Summary The effect of various combinations of fulvic acid (FA) and humic acid (HA) in a water culture had been analyzed with respect to growth, flowering behaviour, and mineral nutrition of the perennial woodland herb Scrophularia nodosa (Scrophulariaceae). In comparison to a nutrient solution without complexing agents or with either FA or HA, combinations of FA and HA in the ratios 2:1, 1:1, and 1:2, significantly stimulated plant growth without affecting the roots. A FA/HA-ratio of 1:2 increased flower production by 60 to 80 %, compared to the solution without and with EDTA, FA, and HA as complexing agents. The presence of HA and/or FA strongly diminished the uptake of calcium, iron, and phosphorus and their concentration in roots. The effects of FA and HA alone or in combination on the mineral nutrition of the shoot was small and specific for the various humic compounds.