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Seed Spacing Calculator

Calculate optimal plant spacing and garden capacity

Common Spacing (inches)

Tomatoes:24" × 36"
Lettuce:6" × 12"
Carrots:2" × 6"
Peppers:18" × 24"
Beans:4" × 18"
Corn:8" × 30"
Squash:36" × 48"
Onions:4" × 12"
Spinach:4" × 12"
Radishes:1" × 6"

Spacing Tips

  • • Consider mature plant size when spacing
  • • Account for air circulation to prevent disease
  • • Plan for harvest accessibility between rows
  • • Follow seed packet recommendations as guidelines
  • • Adjust spacing based on growing conditions and climate

Seed Spacing Calculator Guide

Convert row and in-row spacing into plant counts per bed or row, so you buy the right amount of seed and avoid overcrowding. Supports imperial and metric units and common garden layouts.

What is Plant Spacing?

This tool helps home gardeners and market growers set in-row spacing (distance between plants in a row) and between-row spacing, then converts bed dimensions into plant counts and seeding rates.

How to Use This Tool

  1. Select layout: rows on a bed, single row, or grid.
  2. Enter bed/row dimensions (length and width).
  3. Enter spacing: in-row spacing (plant to plant) and between rows.
  4. Choose units (in/cm) and waste factor for thinning.
  5. Calculate plant count, rows per bed, and seeds to buy (with a buffer).

Formulas & Methods

  • Plants per row: N_row = floor(L / S_inrow) where L is row length and S_inrow is in-row spacing.
  • Rows per bed: R = floor(W / S_row) for bed width W and row spacing S_row.
  • Total plants (row layout): N_total = N_row * R.
  • Grid layout: N_total = floor(L / S_inrow) * floor(W / S_row).
  • Seed quantity: Seed_needed = N_total * (1 + buffer%) to cover germination and thinning.
  • Square-foot gardening: convert to per-1 ft^2 density (e.g., 16 radishes per square at 3 in spacing).

Assumptions & limitations

  • Spacing is variety- and climate-specific; consult seed packet guidance.
  • For transplants, survival rates vary; add a buffer for losses.
  • Intensive systems (e.g., biointensive) can push closer spacing but need rich soil and frequent harvests.

Examples

Example A — Lettuce heads
Bed 20 ft long, 3 ft wide. In-row 12 in, row spacing 12 in.
Rows per bed = floor(36/12) = 3. Plants per row = floor(240/12) = 20.
Total = 60 plants. Add 10% buffer -> order 66 plugs/seeds.

Example B — Carrots (dense sow)
Row 16 ft; in-row 2 in; rows = 4 on a 2 ft bed (6 in between).
Plants/row = floor(192/2) = 96; total = 384. Add 20% extra for thinning -> sow for ~460 seedlings.

| Crop | In-row | Row spacing | Plants in 20x3 ft bed | |---|---|---|---:| | Lettuce (head) | 12 in | 12 in | 60 | | Kale | 18 in | 18 in | 40 | | Radish | 3 in | 3 in | 256 |

Pro Tips & Best Practices

  • Thin early to target spacing for uniform size and airflow.
  • Stagger rows (triangular grid) to increase density slightly while keeping airflow.
  • Leave paths between beds to prevent compaction.
  • Add mulch or drip lines to reduce weeds and improve water efficiency.
  • Keep a log of spacing vs yield to refine next season.

Related Calculators

FAQ

Q: How far apart should I plant seeds?

A: Spacing depends on the plant. Use two distances: in-row spacing (between plants) and between-row spacing to avoid overcrowding.

Q: How do I estimate plant count for a bed?

A: Plant count = (bed length / in-row spacing) * (bed width / row spacing) for a grid; subtract a small edge margin.

Q: Does thinning change spacing?

A: Yes—sow slightly denser and thin to the target spacing to ensure a full stand.

Q: How does variety affect spacing?

A: Vigorous varieties and large fruiting plants need more space; dwarf or cut-and-come-again types need less.

Q: Should I use square-foot gardening?

A: Yes, for small beds. Convert row spacing into per-square recommendations to simplify planning.

Call to Action

Enter your bed size and desired spacing to get plant counts and seed needs—avoid crowding and harvest more uniform produce.