Resumo. Recent studies are focusing on native forests because of their importance on the production of timber, fruits and on the environmental conservation. One of the main aspects yet to be studied is the nutrition of the species used in these reforestations. The objective of this work was to study the demands of K and S jacarandá-da-bahia (Dalbergia nigra) seedlings. An experiment was conducted in the nurseries of Forestry Department in the Federal University of Viçosa, Minas Gerais, Brazil, using a Complete Randomized Designed, with five doses of potassium (0, 50, 100, 150 and 200 mg dm-³ of K) and six doses of sulfur (0, 20, 40, 60, 80 and 100 mg dm-3 of S) . The nutrients were applied in four split doses, 0, 30, 60 and 90 days after sowing. The height data, the stem diameter and the root dry matter were recorded after 157 days of sowing. The relationships between shoot/root ratio, plant height stem diameter ratio and the Dickson quality index (DQI) were taken. The seedling showed a negative response to potassium fertilization for most of the characteristics evaluated. The application of 30 mg dm -3 of S and 30 mg dm -3 of K is recommended for jacarandá-da-bahia seedling production for maximum dry mass production.