The effects of five levels of nitrogen (N), phosphorus (P), and potassium (K) and B-Nine (B9) on Brompton stocks (Matthiola incana) grown in peat/sand 1:1 (V.V.) were studied. Nitrogen strongly promoted growth which was further enhanced by high K. Deficiency symptoms occurred at low K whereas there was little demand for P, and it tended to depress the response to N. A foliar spray of B9 strongly reduced height and was temporarily phytotoxic at 5000 and 6000 ppm. The two concentrations offset the response to N particularly at 450 and 600g N/m3 where there was a mild N X B9 negative interaction for foliar dry weight.