There was an 80s kids show on UK television. My memory is poor, but here goes:

There was a magic tree or seeds that made the tree grow sweets and useful household objects.

The only other thing I remember is a green, fat monster.

Do these few details ring a bell for anyone? What was this show called?

Sorry. I don't remember more.

Was there a witch in it? Was it Wizzy Witch?

Greenclaws!

I've been trying to think of what it was called too, he put the seed in a pot in his tummy and it grew