Different types of watermelon seeds can be classified into three groups, including early, main season and seedless. Watermelon seeds are categorized based on the harvest time of the fruit, varieties and the presence of seeds within a developed watermelon. All types of watermelon seeds, however, produce plants that thrive in warm weather and a long growing season.
Early Watermelon Seeds
Early watermelons, also referred to as ice box varieties, are smaller in size and come from watermelon seeds that produce fruit with a time of 70 to 75 days to harvest. Varieties of early watermelon seeds include Golden Crown, a variety with red flesh and green skin that turns yellow upon ripening. Sugar Baby seeds produce red-fleshed watermelons that weigh 6 to 10 pounds. Yellow Baby seeds yield yellow-fleshed fruit weighing 6 to 10 pounds, according to the University of Illinois Extension.
Main Season Watermelon Seeds
Main season watermelon seeds produce fruit with 80 to 85 days to harvest. Main season watermelons are larger than early season watermelons. Varieties include Charleston Gray and Crimson Sweet, red-fleshed watermelons that weighs 20 to 25 pounds. Madera is a hybrid red variety weighing 14 to 22 pounds. Sunny's Pride as well as Sweet Favorite watermelon seeds produce fruit with red flesh with weights of approximately 20 pounds, explains the University of Illinois Extension.
Seedless Watermelon Seeds
Certain watermelon seeds produce "seedless" watermelons that, unlike varieties with seeds that can have up to 1,000 seeds per melon, display an absence of seeds. Seedless watermelon varieties harvest in 80 to 85 days and are prized for the ease with which they can be eaten. White seed casings, however, often form within seedless varieties, but the hard black seeds do not. Seeds with different numbers of chromosomes are grown together to form a hybrid that is triploid (contains three sets of chromosomes), making it sterile (without seeds), according to the University of Florida IFAS Extension. Varieties include Cotton Candy, a fruit with red flesh and a weight of 15 to 20 pounds. Crimson Trio has red flesh and weighs 14 to 16 pounds. Honey Heart bears yellow flesh and has a weight of 8 to 10 pounds. A larger variety called Tiffany yields red flesh and has a weight of 14 to 22 pounds, explains the University of Illinois Extension.