85 days. Open-pollinated.
Black Diamond is an heirloom watermelon variety popular in the southern regions of United States.
Vigorous vines produce dark blue-green fruits that grow to around 40 to 50 pounds each. Their tough rinds are bruise resistant and makes them excellent shippers. Flesh is bright red and firm, while the flavor is sweet and delicious.
Black Diamond Watermelon
Growth Chart
Hardiness Zones: 3 to 12 Light Requirement: Full Sun Soil Type: Sandy, loamy, well-drained Sow Depth: 1/4 inch to 1 inch Plant Spacing: 3 to 5 feet in rows 6 to 8 feet apart Germination Temp: 65°F to 85°F Germination Time: 7 to 10 days Maturation: 85 days Growing Tips
If starting indoors, sow seeds 1/4 inch deep in individual peat pots, 3 seeds per pot, and use a heat mat to maintain a soil temperature of at least 80-85°F. Germination should occur within 7 to 14 days. Thin to the strongest plant once the seedlings have developed their first set of true leaves, and transplant about a week after the last spring frost.
If starting outdoors, direct sow once the soil temperature reaches a minimum of 70°F. Choose a location with full sun and rich, loose soil, then sow 6 seeds 1 inch deep in hills. Space plants 3 to 5 feet apart in rows that are 6 to 8 feet apart. Thin to the strongest plants once the seedlings have emerged.
To protect the melons from soil contact, consider mulching around the base of each plant once the vines begin to develop. Keep the soil moist until the fruits are about the size of a tennis ball, then water only when the soil becomes completely dry.
Watermelons are ready to harvest when the tendril closest to the melon's stem dries up and turns brown, or when the underside of the melon turns from white to yellow.