Why Spacing Matters
Plant spacing affects three things:
- Competition – plants too close together compete for light, water, and nutrients, reducing yield and increasing disease risk
- Airflow – adequate spacing reduces humidity around foliage, reducing fungal disease
- Yield per area – too much space wastes productive ground; too little reduces individual plant performance
Getting spacing right is a balance between yield per plant and number of plants per square metre.
Two Approaches: Row vs Square Foot Gardening
Traditional row gardening: Plants are arranged in rows with wide paths between them. Spacing is stated as "30 cm between plants, 60 cm between rows." This was designed for mechanized cultivation; the wide paths allow a tractor or rototiller through.
Square foot / raised bed gardening: Plants are arranged in a grid within a dense raised bed. Spacing equals the grid square size. More intensive, higher yield per area, but requires better soil fertility and water management. No room for machines.
Both are valid; raised beds suit most home gardens.
Recommended Spacing for Common Vegetables
Vegetables with Tight Spacing (15–20 cm grid / row)
| Plant | Grid spacing | Row spacing |
|---|---|---|
| Radishes | 5 cm | 15 cm |
| Spring onions | 5–10 cm | 15 cm |
| Lettuce (cut-and-come-again) | 15 cm | 15 cm |
| Spinach | 15 cm | 30 cm |
| Beets / Beetroot | 10 cm | 30 cm |
Medium Spacing (30–45 cm)
| Plant | Grid spacing | Row spacing |
|---|---|---|
| Carrots | 7–10 cm | 30 cm |
| Onion bulbs | 10 cm | 25 cm |
| Garlic | 15 cm | 30 cm |
| Bush beans (French beans) | 15 cm | 45 cm |
| Peas | 10 cm | 60 cm |
| Lettuce (heads) | 30 cm | 30 cm |
| Kale | 45 cm | 60 cm |
| Broccoli | 45 cm | 60 cm |
Large Spacing (60+ cm)
| Plant | Grid spacing | Row spacing |
|---|---|---|
| Tomatoes (bush) | 60 cm | 75 cm |
| Tomatoes (indeterminate/cordon) | 50 cm | 90 cm |
| Courgettes / Zucchini | 90 cm | 90 cm |
| Cucumbers | 45 cm | 90 cm |
| Sweetcorn | 30 cm grid (blocks only) | – |
| Squash / Pumpkins | 90–120 cm | 120 cm |
| Brussels sprouts | 60 cm | 75 cm |
| Cauliflower | 60 cm | 75 cm |
How to Calculate Plant Count for a Bed
For a rectangular bed, calculating how many plants fit in a grid is straightforward:
Number of plants = (Bed length / spacing) × (Bed width / spacing)
Example: A 2 m × 1.2 m bed planted with lettuce at 30 cm spacing:
- Along length: 200 cm ÷ 30 cm = 6 plants
- Along width: 120 cm ÷ 30 cm = 4 plants
- Total: 6 × 4 = 24 lettuce plants
For circular or irregular beds, calculate the area in cm² and divide by the area per plant (spacing²):
Plants = Bed area (cm²) / (spacing cm)²
Interplanting and Companion Planting
You can increase effective yield by planting complementary crops in the same space:
- Three Sisters – sweetcorn, beans, squash planted together (beans climb the corn, squash shades the ground)
- Lettuce under tall brassicas – lettuce tolerates partial shade; tuck it under broccoli or Brussels sprouts
- Radishes as trap crops – fast-maturing radishes between slower crops; harvest before they compete
Plant Spacing Calculator
The Plant Spacing Calculator on this site calculates how many plants fit in a bed of any size for a given spacing – enter bed dimensions and spacing, get plant count instantly.
Summary
Correct plant spacing prevents competition and disease while maximising yield per area. Traditional row spacing is wider than necessary for home gardens; raised bed / square-foot spacing is more intensive and productive. Calculate plant count by dividing bed dimensions by plant spacing in both directions. When in doubt, err on the side of slightly more space – overcrowded plants underperform significantly.