This work was realized with wheat as test plant in greenhouse conditions. Pots of 0.6, 6 and 10 kg capacity were used and the wheat was harvested at 30, 60, 90 and 120 days after germination. The evaluation of fertilizer response was based on the production of the 10 kg capacity pots, harvested at 120 days after germination. At this time a clear response to nitrogen, phosphorus and potassium was obtained. With pots of 0.6 kg capacity, it was possible to study phosphorus and nitrogen by harvesting at 60 days after germination. With Mitscherlich pots (6 kg capacity) it was possible to study phosphorus by harvesting at 30 days, and nitrogen by harvesting 60 days after germination. Response to potassium fertilizer was observed only where plants were harvested 90 days after germination.