Food should only be offered for short periods of time, but keeping the babies separate from the mother can encourage natural weaning kittens age. At what age do i or mum cat start to wean the kittens onto solid food and what to wean them with? Kittens should leave their homes at a minimum age of twelve weeks. Kittens are so wonderful! But they do take some special care. Weaning. Mothers usually begin to wean their kittens at about 4 weeks of age. ...