A watermelon cultivar, designated watermelon line CA9, is disclosed. The invention relates to the seeds of watermelon line CA9, to the plants of watermelon line CA9 and to methods for producing a watermelon plant by crossing the watermelon line CA9 with itself or another watermelon cultivar. The invention further relates to methods for producing triploid, seedless watermelon fruit using watermelon line CA9 as a parent of the pollenizer plant. This invention also relates to watermelon cultivars or breeding cultivars and plant parts derived from watermelon line CA9, to methods for producing other watermelon cultivars, lines or plant parts derived from watermelon line CA9 and to the watermelon plants, varieties, and their parts derived from the use of those methods. The invention further relates to hybrid watermelon seeds, plants, and plant parts produced by crossing watermelon line CA9 with another watermelon cultivar.
