Grafting of vegetable transplants is a unique horticultural technology, which was adapted from the practice in perennial crops. However, rootstock/scion combinations may affect and alter the final size, yield, and quality of fruits of grafted plants, both immediately postharvest and during prolonged storage. We evaluated the effect of two rootstocks [TZ148 and Nurit (commercial Cucurbita spp. hybrids)] grafted on one scion (seedless watermelon cv. 1262) in two plant stands (2500 and 5000 plant ha-1), on plant viability, number of marketable fruits (fruits weight above 5 kg) and fruit quality after one week storage at 20°C, in non- or disinfested soil. Soil disinfection significantly improved the viability of non-grafted plants. All grafted plants significantly performed better vine vigor, with no wilt or vine decline symptoms, in either disinfested or non-treated soil, regardless of the type of the rootstock. Plant stand did not affect plant viability. The number of marketable watermelon fruits per m2 was 75 to 700% higher in grafted plants than in non-graft ed. Grafting on Nurit produced significantly more marketable fruits than grafting on TZ148. The quality of fruits harvested from grafted plants was significantly better than non-grafted fruit in both plant stands and soils. Watermelons harvested from Nurit-grafted plants had better taste and texture and almost seedless compared to control and TZ-148-grafted plant.