Summary Ecological intensification of crop production involves the use of intercrops and the rational use of inoculation and fertilization in case of intercrops including legume species. The root system plays an important role in the productivity of crops. Therefore, effects of the inoculation treatments (Nitragina) or foliar fertilization (Photrel) or a combination of both were assessed on root parameters of pea grown as pure stand or intercrops with linseed or wheat in a 3-year experiment in Poland. Crop stand composition influenced the root parameters of pea with a higher root length density (RLD) in the root fractions of 0.1–1 mm of pea in pea/linseed intercrops than in the pure stand, a higher mean root diameter (MRD) in pure pea and intercrops of pea with linseed than with wheat, and also a tendency of a higher root dry matter (RDM) in pure pea and pea/linseed than in pea/wheat in 2 out of the 3 years. RLD was higher with Photrel than with Nitragina in root fractions of 0.1–0.5 mm. Treatments did not affect the MRD, but a combination of Nitragina + Photrel increased the RDM in 1 year. Intercropping of pea with linseed and the application of a foliar fertilizer might be a strategy to improve pea root characteristics.