A procedure based on blade area changes was used for predicting the P status of young, field‐grown sugarbeet plants. Plants from two field P‐fertilizer experiments were removed and transferred to nutrient solutions with and without added P. Measurement of changes in blade area and total leaf length of selected leaves from seedlings transplanted to culture solution with and without P provided an index of the P status of field‐grown plants. Disadvantages of the technique are that: 5 to 10 days are needed to establish that a P deficiency exists, and the method is difficult to adapt for routine work. Nevertheless, the procedure may be useful in research studies.