Black Diamond Watermelon

Citrullus lanatus

Contains ~ 20 Seeds per packet

Germination 85% Mar 2026

Packed for 2026

Origins and History
Black Diamond Watermelon is a classic American heirloom that originated in the southern United States, where it was selected for its ability to thrive in hot, humid conditions and produce exceptionally large, sweet fruit. Popularized in the early to mid twentieth century, it became a staple variety for home gardeners and small farmers due to its vigorous growth and dependable yields. Its preservation through open pollinated seed saving reflects a long tradition of regional adaptation and flavor driven selection.

Appearance and Characteristics
This variety produces large to very large round fruits, often weighing 30 to 50 pounds under ideal conditions. The rind is thick, smooth, and dark green to nearly black, providing excellent protection for the deep red flesh inside. The flesh is firm, crisp, and intensely sweet with classic watermelon flavor. Vines are strong and sprawling, capable of supporting heavy fruit set when given adequate space and nutrition.

Culinary Uses
Black Diamond Watermelon is prized for fresh eating and sharing, making it ideal for gatherings and summer events. The dense, juicy flesh slices cleanly and holds its texture well. It is excellent eaten fresh, cubed for fruit salads, or blended into beverages and frozen treats. Its traditional flavor profile makes it a favorite for those seeking a true old fashioned watermelon experience.

Growing Tips
This watermelon thrives in full sun and fertile, well drained soil rich in organic matter. Consistent watering is critical during early growth and fruit development, though water should be reduced slightly as fruits mature to enhance sweetness. Black Diamond Watermelon performs best as a warm season annual in USDA Hardiness Zones 4 through 11, requiring a long, hot growing season. Ample spacing is essential to accommodate its vigorous vines and large fruits.

Sowing and Maturity
Seeds should be direct sown after the last frost once soil temperatures reach at least 70°F. Plant seeds 1 inch deep in hills or rows, allowing generous spacing. Germination typically occurs within 7 to 10 days. Black Diamond Watermelon reaches maturity in approximately 90 to 100 days, depending on climate and growing conditions.

Harvesting Guidance
Harvest fruits when the ground spot turns creamy yellow, the nearest tendril dries completely, and the rind develops a dull sheen. The melon should sound hollow when tapped. Use a sharp knife to cut the fruit from the vine to avoid damage. For best flavor and sugar content, allow melons to fully ripen on the vine before harvesting.