An inkjet printhead with an array of nozzles (26) and corresponding heaters (10) configured for heating printing fluid (20) to nucleate a vapor bubble (12) that ejects a drop (24) of the printing fluid through the nozzle. Drive circuitry (22) generates an electrical drive pulse to energize the heaters (10) and is configured to adjust the drive pulse power to vary the vapor bubble nucleation time. By varying the power of the pulse used to generate the bubble, the printhead can operate with small, efficiently generated bubbles during normal printing, or it can briefly operate with large high energy bubbles if it needs to recover decapped nozzles.