Best Partners and Pitfalls (2026). If you are working with a potato patch, Garlic and Potatoes Companion Planting: A Step-by-Step Guide for Better Yields covers timing and spacing in detail.

Crops to Keep Away From Alliums

Several common vegetables do poorly near onions and garlic, mostly because they are heavy feeders or prefer a different growing environment. Beans and peas are the most frequently cited problem partners, since the nitrogen they fix doesn’t benefit alliums and the dense foliage can shade them. Asparagus and sage are also usually kept apart. If you are unsure, Companion Planting for Onion: 8 Best Pairings and What to Avoid has a fuller list of crops to separate.

Step-by-Step: Planting an Onion and Garlic Companion Bed

A good companion bed starts with preparation, not just placement. Use the steps below for either a raised bed or an in-ground row.

Step 1: Prepare the Soil

Alliums want loose, well-drained soil with a pH between 6.0 and 7.0. Work in 2 to 3 inches of finished compost to a depth of about 8 inches. Heavy clay should be amended more aggressively, and raised beds usually need only a light top-up. Avoid fresh manure close to planting, since it can cause rot in bulbs.

Step 2: Set Your Layout

Plant alliums in rows 12 inches apart, and place your companions in the gaps or in separate rows. A common approach is to alternate one row of onions with one row of carrots or lettuce. In a raised bed, a grid of 4 by 4 inch spacing for onions works well, with lettuce or radishes tucked between them. If you want a visual plan before you start, the Raised Bed Garden Layout Companion Planting: A Step-by-Step Guide walks through block layouts.

Step 3: Time Your Planting

Garlic is planted in fall, usually 4 to 6 weeks before the ground freezes, and is harvested the following summer. Onion timing depends on the type: short-day onions go in during late winter in the South, while long-day onions are set out in early spring in the North. Lettuce and beets can share the bed in early spring and be harvested before the alliums need the space.

Step 4: Plant and Water

Set garlic cloves pointed end up, 2 inches deep and 4 to 6 inches apart. Onion sets go 1 inch deep, spaced 3 to 4 inches apart. Water deeply after planting, then keep the bed evenly moist but not soggy. Overwatering is the most common cause of rot.

Step 5: Monitor and Maintain

Check the bed weekly for thrips, which cause silvery streaks on onion leaves, and for aphids on the companions. Hand-pick pests when you see them, and keep the bed weeded, since alliums are poor competitors. Stop watering garlic two to three weeks before harvest, and let onions cure in a dry, shaded spot after pulling.

Practical Checklist Before You Plant

1. Test or estimate soil pH and aim for 6.0 to 7.0.
2. Amend with 2 to 3 inches of compost worked in to about 8 inches deep.
3. Choose onion type (short-day or long-day) based on your region.
4. Sketch a layout with row spacing of 12 inches for alliums.
5. Pick companions with different root depths and clear spacing requirements.
6. Source disease-free garlic bulbs or onion sets from a reputable seller.
7. Mulch lightly after planting to keep moisture even.

Common Mistakes to Avoid

• Crowding the bulbs. Companion crops that fill the gaps too early can shade alliums and reduce bulb size.
• Planting alliums where other alliums grew last year. Rotate them to a new bed every 3 to 4 years to limit white rot and onion maggot.
• Overwatering near harvest. Wet soil late in the season invites rot and reduces storage life.
• Assuming companions solve every pest. Companion planting helps at the margins; regular scouting still matters most.
• Using fresh manure. It can burn roots and promote disease in bulbs.

Tips for Better Results

Plant a few extra garlic cloves in a separate spot so you have seed stock for next year. Pull green onions early to thin the row and give the remaining bulbs more room. Keep a simple garden journal noting planting dates and pest sightings; after one season you will know which pairings actually perform in your soil. For a broader look at planning, see Vegetable Gardening Companion Planting: A Step-by-Step Guide for Beginners.

FAQ

Can I plant garlic and onions together?

Yes, but they are the same family and compete for the same nutrients and pests. Many gardeners prefer to separate them into different beds or rotate them yearly to reduce disease buildup.

What vegetables grow well next to onions and garlic?

Carrots, lettuce, beets, strawberries and tomatoes are commonly recommended partners. Each works because it has a different root depth or pest profile from the alliums.

What should I not plant near garlic?

Beans, peas, asparagus and sage are usually kept apart because they compete for space or have different growing needs. Shading from tall or dense plants is also a concern.

How far apart should onions and garlic be planted?

Garlic cloves go 4 to 6 inches apart, and onion sets go 3 to 4 inches apart, in rows about 12 inches apart. Adjust for bulb size goals; wider spacing yields larger bulbs.

Do onions and garlic repel pests?

Many gardeners report fewer aphids and carrot rust flies near alliums, but results vary. Treat this as one supporting tool alongside monitoring and hand-picking.

When should I plant garlic for companion beds?

Plant garlic in fall, about 4 to 6 weeks before the ground freezes. It will overwinter and be harvested the following summer.

Can I grow onions and garlic in containers together?

Yes, a container at least 12 inches deep works for both. Keep them in full sun and water consistently, since containers dry out faster than beds.

Conclusion

Companion planting onions and garlic works best when you pick partners with different root depths and pest profiles, space the rows properly, and keep the bed weeded and evenly watered. Start with one or two pairings this season and track what happens. Over a few years, you will build a layout tuned to your own soil and climate.

About Emily Parker

Emily Parker is part of our editorial team and reviews and edits our vegetable & edible gardening guides, checking product details against manufacturer specifications and owner feedback.