This study aims to evaluate the effect of substrates and container content on growth and quality of Peltophorum dubium seedlings. The design was completely randomized in a factorial arrangement (2 × 9), with two containers sizes (125 cm3 and 280 cm3) and nine substrates formulated from the mixture of subsoil (S), vermicompost (V) and commercial substrate (CS), in the following proportions (v:v): S100, V100, CS100, S75 + V25, S50 + V50, S25 + V75, CS75 + V25, CS50 + V50 and CS25 + V75, with nine replicates. We assessed seedling height, stem diameter, root and shoot dry matter, height/shoot dry matter ratio; Dickson quality index; and percentages of nitrogen, phosphorous and potassium in the shoot. The use of the 125 cm3 dibble tube containing 100% vermicompost allowed for higher quality of Peltophorum dubium seedlings.