 This requires planting pollinizer rows of varieties with viable pollen.Since the supply of viable pollen is reduced and pollination is much more critical in producing the seedless variety, the recommended number of hives per acre (pollinator density) increases to three hives per acre (1,300 m2 per hive).Watermelons have a longer growing period than other melons, and can often take 85 days or more from the time of transplanting for the fruit to mature.