Black Diamond, Heirloom Watermelon Seeds – 1950s Classic, Dark Green-Black Rind, Yellow Belly Ripeness Indicator

Black Diamond — The 1950s Heirloom Watermelon With a Dark Green-Black Rind, Bright Red Flesh, and a Built-In Yellow Belly Ripeness Indicator

Black Diamond is an old heirloom from the 1950s — a classic oblong watermelon that was one of the most popular home garden varieties of its era. The striking dark green to black rind covers bright red, crisp, and flavorful flesh that delivers everything you want in a summer watermelon. Black Diamond gets its name from the distinctive yellow spot — the “yellow belly” — that develops on the underside of the rind where it rests on the ground as the melon ripens, serving as a natural ripeness indicator. Fruit can grow quite large, stores well, and features the classic gray-black seeds perfect for seed-spitting contests. 90–95 days.

Why Grow Black Diamond?

• 1950s heirloom classic — one of the most popular home garden watermelons of its era
• Striking dark green to black rind — dramatic and beautiful
• Bright red, crisp, flavorful flesh — classic summer watermelon taste
• Yellow belly ripeness indicator — natural signal when perfectly ripe
• Grows quite large & stores well — impressive size and good shelf life
• Open-pollinated heirloom — save seed year after year

Growing Notes

Start indoors 3–4 weeks before last frost or direct sow outdoors after last frost when soil has warmed to at least 70°F. Sow seeds ½ inch deep in fertile, well-draining soil. Space plants 3–4 feet apart in rows 6–8 feet apart in full sun. Keep soil consistently moist. Harvest when the yellow belly spot is well-developed and the tendril nearest the fruit has dried and browned.

Packed and shipped by Box Garden Seeds LLC — heirloom seeds grown without GMOs, selected for flavor, resilience, and your garden’s success.