if you look along the longer stems towards the base you should see small side shoots starting to grow. Trim the plant back to 6" or so and then these will grow away. If there are any strong bits of growth on the top bits you chop off you can then put those into compost and see if they root for you. I did mine this week in between the snow flurries.

cuttings about 3" long remove all the lower leaves leaving about 4 top leaves in place. pop them down the sides of a small pot and keep warm. on a windowsill is good. pop the pot into a plastic bag to help it stay moist. roots should be visible in 3-4 weeks. then pot them on and you have free plants.

It should be dead headed after flowering, unless you want the seed, try cutting back the old flower stems now and see how it looks, if it's still unruly, trim back a little bit further, you can do it now, Derek.

Sorry Sbg, crossed again, but yours is a better answer lol, Derek.

Thanks both - much appreciated. I think I'm going to be busy tomorrow!

I dont mind Derek. I often forget to dead head mine so I regularly go through this routine. The plants then provide me with spare plants to sell at my charity plant stall.

I had several fire bird penstemon and follow the advice of s. B g . I also dead head regularly to keep display going until the first frost.
With last winter's cold dry weather I did lose one plant and that was in the fairly mild southeast.I normally cut right done to the base stems when flowering has finished and cover plants with thick layer of compost for protection.
Thin leaves penstemon generally Hardier than the<wider leaved variety.
Happy Gardening.!