The mentrasto (Ageratum conyzoides L.) is a medicinal plant with analgesic effect and anti-inflammatory confirmed. The objective of this work was to analyze the growth of five accesses of mentrasto in the fields and greenhouse. The statistical design was entirely randomized with three replications in a subdivided plot scheme. Plots were constituted by five accesses of Ageratum conyzoides and subplots were sampled in five periods of time. The accesses were obtained in Mariana-MG (AMA), Piranga-MG (API), Visconde do Rio Branco-MG (ARB), and Viçosa-MG (AVB and AVP) counties. It was measured the following characteristics: aerial part of fresh biomass, dry biomass, height, flowers and essential oil content. In the access AVB the greatest rate of dry biomass accumulation was obtained, 1.2756 grammas/day, in the field and the access AVP showed the best gains of dry biomass by time unit, 0.3665 grammas/day, in the greenhouse. In both environments the most precocious blooming was obtained in the access ARB, and in the access AVB the latest blooming. The ARB access presented the higher essential oil content, which was 0.70% (P < 0.05).
