Knowing whether or not to water the grass can be tricky but there is one tell-tale sign to look for. ‘You can water a lawn after it has been mowed, but only if the lawn needs it,' says Stacie Smith, owner of landscape specialists Smithson Exteriors. 'A good tip is to walk across a small section of the lawn, if you look back and can see your footprints, the lawn needs to be watered.’