We can think of two reasons your ancestors used salt on growing cabbage: 1. to deter caterpillars and 2. to deter magnesium deficiency. By adding some salt to the watering can and sprinkling on young cabbages, it hinders the growth of caterpillars, a destructive pest to cabbage. And you can add Epsom salt to the base of cabbage plants to prevent magnesium deficiency.
We can think of two reasons your ancestors used salt on growing cabbage: 1. to deter caterpillars and 2. to deter magnesium deficiency. By adding some salt to the watering can and sprinkling on young cabbages, it hinders the growth of caterpillars, a destructive pest to cabbage. And you can add Epsom salt to the base of cabbage plants to prevent magnesium deficiency.