Several sensor systems are available for ground-based remote sensing in crops. Vegetation indices of multiple active and passive sensors have seldom been compared in determining plant health. This study was aimed to compare active and passive sensing systems in terms of their ability to recognize agronomic parameters. One bi-directional passive radiometer (BDR) and three active sensors (Crop Circle, GreenSeeker, and an active flash sensor (AFS)) were tested for their ability to assess six destructively determined crop parameters. Over two years, seven wheat (Triticum aestivum L.) cultivars were grown with varying nitrogen supplies. At three developmental stages, the crop reflectance was recorded and sensor-specific indices were calculated and related to N levels and the crop parameters, fresh weight, dry weight, dry matter content, N content, aboveground N uptake, and the nitrogen nutrition index. The majority of the tested indices showed high r²-values when correlated with the crop parameters. However, the accuracy of discriminating the influence of varying N levels differed between sensors, growing seasons and developmental stage. Visible- and red light-based indices, such as the NDVI or simple ratio (R₇₈₀/R₆₇₀), tended to saturate with increasing crop stand density. The best relationships were found for N-related biomass parameters with r²-values of up to 0.96. The near infrared-based index R₇₆₀/R₇₃₀ was the most powerful and temporarily stable index indicating the N status of wheat. This index was delivered by the BDR, Crop Circle, and AFS. Active spectral remote sensing is more flexible in terms of timeliness and illumination conditions, but to date, it is bound to a limited number of indices. At present, the broad spectral information from bi-directional passive sensors offers enhanced options for the future development of crop- or cultivar-specific algorithms.