Access to healthy planting stock is a critical issue for Switzerland. With this aim in mind, Agroscope has established a collection of sweet-potato varieties that now numbers more than 15 accessions. These varieties are kept in the nuclear-stock collection of Agroscope’s Mycology and Biotechnology Group in Changins, away from any viral, bacterial or fungal contamination. A new growing medium has been developed by our researchers in order to keep them in the best possible condition. This medium is more efficient than standard media, since it allows rapid growth of the plants without the development of annoying calluses that generally appear when sweet potatoes are raised in traditional growing media.