What's the best way to water potted plants?

Chris Smith put this question to Beverley Glover from Cambridge University...

Beverley - Well, you might be. One of the biggest insults one of my gardeners at the Botanic Garden can say of another of this colleagues was that there are classic overwaterer and a classic overwaterer always waters from the top down. But actually, it doesn’t really matter which way you do it as long you don’t leave them sitting in it. So the problem with water from a plant’s point of view is that their roots need to be able to respire just like the above ground tissues, they need to be able to take in oxygen and give out carbon dioxide and they can't do that if their water logged. So as long as whichever you do, you give it a few minutes and then you drain away the excess, it will probably turn out alright.

Chris - Because someone said to me, you mustn’t water your African violet from the top because it will go rotten, and mouldy, and manky. I must admit, I did water an African violet like that. It was my wife’s and I killed. And I felt terribly, terribly guilty. Am I off the hook?

Beverley - I think you are off the hook. You would’ve killed it either way. [laughs]