ABSTRACT Arrowroot (Maranta arundinaceae), a traditional plant used to extract medicinal starch that is gluten-free and of excellent nutritional quality, is understudied for its growth and development in the organic crop system. The objective of this study was to evaluate the growth and photoassimilate partitioning in plants of two cultivars, Comum and Seta arrowroot. The design was performed in random blocks with four repetitions. At 57 days after planting (DAP), the plants were collected at regular intervals of 25 days throughout the crop cycle, and the dry mass was determined. Growth analysis was performed using the primary data. The cultivars Comum and Seta show maximum absolute growth rates of 10.51 and 12.42 g plant−1 day−1 and the maximum leaf area index (LAI) of 18.74 and 14.62, as recorded for 216 and 205 DAP, respectively. The higher absolute growth rate and higher growth of arrowroot plants in a shorter time indicate greater precocity of cultivar Seta compared to Comum. The photoassimilate partitioning is balanced between the aerial parts and rhizomes at the end of the cycle. Both cultivars can be recommended for the organic crop system in the Zona da Mata region of Minas Gerais.