In Entre Ríos natural fields, E. horridum Malme is an important perennial weed that may be reproduced sexually and vegetatively by rhizome. This study aims to analyze shoot activity of E. horridum rhizomes and to evaluate cut effect and rhizome age in the sprouting of the shoots. Sprouting was evaluated through rhizomes extracted from a 1m² area along a year. After recording their individual fresh weight, length and diameter, rhizomes were kept entire or cut according to its length and incubated in growing chamber. Rhizomes shoot number and length were recorded weekly. Rhizome age was estimated using data from different trials and analyzed by linear regression model. Cross-sectioned rhizomes increased an average of 3.5 times their sprouting. The shoot number per unit of rhizome mass was higher in average in the entire rhizomes than in the cut ones. Entire rhizomes were lower in length, diameter and age as compared with the cut ones showing a rate of 10.6 ± 6.7 and 37.3 ± 17.8 shoots per rhizome respectively. Rhizome diameter was the best predictor of rhizome age (r = 0.87). The number of shoots correlated significantly with rhizome length. A seasonal variation of rhizomes sprouting was observed. These results were attributed to a change in the transport of photoassimilates in favour of the flowering.