Minimum planetesimal size d_min resulting in the formation of large objects obtained with different methods for different values of v_c (indicated inpanels) and d_c. The solid blue line shows d_min computedusing our multi-annulus simulations. The green line is the analytic estimate for d_min assuming that growth can occur starting from the smallest size that does not suffer erosion by any particle greater than 1% of its mass, according to the Stewart & Leinhardt (2009) prescription. The red line is the analytic estimate for d_min assuming that growth can occur as long as catastrophic disruptions are absent. The dashed blue line shows the geometric mean of the red and green lines.