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Excessive N application occurs in greenhouse vegetable production. Monitoring methods of immediately available soil N are required. [NO3&minus, ] in soil solution, sampled with ceramic cup samplers, and [NO3&minus, ] in the 1:2 soil to water (v/v) extract were evaluated. Five increasing [N], from very N deficient (N1) to very N excessive (N5) were applied throughout three fertigated pepper crops by combined fertigation/drip irrigation. The crops were grown in soil in a greenhouse. Soil solution [NO3&minus, ] was measured every 1‒2 weeks, and extract [NO3&minus, ] every 4 weeks. Generally, for treatments N1 and N2, both soil solution and extract [NO3&minus, ] were continually close to zero, and increased with applied [N] for treatments N3&ndash, 5. The relationships of both methods to the nitrogen nutrition index (NNI), an indicator of crop N status, were assessed. Segmented linear analysis gave R2 values of 0.68&ndash, 0.70 for combined data from entire crops, for both methods. NNI was strongly related to increasing [NO3&minus, ] up to 3.1 and 0.9 mmol L&minus, 1 in soil solution and extracts, respectively. Thereafter, NNI was constant at 1.04&ndash, 1.05, with increasing [NO3&minus, ]. Suggested sufficiency ranges were derived. Soil solution [NO3&minus, ] is effective to monitor immediately available soil N for sweet pepper crops in SE Spain. The extract method is promising.