Cyclohexane-1,3-dione derivatives of the formula ##STR1## where A is an unsubstituted or substituted, saturated or unsaturated 4-membered to 7-membered heterocyclic structure which contains from 1 to 3 nitrogen atoms and may be fused to an aromatic radical, R.sup.1 is hydrogen, methoxycarbonyl, ethoxycarbonyl, methyl or cyano, R.sup.2 is alkyl and R.sup.3 is alkyl, haloalkenyl or propargyl, and salts of these compounds, are useful for controlling undesirable plant growth.