West Sussex,
United Kingdom 
Salvia 'Hotlips'. The plant is 3 years old and beginning to sprawl too far. It has bloomed beautifully all summer and until a week ago but the blooms have succumbed to a couple of mild frosts When is the best time to cut it back please?
17 Nov, 2020
Answers
I agree Rosie is excellent.
I usually give royal bumble a light trim and use the material as cuttings, giving the plant a hard cut back in mid spring.
18 Nov, 2020
Thank you, all three. I will definitely look up Rosie Hardy's video. Delighted to hear that I have a good chance of success with cuttings!
20 Nov, 2020
Check out Rosie Hardy's video here:
https://www.youtube.com/watch?v=fD-oMMOJDSo
She runs Hardy's Plants and has won 20 Gold Medals at the Chelsea Flower Show, so she knows what she's talking about
17 Nov, 2020