I have this one as well, and do not have this problem. It could be a rot disease, in which case you should treat with a fungicide. Or, it could be just a branch or two that are being broken on a regular basis (I see a stepping stone).

It is not due to injury as my other "SJ" had the same issue in another location. I will try a fungicide.

well yep, but do check that the plants are not being knocked against anything - my dogs wagging tail causes horrendous damage to my smaller penstemons (and shrubby salvias) they get woody and fragile, really easily - one of my really dainty ones is down to its last third. I have also concluded that they are just too miffy for the hurly-burly of my small garden so will not be replacing.

Find penstemons very attractive perennials, but over twenty years, I've found they generally do very poorly in our garden, lasting no more than a few years.

Must have tried to grow well over two dozen different types (species and hybrids).

The few that did survive and that are still doing well, after five or more years are: Penstemon barbatus 'Coccineus', P. digitalis 'Husker Red', P. hirsutus 'Pygmaeus', P. pinifolius and P. strictus.

I've put my general lack of success with penstemons down to our alkaline soil.

With the return of more moderate temperatures and a modicum of rain, my last two remaining plants started to perk up, producing both active growth and new flowers. However, one of them started dying last week due to the mysterious wilt disease and is now completely dead. The second now has wilted stem tips on a couple of branches. Hmmmph. I am done with this cultivar.

Yes this does sound like what has and is happening to my remaining `Sweet Joanne`.

I recently sprayed with a fungicide. It is to early to tell if that will have any effect.

I bought this particular Penstemon because of GW member echinaceamaniac`s rave review. I bought two very late last fall. They both overwintered just fine and the one remaining has given lots of flowers from July onwards but stem by stem it is wilting. The other one but the dust sooner.

UPDATE:

I did spray a few times with a fungicide and coincidentally or not no more stems succumbed to the 'wilt'. In fact here is a picture taken just this afternoon of the plant in question and even after one heavy frost on Friday night it looks fine (it is floppy due to heavy rain today) and still has a few flowers.

How much are you watering and what is your soil like? Penstemon in general like very well drained soil and want average moisture to somewhat dry conditions and not a whole lot of nutrient load. If you take a look at the list of varieties that SunnyBorders has had success with, those are varieties that are more tolerant of heavier soils with more nutrients. 'Sweet Joanne' is a x mexicali hybrid, which I've found handle more nutrient load than some other penstemon but still need well drained soil to do really well.

The Plant Geek
www.confessionsofaplantgeek.com
www.botanophilia.com

This SJ has gotten very little supplemental watering (with the seasons being warmer and drier each year I like that). But it is true that it is in a bed which is heavily amended ie lots of compost...very rich for the top 6".

It has already made it through its first winter in its present location so I can surmise that drainage is just fine

Consider that many native penstemon may be suited to wet winters and dry summers so it's response to moisture in winter may be different than in summer. Not sure where you live but think about what the natural weather cycle is where you are and see if it prefers less supplemental care!