ABSTRACT To keep potato (Solanum tuberosum L.) germplasm accessions disease-free and available for use, these are conserved as in vitro microplants under tissue culture conditions. The management of in vitro plants is labor intensive due to the necessity of periodic transferring of explants to new containers and fresh medium (sub culturing). The effectiveness of MS medium supplemented with sorbitol or mannitol in conservation of potato germplasm corresponding to different genotypes from Chilean native landraces (Chilotanum group) was investigated. Growth curves for modelling, describing and predicting shoot elongation of in vitro potato plants through the time in different culture media were developed as a tool to plan subculture labor for refreshing explants to new media. In MS medium without osmotic active compounds the rate of shoot elongation (k) was 1.12-1.45 cm wk-1 with 0% mortality. In media supplemented with 20, 40, and 60 g L-1 sorbitol, k value ranged between 0.58-0.35, 0.42-0.27 and 0.09-0.05 cm wk-1 respectively. Mortality was 0%, 13%, and 26% for such treatments. In case of mannitol, k value ranged between 0.14-0.25, 0.065-0.11 and 0.042-0.068 cm wk with 3%, 6%, and 26% mortality for 20, 40, and 60 g L-1, respectively. These data can be used to predict shoot elongation rate in different media that provide several alternatives of speed of growth. The information allows to design an adequate strategy for organizing the work in a potato germplasm bank of S. tuberosum, Chilotanum group.