Reading through this thread I've come to the conclusion that most of you only watch gardening programmes so that you can criticise . If the presenter is not dressed like a scarecrow with mud and cow $hit on his boots and doesn't speak with a broad local accent, preferably a northern one, then he's/she's no good.
You are criticising Monty Don for being rude, you have no way of knowing what the conversation between the two was immediately before the bit you saw because it probably ended up on the cutting room floor. If you take something out of context then it can sound rude, nice, stupid etc. That's a problem with the editor/director not the presenter.

Since you all seem to know exactly how a gardening programme should be presented, I'll issue a challenge. All of you get together for a weekend and make a gardening programme and put it on U-Tube so the rest of us can look at it and praise/criticise it and the presentation as required.