Stability criteria Λ(r) + q − 1 > 0 for the growing grains as a function of the surface density exponent for r = 10 AU (left panel) and r = 100 AU (right panel) and an initial dust-to-gas ratio ϵ₀ = 0.01 in both cases. Models with scale height of 5, 10, and 15 AU at a radius of 100 AU are shown in blue, black, and red respectively. The vertical axes are different in both panels. The second part of the stability criteria for growing grains: q < 1 is always satisfied in the disc models we have explored, see Fig. 1.