Plant Spacing Calculator
Count how many plants fit in a rectangular bed at a given spacing on a square or triangular grid, with the area each plant gets.
Common Plant Spacing
Updated Formula covered by automated tests
Seed packets give a spacing such as “thin to 12 inches apart”, but they do not tell you how many transplants to buy for a 4 by 10 ft raised bed. This calculator lays plants out on a grid inside your bed and counts them, so you know how many seedlings to start, how many plants a nursery flat will cover, and how much room each plant gets.
Every plant is kept at least half a spacing from the bed edge, so the plants along the border get the same root and leaf room as those in the middle and do not hang over the path. You can choose a square grid, where plants line up in both directions, or a triangular pattern with alternate rows shifted, which is how many intensive gardeners plant greens and roots.
The formula
- L
- Bed length in feet, the direction the rows run
- W
- Bed width in feet
- s
- Plant spacing (center to center) converted from inches to feet
- ⌊ ⌋
- Round down, because a partial plant does not fit
- s × √3 ÷ 2
- Distance between rows in a triangular pattern, about 0.866 of the spacing, which keeps every plant exactly s from its neighbors
Along a row, the first plant sits s ÷ 2 from the end and each further plant is s farther on, so the number that fit is the usable run (L − s) divided by s, rounded down, plus the first plant. Rows across the bed are counted the same way. The total for a square grid is plants per row times rows.
In a triangular layout each plant is the corner of an equilateral triangle, so rows can sit closer together (0.866 s instead of s) while every plant stays one full spacing from its neighbors. Alternate rows are shifted half a spacing and may hold one plant fewer. In long, wide beds that packs in roughly 10 to 15 percent more plants; in narrow beds with wide spacing the extra row may not fit and the gain disappears.
Worked example
Ana has a 4 by 10 ft raised bed and wants to fill it with bell peppers at the 18 inch spacing printed on the seed packet, in a square grid.
- 1 Convert the spacing: 18 ÷ 12 = 1.5 ft.
- 2 Plants per row along the 10 ft side: (10 − 1.5) ÷ 1.5 = 5.67, round down to 5, plus 1 = 6 plants.
- 3 Rows across the 4 ft side: (4 − 1.5) ÷ 1.5 = 1.67, round down to 1, plus 1 = 2 rows.
- 4 Total: 6 × 2 = 12 plants, each with 40 ÷ 12 = 3.33 sq ft of bed.
Result: Ana should buy or start 12 pepper plants, plus a couple of spares in case some fail to establish.
Before you rely on the result
- Assumes a rectangular bed and one crop at one spacing. For mixed plantings, run each section separately.
- Spacing guidance varies by variety: a dwarf patio tomato and a sprawling heirloom need very different room, so the seed packet or plant tag should set the spacing you enter.
- Vining crops such as squash and cucumbers may be grown on a trellis at closer spacing than the ground-level figures here suggest.
Frequently asked questions
What spacing should I use: the in-row distance or the between-row distance on the packet?
Packets written for long single rows list a tight in-row spacing and a wide between-row spacing meant for walking and hoeing. In a raised or intensive bed where you never step, use the in-row figure in both directions. The common plant buttons here use typical in-bed spacings.
How does this compare with square foot gardening?
Square foot gardening, popularized by Mel Bartholomew, divides a bed into 1 ft squares and puts 1, 4, 9 or 16 plants in each, which equals spacings of 12, 6, 4 and 3 inches. Enter those spacings with a square grid and you get the same counts, for example 32 plants at 12 inches in a 4 by 8 ft bed.
Can I plant closer than the packet says?
A little, in rich, well-watered soil, and many gardeners do. But crowded plants compete for light, water and nutrients, stay smaller, and dry out more slowly after rain, which encourages leaf diseases. For tomatoes, squash and other large plants, generous spacing usually yields more than an extra plant would.
Sources
- University of Minnesota Extension: Yard and garden (extension.umn.edu)