Plan your garden beds with precision. Select a plant type or enter custom spacing to calculate exactly how many seeds or transplants you need, see a visual layout, and reference recommended spacing for popular vegetables, herbs, and flowers.
Seed Spacing Calculator
Layout Details
Visual Grid Preview
Each dot = 1 plantSeed Spacing Reference Chart
Click any row to load its spacing into the calculator. Spacing values are general guidelines -- always check your seed packet for variety-specific recommendations.
| Plant | Plant Spacing | Row Spacing | Planting Depth | Days to Harvest | Sun |
|---|
How Seed Spacing Is Calculated
The Formula
The calculator uses a simple row-and-column grid approach:
- Usable length = Bed length - (2 x edge buffer)
- Usable width = Bed width - (2 x edge buffer)
- Number of rows = floor(usable width / row spacing) + 1
- Plants per row = floor(usable length / plant spacing) + 1
- Base plants = rows x plants per row
- Total seeds = base plants + extra percentage buffer
Worked Example
Garden bed: 8 ft x 4 ft. Plant: Tomato (24" plant spacing, 36" row spacing). Edge buffer: 3 inches. Extra seeds: 10%.
- Usable length: 96" - 6" = 90 inches
- Usable width: 48" - 6" = 42 inches
- Rows: floor(42 / 36) + 1 = 2 rows
- Plants per row: floor(90 / 24) + 1 = 4 plants
- Base plants: 2 x 4 = 8
- With 10% extra: ceil(8 x 1.1) = 9 seeds
Why Edge Buffer Matters
An edge buffer keeps plants away from the bed walls. This prevents root competition with the bed frame, improves air circulation, and makes harvesting easier. A buffer of 3 to 6 inches works well for most plants.
Spacing Tips
- Intensive planting: In raised beds with rich soil, you can often reduce row spacing by 20-30% compared to in-ground rows.
- Succession planting: For crops like lettuce and radishes, plant a new batch every 2-3 weeks to extend your harvest.
- Companion planting: Alternate rows of compatible plants (e.g., tomatoes and basil) to maximize space and deter pests.
- Vertical crops: Cucumbers, beans, and peas can be grown on trellises with tighter row spacing.
About This Seed Spacing Calculator
This calculator helps home gardeners, raised-bed growers, and small-scale farmers plan their planting layout with precision. Instead of guessing how many seed packets to buy or how many transplants to prepare, enter your bed dimensions and plant type to get an exact count.
The visual grid preview shows where each plant will go in your bed, making it easy to mark your rows before planting. The reference table covers the most popular vegetables, herbs, and flowers with recommended spacing, planting depth, and days to harvest.
All calculations run in your browser. No data is collected or sent anywhere. Results update instantly as you adjust inputs.
Seed Spacing FAQ
How far apart should I plant tomatoes?
Tomatoes need 24 inches (60 cm) between plants and 36 inches (90 cm) between rows. Indeterminate (vining) varieties may need even more space. Proper spacing ensures good air circulation, which reduces disease risk like blight and powdery mildew.
How many plants fit in a 4x8 raised bed?
It depends on the plant type. Lettuce at 8-inch spacing fits about 48 plants. Tomatoes at 24-inch spacing fit about 8 plants. Carrots at 3-inch spacing fit over 200. Use this calculator with your specific plant and bed dimensions for an exact count.
What is the difference between row spacing and plant spacing?
Plant spacing is the distance between individual plants within the same row. Row spacing is the distance between parallel rows. Row spacing is typically wider to allow for walking, weeding, and harvesting. In raised beds, row spacing can be tighter since you access from the sides.
Should I add extra seeds?
Yes. Most gardeners add 10-20% extra seeds to account for poor germination, pest damage, and seedling loss. For direct-sow crops like carrots and radishes, sow generously and thin seedlings once they sprout. This calculator lets you adjust the extra percentage.
Can I use closer spacing in raised beds?
Often yes. Raised beds with high-quality soil and good drainage support intensive planting. You can reduce row spacing by 20-30% compared to traditional in-ground rows. However, do not reduce plant spacing within rows -- each plant still needs room to grow.
What is square foot gardening spacing?
Square foot gardening divides beds into 1-foot squares and plants a specific number per square based on plant size. For example: 1 tomato per square, 4 lettuce per square, 16 radishes per square. This calculator uses traditional row spacing, but you can compare results with SFG guidelines.
How deep should I plant seeds?
A general rule is to plant seeds 2-3 times their diameter deep. Tiny seeds like lettuce and carrots go just 1/4 inch deep. Large seeds like beans and corn go 1-2 inches deep. Select a plant preset above to see specific depth recommendations.
Does this calculator work for flower beds?
Yes. Enter your flower bed dimensions and the spacing recommended on the plant tag or seed packet. The calculator works for any plant type -- vegetables, herbs, flowers, or ground covers.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are estimates and may vary based on actual conditions.
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Seed Spacing Calculator FAQ
How far apart should I plant tomatoes?
Tomatoes need 24 inches (60 cm) between plants and 36 inches (90 cm) between rows. Indeterminate varieties may need even more space. Proper spacing ensures good air circulation, which reduces disease.
How many plants fit in a 4x8 raised bed?
It depends on the plant type. For example, lettuce at 8-inch spacing fits about 48 plants, while tomatoes at 24-inch spacing fit about 6 plants. Use this calculator to get exact counts for any plant type.
What is the difference between row spacing and plant spacing?
Plant spacing is the distance between individual plants within the same row. Row spacing is the distance between parallel rows. Row spacing is typically wider to allow for walking, weeding, and harvesting access.
Should I add extra seeds when planting?
Yes. Most gardeners plant 10-20% more seeds than needed to account for germination failure. For direct-sow crops like carrots and lettuce, sow extra and thin seedlings to proper spacing after they emerge.