Final masses of planets (M_P = M_c + M_env) as a function of initial radius r₀ and initial time t₀ in discs with a metallicity of dust Z_dust = 0.1%. The top plot features a water-to-silicate ratio of 3:1, while the bottom plot features a water-to-silicate ratio of 1:3. The black, blue, yellow and white lines have the same meaning as in Fig. 5. Planets can outgrow the region of outward migration and drift inwards at lower masses before they reach runaway gas accretion, which allows for a larger parameter space for the formation of low mass planets in contrast to high Z_dust discs (Fig. 5).