Potato shoots were propagated in vitro by placing nodes from sprouted tubers on Murashige and Skoog type medium without hormones. The vigour of growth and the rate of node production increased with both day-length and temperature over the ranges 8–24 h and 15–25 °C respectively. Propagation rates of up to × 10 per month were obtained. In vitro plantlets spontaneously formed roots either in agar or liquid cultures. Plantlets left in the culture jars for 3–4 months eventually senesced and formed small tubers in 16 and 24 h day-lengths. In a day-length of 8 h vegetative growth continued by branching and no tubers were formed.