Naturalness arguments favour supersymmetric partners of the third generation quarks with masses not too far from those of their Standard Model counterparts. Two ATLAS searches for direct top and bottom squark pair production in final states containing no leptons are reported. In 36~$\mbox{fb}^{-1}$ of pp collisions data collected during the LHC Run 2, no evidence of a signal is found and limits are placed on the mass of supersymmetric particles.