How far apart to plant sweet corn
Virginia Cooperative Extension and Utah State University Extension space sweet corn 6 to 12 inches apart in the row, with rows 24 to 36 inches apart. In a raised bed, about 15 inches each way works, and University of Wisconsin Extension's square foot guide fits 2 plants per square foot. The calculator starts on the 15 inch bed spacing.
Spacing is only half of it with corn. How you arrange the plants decides whether the ears fill.
Plant corn in a block, not a single row
Corn is wind pollinated: pollen from the tassels at the top has to land on the silks of the ears below. Utah State recommends planting a block of at least three or four short rows rather than one long row, so pollen falls on neighboring plants whichever way the wind blows. The block is what gives well-filled ears.
With Rows selected, the calculator uses 9 inches in the row and 30 inches between rows. Four rows 10 feet long hold 13 plants each, 52 in all, in a block 10 feet long with 7.5 feet from the first row to the last. That gives better pollination than the same 52 plants in a 40 ft row.
How many corn plants fit a raised bed
| Bed | 15 in each way | Rows, 9 × 30 in | Square foot method (2 per sq ft) |
|---|---|---|---|
| 4 × 4 ft | 9 | 5 | 32 |
| 4 × 8 ft | 18 | 10 | 64 |
| 3 × 6 ft | 8 | 8 | 36 |
| 4 × 12 ft | 27 | 16 | 96 |
The first two columns keep half a spacing clear along the bed edges, the way the calculator counts. The square foot count is the densest option; a 4 × 8 bed at 15 inches gives 18 plants arranged in 3 rows, which is already a small block.
Corn row spacing
The 24 to 36 inch row spacing is for in-ground rows you walk between. A 25 ft row at 9 inches holds 33 plants.
Keep sweet corn types apart
Standard (su), sugary enhanced (se) and supersweet (sh2) corn cross-pollinate. Utah State advises keeping them from tasseling at the same time, for example by sowing them at different dates, or the sweeter types lose their sweetness.
Depth, timing and seed
- Depth: 1 to 1.5 inches, 2 seeds per spot.
- When: on or after your last spring frost date, once the soil is at least 50°F; seed is quickest to come up between 60 and 95°F.
- Succession: Utah State suggests sowing again every 10 to 14 days for a longer harvest.
See the sweet corn planting dates for your ZIP code, and how much corn to plant per person for your household. The raised bed planner fits a corn block next to your other crops.