High quality, in-vitro produced bulblets should grow rapidly and flower as fast as possible after transfer to soil. Fast growth occurred in large bulblets and in bulblets that formed a stem with several leaves instead of one or two leaf-bearing scales. Since stem formation occurred more often in large bulblets, we concluded that bulblet growth in vitro is an important factor for rapid growth of lily bulblets after planting. During in vitro culture, growth of the bulblets depended on sucrose concentration. Another important factor was the size of the explant: on a large explant, large bulblets regenerated. The presence of the explant was necessary during the whole regeneration period. When bulblets were excised from the explant after 5-6 weeks, and cultured onto the same medium, growth ceased. We studied changes in carbohydrate content during regeneration in vitro as influenced by explant size and sucrose concentration. We concluded that the contact area of the explant with the medium plays a key role in determining bulblet weight. Interestingly, the heaviest bulblets were regenerated on actively growing explants that accumulated starch.