A glasshouse experiment was conducted with young grafted kiwifruit plants to evaluate a rapid sap nitrate test using Merck nitrate test strips, and to establish critical values for maximum vine growth. Total N leaf concentration for these plants was also related to vine growth. Sap nitrate nitrogen was significantly related to growth of the plant expressed as unit leaf rate (ULR) over four and six week periods from the time of sampling. Total N, on the other hand, was only significantly related to the total cane length at the time of sampling but not to the ULR. Using Cate‐Nelson graphical method, the critical sap NO3‐N value for maximum growth was established at 500–600 ppm. The critical value for total N was established at around 3.2%.