Can You Grow Onions and Garlic Together? Complete Guide

Yes, you can grow onions and garlic together—they're compatible companion plants that share similar growing requirements, deter common pests, and maximize garden space efficiency. This guide reveals exactly how to plant them together for optimal harvests while avoiding common mistakes.

Many home gardeners wonder if they can grow onions and garlic together in their vegetable plots. The good news is that not only can you grow these allium family members side by side, but doing so offers multiple benefits for your garden ecosystem. As experienced gardeners have discovered through centuries of practice, these two crops make excellent companions when planted with proper spacing and timing.

Why Onions and Garlic Thrive as Garden Companions

Onions (Allium cepa) and garlic (Allium sativum) belong to the same plant family, sharing similar environmental preferences that make them natural companions. Both require:

• Full sun exposure (6-8 hours daily)
• Well-draining soil with pH between 6.0-7.5
• Moderate watering (1 inch per week)
• Cooler temperatures during bulb formation

According to research from the University of California Agriculture and Natural Resources, alliums like onions and garlic naturally repel many common garden pests including aphids, Japanese beetles, and carrot flies through their sulfur compounds. When planted together, they create a stronger protective barrier for neighboring plants.

Growing Requirement	Onions	Garlic
Optimal Soil pH	6.0-7.5	6.0-7.5
Water Needs	1 inch/week	1 inch/week
Planting Depth	1-2 inches	2-3 inches
Harvest Time	100-170 days	180-270 days

Step-by-Step Guide to Planting Onions and Garlic Together

1. Soil Preparation (4-6 Weeks Before Planting)

Prepare your garden bed by incorporating 2-3 inches of compost and a balanced organic fertilizer. The USDA Natural Resources Conservation Service recommends testing your soil pH and adjusting with lime (to raise pH) or sulfur (to lower pH) as needed to reach the optimal 6.0-7.5 range.

2. Timing Your Planting

Planting timing differs slightly between these alliums:

• Garlic: Plant cloves in fall (4-6 weeks before first frost) for largest bulbs
• Onions: Plant sets or transplants in early spring after soil reaches 50°F

If planting both in spring, start with onions first, then follow with garlic 2-3 weeks later to account for garlic's longer growing season.

3. Proper Spacing Configuration

Spacing is critical when growing onions and garlic together. Follow these guidelines:

• Leave 4-6 inches between individual plants
• Space rows 12-18 inches apart
• Plant garlic slightly deeper (2-3 inches) than onions (1-2 inches)
• Alternate plants in a checkerboard pattern for optimal space use

The Cornell University Gardeners' Handbook notes that proper spacing prevents competition for nutrients while maintaining the pest-repelling benefits of close planting.

Common Challenges and Solutions

While onions and garlic generally grow well together, watch for these potential issues:

Nutrient Competition

Both plants are moderate feeders that require nitrogen early in growth and phosphorus/potassium during bulb formation. Solution: Apply a balanced fertilizer when plants reach 6 inches tall, then switch to a low-nitrogen, high-phosphorus formula as bulbs begin forming.

Disease Management

Though they share some disease vulnerabilities, proper spacing and crop rotation minimize risks. The University of Minnesota Extension reports that rotating alliums to new locations every 3-4 years reduces soil-borne disease pressure by up to 70%.

Harvesting and Storage Timeline

Understanding the different maturity timelines prevents harvest mistakes:

• Green onions: Harvest 60-80 days after planting when tops reach 6-8 inches
• Garlic scapes: Cut when curling (about 2 months before bulb harvest)
• Garlic bulbs: Harvest when 1/3 of leaves turn brown (typically July)
• Dry onions: Harvest when tops fall over naturally (late summer)

Proper curing is essential for storage. The National Gardening Association recommends curing both crops in a warm, dry, well-ventilated area for 2-3 weeks before storing at 32-40°F with 60-70% humidity.

What NOT to Plant Near Your Onion-Garlic Combination

While onions and garlic grow well together, avoid planting them near:

• Beans and peas (inhibit growth)
• Lentils (compete for nutrients)
• Sage (stunts growth)

Instead, consider adding carrots between your allium rows—carrots actually grow better when planted near onions and garlic as the alliums repel carrot flies.

Seasonal Rotation Planning

After harvesting your onion-garlic combination, rotate to a different plant family. The Rodale Institute's Farming Systems Trial shows that proper crop rotation increases soil health by 30% and reduces pest pressure by 50% compared to continuous planting.

Excellent follow-up crops include:

• Legumes (beans, peas) to replenish nitrogen
• Brassicas (broccoli, cabbage) which benefit from residual sulfur
• Leafy greens (lettuce, spinach) that prefer similar soil conditions

Can onions and garlic be planted in the same garden bed?

Yes, onions and garlic can be planted together in the same garden bed. They share similar growing requirements and actually benefit each other by repelling common pests. Just maintain proper spacing of 4-6 inches between plants and alternate them in a checkerboard pattern for best results.

Do onions and garlic compete for nutrients when planted together?

Onions and garlic can compete for nutrients if planted too closely. To prevent competition, space plants 4-6 inches apart, apply balanced fertilizer when plants reach 6 inches tall, and switch to a low-nitrogen formula as bulbs begin forming. Proper spacing and targeted feeding eliminate most nutrient competition issues.

When should I plant onions and garlic together?

For best results, plant garlic cloves in fall (4-6 weeks before first frost) and onion sets in early spring after soil reaches 50°F. If planting both in spring, start with onions first, then follow with garlic 2-3 weeks later to account for garlic's longer growing season.

What spacing should I use for onions and garlic planted together?

Space individual plants 4-6 inches apart with rows 12-18 inches apart. Plant garlic slightly deeper (2-3 inches) than onions (1-2 inches). Alternate the plants in a checkerboard pattern rather than planting in separate rows to maximize space efficiency and pest-repelling benefits.

What should I plant after harvesting onions and garlic?

After harvesting onions and garlic, rotate to a different plant family. Excellent follow-up crops include legumes (beans, peas) to replenish nitrogen, brassicas (broccoli, cabbage) which benefit from residual sulfur, or leafy greens (lettuce, spinach) that prefer similar soil conditions. Avoid planting beans, peas, or sage near your alliums in the same season.