Tom Watson Watermelon Seeds. 90 Days. Non-GMO, heirloom, open pollinated seeds. Citrullus lanatus. AKA: Ole Tom Watson. A very old heirloom variety originating from the state of Georgia, dating back over 120 years. This variety produces very large watermelons that can weigh as much as 40 pounds, with most averaging around 25 pounds. About 400 seeds per ounce.