Here's a useful tip on Carrots from my Introduction to Permaculture book:
You can cut the tops off your carrots, then cut these tops into quarters, place on damp cotton wool and they will sprout within a week. Once the sprouts grow a few centimetres they can be replanted into the garden to grow more carrots.
That's four new carrots from each carrot you eat! Works too, I've got a whole saucer of cotton wool with sprouting carrot
tops, they'll be going into the garden next weekend. Parsnips can be propagated the same way. That's 4 new carrots and 4
new parsnips from each one you eat. Well, to be truthful, I haven't harvested any carrots or parsnips yet, but I have planted
quite a few cuttings now and they all seem to be growing well.
Offered by Gino.