I always work on the assumption that the longer a plant is in leaf, the more energy it can put into its root system, in the case of perennials. This is why trees put on thicker rings in good years and why trees in warmer climates grow more quickly.
I can't see why this doesn't apply to plants like the ones you mention, despite the energy which goes into flowering. The real problem might come if they don't get any rest at all, though I expect we will all experience a cold snap or two after Xmas.
It's much more common than we remember, these balmy periods well into December. For example, I just picked about ten beautifully ripe peppers from the polytunnel and a few handfuls of small tomatoes.
But by February, I would be amazed if everything hasn't died back ready for the next gardening year.
Enjoy your garden flowers while you can... it's a long time to May and June!

Thanks for that Bertie. Seems Like I should not worry too much. You have inadvertently answered another question I was pondering on! I was looking at Wagger's pics of Australian trees and wondering why they are so big and have huge visible roots now I know.

Bertie's right, we will get more cold after Christmas - the ground retains heat for the first part of winter, which gradually dissipates with shorter days (less sunlight), so the ground temperature in, say, March, is a lot colder than it was in November/December.

thanks

You had a DRY summer? Weren't you lucky, Denise! We certainly didn't, down here in the west country. :-((

East sussex was very dry but the last 4 weeks we have had nothing but rain.

Us too - :-((( ONE day with no measurable rainfall! We had 168 mm in November.

yes i was going to comment on how lucky denise had been but you beat me too it spritz.

Yes we had a lovely spring followed by a great summer but carnt help thinking extremes of wet and dry must stress some plants?

not to mention the gardener :o)

ha ha