Grafting is used as a common tool to increase tolerance of vegetables against biotic and abiotic stresses. However, grafted organic seedling production is not present in Turkey. This study was conducted to determine the crop performance of organically grown grafted tomato and watermelon seedlings. Rootstock and scion seeds of both species were sown in vermicompost:local peat (1:1.5 v/v) mixture. After germination in growth chamber (24/24 degrees C, 80% relative humidity (RH) for 3 days), plants were moved to a greenhouse. When seedlings had 3-4 fully opened leaves, tomato (Lycopersicon esculentum) scion 'Melis' were grafted with tube grafting method on two interspesific (L. esculentum x L. hirsutum) rootstocks, 'Beaufort' and 'Sarafin'; watermelon (Citrullus lanatus) scion 'Asbal' was grafted with slide cut grafting method on three rootstocks, 'Argenterio' (Lageneria siceraria), 'Jumbo' (Cucurbita maxima) and 'Flexifort' (C. maxima x C. moschata). Self-grafted seedlings were used as control. Grafted seedlings were left in a healing unit at 24-26 degrees C, 80-90% RH, 16 h LED lighting/8 h dark for 10 days. Seedlings were placed again into greenhouse after healing for adaptation and watermelon and tomato grafted seedlings stayed there 14 and 21 day, respectively. Ten seedlings from each replicates were harvested from for seedling performance (root, rootstock and scion length, root and shoot diameter, shoot and root fresh and dry weight). It was concluded that among the tested rootstocks, 'Beaufort' for tomato and 'Flexifort' for watermelon were found more appropriate as rootstock compared to the others due to the higher performance in root and stem length and diameter of rootstocks and scions and shoot and root fresh and dry weights.