How far apart to plant watermelon
Virginia Cooperative Extension and Colorado State University Extension space watermelon plants 3 to 4 feet apart in the row, with rows 5 to 10 feet apart. In a raised bed, plan on 3 to 4 feet each way, and the UC Master Gardeners square foot guide gives one watermelon every 2 squares.
The wide row spacing is for the vines, not the roots. A plant sits in one spot, but its runners spread across the paths, so a watermelon row takes as much space as several rows of smaller crops.
How many watermelons fit a raised bed
| Bed | 42 in each way (square) | Square foot method (1 per 2 squares) |
|---|---|---|
| 4 × 4 ft | 1 | 8 |
| 4 × 8 ft | 2 | 16 |
| 3 × 6 ft | 0 | 9 |
| 4 × 12 ft | 3 | 24 |
The first column is the calculator's default: 42 inches, the middle of the 3 to 4 ft range, with half a spacing kept clear along each edge. A 3 ft wide bed is narrower than one plant's share at that spacing, so the count drops to zero; set one plant in the middle by hand, or switch to the square foot column or to rows. The square foot column packs the bed to its edges and counts the soil, not the vine: at 16 plants in a 4 × 8 bed, the runners must go over the sides or up a support.
In a single row, 42 inches between plants gives 2 plants in 10 ft, 5 in 20 ft and 7 in 25 ft.
How deep and how many seeds
Sow 1 to 1½ inches deep. Utah State University Extension plants 4 to 6 seeds per mound and thins to 2 plants once they have two leaves. Colorado State sows 1 to 2 weeks after the last frost; Utah State waits for 65°F soil, and Oregon State University Extension lists 60°F as the minimum for germination. In short seasons Utah State recommends transplants, grown for about 6 weeks, which ripen about 2 weeks before seeded melons. Your dates are on the watermelon planting dates page.
How many plants do you need?
Utah State suggests 3 to 4 plants per person for eating fresh and 6 to 8 if you also preserve. For a family of four eating fresh that is 12 to 16 plants, or 42 to 56 ft of row at 42 inches apart.
Is it ripe?
Utah State gives three signs to check together: the curly tendril opposite the melon has turned brown and dry, the spot where the fruit rests on the ground has gone from white to yellow, and the skin has lost its shine. Most varieties take about 85 days from seed (Colorado State).
Using the calculator
The calculator opens on a 4 × 8 ft bed at 42 inches, square pattern. Rows uses 3.5 ft in the row and 7.5 ft between rows, the midpoints of the published ranges; Area counts plants for a patch in square feet or acres. For melons in a small garden, the plant spacing calculator and the raised bed planner help fit them next to other crops.