A Seedling Spacing Chart You Can Print and Keep

Why do printed seedling spacing charts rarely help as much as they should? Most are just a flat list of inches, with no context for how to actually use the numbers. A chart is only as useful as your ability to turn its inches into an actual plant count for the bed in front of you. This article gives you both: the standard numbers, and the quick math to apply them to any bed.

Why Isn't Transplant Spacing the Same as Seed Spacing?

Seed packets often list a seed-sowing distance meant for a crop you'll thin later (sow every 2 inches, thin to every 4). Transplant spacing skips that step entirely, since a seedling already represents the "thinned" survivor. When you're moving seedlings from trays into a bed, use the transplant spacing number directly — don't also apply a thinning-buffer reduction, since there's nothing left to thin.

The Chart, Grouped by Spacing Range

Tight spacing (4-6 inches): lettuce (6-10 in.), spinach (4-6 in.), green onions (2-4 in.), radishes (2-3 in., though usually direct-sown), beets (3-4 in.).

Medium spacing (8-14 inches): Swiss chard (8-12 in.), kale (12-18 in.), broccoli (14-18 in.), cabbage (12-18 in.), bush beans (4-6 in. in-row, wider between rows), basil (10-12 in.).

Wide spacing (18-36 inches): tomatoes (18-36 in. depending on staking method), peppers (12-18 in.), eggplant (18-24 in.), squash (24-36 in.), cucumbers on a trellis (12-18 in.), melons (36-48 in.), pumpkins (48-72 in.).

Turning the Chart Into a Plant Count

Once you have a spacing number, the plant-count formula is: Plants = bed area ÷ (spacing in feet)², treating each plant as needing a square footprint equal to its spacing distance. For kale at 15 inches (1.25 feet) spacing in a 32-square-foot (4x8) bed: 1.25 × 1.25 = 1.56 square feet per plant, so 32 ÷ 1.56 = about 20 plants.

Compare that to tomatoes at 30 inches (2.5 feet) spacing in the same bed: 2.5 × 2.5 = 6.25 square feet per plant, so 32 ÷ 6.25 = about 5 plants. The same bed swings from 20 plants to 5 depending purely on which crop's spacing number you're using — which is exactly why a generic chart needs this second calculation step to be genuinely useful.

Root Ball Size: The Number the Chart Doesn't Show

Standard spacing charts assume a typical root ball size for seedlings started in standard cell trays (usually 72-cell or 128-cell flats, producing root balls under 2 inches across). If you've grown your seedlings in larger pots — 4-inch pots for tomatoes, for instance — the root ball itself can be 3 to 4 inches wide at transplant time, which eats into your smallest spacing margins. For tight-spacing crops like green onions at 2-4 inches, a root ball anywhere near that size effectively removes your safety margin; for wide-spacing crops like tomatoes, a few extra inches of root ball is a rounding error.

Adjusting the Chart for Succession Plantings

If you're transplanting several batches of the same crop through a season (lettuce every two weeks, for example), keep the spacing number constant across batches but track total plants used against your seed inventory separately. It's easy to plant the correct spacing per batch while still losing track of whether four batches of 20 lettuce seedlings each has exceeded the 80 seedlings you actually started — a seed-inventory problem, not a spacing problem, but one this chart alone won't catch.

Printing and Reusing the Chart

The most useful version of this chart isn't the generic inches-apart list above — it's that same list with a third column added for your specific bed's plant count, recalculated for each crop using the formula above. Once you fill that column in for your actual beds, the chart becomes a planting day reference instead of just general knowledge.

Bottom line: a seedling spacing chart is most useful as a starting input, not a finished plan. Take the inches-apart number for your crop, run it through the area-divided-by-spacing-squared formula against your actual bed size, and you'll have an exact plant count instead of a vague range — which is what actually determines how many seedlings to start in the first place.