Traditional varieties are good candidates to be grown under sustainable conditions. In this research we evaluated the effect of reducing fertilization and irrigation dose, and the use of microbial biostimulants (N-fixing + K and P solubilizing bacteria+ mycorrhizal endomycorrhizae fungi) on yield parameters of two traditional pepper varieties (BGV13004, BGV5126) and one commercial variety (Cabañeros). The treatments consisted of two fertilisation levels (100% F and 50% F) combined with two irrigation levels (100% I and 75% I). Furthermore, the effect of microbial biostimulants (B) was studied at the lowest fertilisation rate using the commercial products Bactogreen® and Agromic®. Reduced fertilisation decreased total yield in varieties BGV13004 and Cabañeros, as a consequence of reduced fruit set. On the contrary, in variety BGV5126, the decrease in the concentration of the nutrient solution (100% F vs. 50% F) led to an increase in yield, probably due to a greater sensitivity of this variety to salinity. The effect of B was highly dependent on the variety studied, with both an increase (BGV13004) and a decrease (BGV5126) or no impact (Cabañeros) on total production.