Campomanesia adamantium (Camb.) O. Berg ('guavira') is a fruit plant native of 'Cerrado' with nutritional and medicinal properties with few studies related to its ex situ cultivation, especially with use of biostimulators of soil microbiota and nutrient availability for the plant. Thus, aimed to evaluate the effect of a biostimulator on chemical and microbiological attributes of the substrate, and on growth of 'guavira' plant ex situ. Six doses of the Penergetic ® "K" biostimulator (0, 50, 100, 150, 200 and 250 g ha -1 ) were studied. The chemical attributes showed the highest availability in the substrates without and with 50 g ha -1 of biostimulator. Microbial biomass carbon reached an increase of 41.2% at the dose of 200 g ha -1 compared to the substrate without biostimulator. The order of the nutrient content, regardless of dose, including without, in the shoot was N>Ca>K>Mg>P>Fe>Mn>Zn>Cu and root was N>Ca>K>P>Mg>Mn>Zn>Cu. The leaf number (26-leaf plant -1 ) was greater in plants grown with 50 g ha -1 of biostimulator at 180 days after transplanting. The chlorophyll index decreased with increased doses. It can be concluded that for cultivation of 'guavira' in polyethylene bags the use of biostimulator is not necessary.