The rootstock potential of 21 bottle gourds (Lagenaria siceraria) collected from the Mediterranean region (Turkey) was investigated for watermelon with regard to plant growth, yield, and fruit quality. The Crimson Tide watermelon cultivar was used as a scion and 2 commercial rootstocks (L. siceraria) were also used for comparison. In greenhouse conditions, the survival rate of grafted plants and the effect of rootstocks on plant growth were determined. The grafted plants were planted under low tunnels in early spring and the effects of the rootstocks on early yield, total yield, and fruit quality were evaluated. The survival rates of the grafted plants varied from 83% to 100%. Survival rates of those with commercial rootstocks and local rootstocks were similar. Plants grafted onto 20-02, 31-09, 31-43, 35-01, and 46-03 were more vigorous than ungrafted control plants. Compared to the control plants, grafted plants had 37% to 80% higher plant dry weight. All of the grafted plants except CT/Macis produced a higher yield than the control plants. The plants grafted onto 6 of the local rootstocks had significantly greater total yields than those grafted onto the commercial rootstocks. Among the local bottle gourd landraces tested, the 01-16, 07-45, 20-06, 31-09, 31-15, and 46-03 were found to be promising genotypes with regard to total yield. Early yield was not significantly affected by rootstock. The quality parameters of the fruits harvested from the grafted and control plants were found to be similar except for a limited number of graft combinations. It was concluded that germplasm from Turkish bottle gourds has a high rootstock potential for watermelon with regard to the investigated parameters.