Mine have been in over 15 years and still going strong.

You can take cuttings, but most will survive the winter if you don't cut them back until the spring. Some varieties are a bit tender so cuttings are always good insurance.

The ones with narrower leaves are the hardier ones. A hard winter will kill them, but they'll be ok in a average winter. It's fun to take cuttings tho - they are easy from Penstemons and you can give them away to friends.

In November if you can get some leaf mould or compost and spread it about 4" thick over the crown your penstemon should survive a cold winter. Also don't cut the stems down in autumn. Wait until early April to remove the mulch and prune off the old stems.