Transplanting
If transplanting cucurbits, grow plants in bare soil or through plastic mulch. Transplants are used for early production when market prices are high and to decrease seed costs for expensive hybrid seed. It is best to use high-quality, uniform, disease- and insect- free plants. Transplant size is critical to establishment success and plants should have no more than two to three true leaves at planting. Plants should be handled and planted carefully as cucurbits are sensitive to transplant shock. Root replacement is slow, so don’t crush or root prune plants. Plants can be hand or machine planted. Water the plant trays before planting and then water the field as quickly as possible after planting. Starter fertilizers with high phosphorus concentrations help to stimulate root re-growth. Newly transplanted fields should be watched closely; provide additional water to the plants if needed. This ensures good root growth out of the root ball and more uniform establishment and plant growth.
To produce seedless watermelon, it is important to understand that triploid (seedless) watermelon flowers do not produce enough pollen to adequately pollinate themselves. Therefore, a pollen source must be available to achieve acceptable levels of fruit set. A diploid (seeded) cultivar planted within the crop can serve as the pollenizer.
Research suggests that 25%-33% of the plants in the field should be diploid (seeded) to produce enough pollen for good fruit set in the seedless crop. You can accomplish this by planting the pollenizer between every third and fourth triploid plant within the row. First plant your seedless crop at your normal in-row spacing, then come back and plant the pollinizer periodically down the row. By planting the pollinators in-row rather than having a dedicated pollen row in the field, you increase the number of triploid plants and the yield of seedless watermelons harvested per acre. These pollenizer cultivars commonly have non-marketable fruits, may be all male plants (pollen producing only), or may produce mini- or palm-sized fruits. If you have a market for the seeded fruits, make sure the seeded and seedless watermelons look different from each other at harvest so they are not mixed before going to market.