90 Days to maturity. Citrullus lanatus. Cal Sweet Watermelon Seeds. Non-GMO, annual, open-pollinated, heirloom, heat tolerant, seeded, Picnic watermelon. Cal Sweet Watermelon fruits typically weigh 20 to 25 pounds with distinctive light and dark green stripes with bright red flesh. Calsweet has a tough rind and is a good shipping melon if grown with stress. Watermelon prefers full sun and warm to hot temperatures—plant in mid to late spring. Watermelons are also packed with rich antioxidants such as lycopene. Calsweet has demonstrated resistance to fusarium wilt ~675 seeds/oz.