87 Days to maturity. Citrullus lanatus. Charleston Grey Watermelon Seeds. Non-GMO, annual, organic, open-pollinated, heirloom, heat tolerant, seeded, Picnic watermelon. Resistant to Anthracnose, Fusarium Wilt. Charleston Grey watermelon was introduced in 1954 by the Southeastern Vegetable Breeding Laboratory of Charleston, South Carolina. Charleston Grey produces fruits that are large, light greenish grey, 28-35 lbs., cylindrical-shaped, 22" long by 10 in. across. ~315 seeds/oz.