Companion Planting: Use This Spacing Chart for Success

Key Takeaways

• Understand the science behind companion planting and optimal spacing for plant health.
• Learn how precise spacing improves yield, pest control, and resource efficiency.
• Use our custom spacing chart to plan your garden layout mathematically.
• Discover common spacing mistakes and how to avoid them.

1. Introduction

Companion planting is a time-tested gardening technique that pairs plants to enhance growth, deter pests, and maximize space. But while many gardeners focus on which plants to pair, the secret to success lies in precise spacing. Proper spacing ensures plants share nutrients efficiently, reduce competition, and create a healthier ecosystem. In this guide, we’ll break down the math behind optimal spacing and provide a custom chart to help you plan your garden like a pro.

2. The Science of Spacing in Companion Planting

Root Systems and Nutrient Uptake

Plants with complementary root depths (e.g., shallow-rooted lettuce with deep-rooted carrots) thrive when spaced correctly. Too close, and they’ll compete for water and nutrients; too far, and you waste space. Research from the University of California shows tomato yields increase by 20% when spaced 18–24" apart, allowing roots to access nutrients without overlap.

Light and Airflow

Crowded plants block sunlight and trap moisture, inviting fungal diseases. For example, basil planted 12" from tomatoes improves airflow while repelling pests—but cramming them too close shades both plants.

Pest Management

Strategic spacing disrupts pest habitats. Onions interspersed with carrots (6" apart) mask carrot scent from root flies, while marigolds planted every 3 feet deter nematodes without overcrowding.

3. The Companion Planting Spacing Chart

How to Read the Chart

Adjust spacing based on your garden style:

• Rows: Leave 12–18" between rows for access.
• Square-foot gardening: Divide beds into 1-foot grids (e.g., 9 garlic plants per square).

Sample Pairings with Spacing

Companion Pair	Spacing
Tomatoes + Basil	18" between tomatoes, 12" for basil
Carrots + Onions	6" between rows, 3" within rows
Corn + Beans + Squash (Three Sisters)	Corn: 12–18", Beans: 6", Squash: 24–36"

4. Calculating Spacing for Your Garden

Step-by-Step Math

1. Measure your garden area (e.g., 4' × 8' raised bed = 32 sq ft).
2. Calculate plant density: For broccoli (1 plant/sq ft), you’d fit 32 plants.
3. Adjust for mature size: Zucchini needs 3+ feet—plant at bed edges.

Spacing Formulas

• Square-foot gardening: 1 plant per square for large plants (peppers), 4–9 for small (radishes).
• Traditional rows: Use the shoulder width rule: Space = mature width + 20% (e.g., cabbage spans 18", so plant 22" apart).

5. Common Spacing Mistakes and Fixes

• Overcrowding: Thin seedlings early—kale sprouts need 12", not 2".
• Underutilizing space: Plant fast-growing radishes between slow brassicas.
• Ignoring vertical space: Trellis cucumbers to save ground for shade-loving spinach.

6. Advanced Tips for Mathematical Garden Planning

• Succession planting: After harvesting garlic (6" spacing), replant with bush beans (4" spacing).
• Microclimate adjustments: In hot climates, place lettuce 8" apart (not 12") for shade.
• Tech tools: Apps like Planter auto-calculate spacing for companion pairs.

7. Conclusion

Companion planting isn’t just about what you grow—it’s about where and how close. Use our spacing chart as a starting point, then tweak based on your garden’s unique conditions. Ready to try? Download our printable guide or experiment with a garden planner tool to turn math into harvest!