Growth maps of protoplanets accreting pebbles and gas for four combinations of the relative pebble mid-plane layer thickness, H_p∕H_g, and the pebble flux relative to the gas, ξ. Cold gas giants form readily from seeds starting in the outer parts of the protoplanetary disc when the mid-plane layer is very thin (top left plot) or the metallicity is higher than the solar value (bottom left plot). However, changing any of these parameters by a factor two increases the pebble accretion timescales enough to quench the formation of gas giants (top right and bottom right plots). Protoplanets only grow to super-Earth masses in these cases.