The utility model relates to a farming technique specifically discloses watermelon device of growing seedlings, and it is including soaking the case, soak case and bag draw together the upper portionthat separates by the baffle heating space and lower part soak the space, be equipped with first float and heater on the lateral wall of heating space, soaking and being equipped with the adapter cavity in the space, the bottom of adapter cavity is higher than the bottom of soaking the space, the adapter cavity with soak the space and pass through the siphon intercommunication, be equipped with water replenishing mechanism on the baffle, water replenishing mechanism is connected gliding pivot about and including locating admission port on the baffle, rotating with the baffle, fixed and locatethe intraoral paddle of feedwater and fix the sprue in the pivot upper end with the pivot, is equipped with centrifugal in the sprue, the bottom of soaking the space is equipped with the second floatthat can promote the pivot and shift up, the bottom of soaking the space is equipped with the drain valve, and the outside of soaking the case is equipped with the control lever, and the upper end andthe first float of control lever are connected, and the lower extreme of control lever can stimulate the case slip of drain valve, the device can make the process of soaking more convenient.