Lois,
I'm not expert here and I don't live in SE PA, but I've been wanting to experiment with growing Penstemons too. One I would definitely recommend that is just stunning is "Iron Maiden". Bluestone sells it. It grows to about 2 feet and is a pure red. I love it!! Its done well in our clay soil. I didn't fertilize it or baby it at all! It bloomed for a short time, but its so worth it.

You might want to repost this in the Pennsylvania Gardening forum for some more localized suggestions. Unfortunately, my suggestions from a west coast zone 8 may not be the slightest bit applicable :-)) I can say that here, most common penstemons offer an extremely long bloom season with occasional deadheading and are more or less evergreen. Like salvias, they prefer full sun and very good drainage - sharp drainage seems to be the key in overwintering them well in our damp winter climate.

I live in Se Pa. I have had luck with Red Rocks, Husker red and also Elfin pink. The hummers sure do love them.
Joann

I have had Husker Red for a few years but haven't seen a hummer near it, although it is in another bed far away from frequent view. Last year I spent several hundred on plants for hummers & Penstemons I planted were Red Rocks, Mersea Yellow, Compactum, Elfin Pink, Sour Grapes & Pike's Peak Purple. Red Rocks & Pikes Peak bloomed almost whole summer & fall & were beautiful. Elfin Pink good too but shorter duration. Mersea Yellow & Compactum were very small, healthy plants but didn't flower. Hoping for more from them this summer. All stayed green well into winter. Saw hummers on them quite a few times but the Agastache's, Salvia's & Scarlet Runner Beans edged the Penstemons out a bit. We'll see how this nasty winter affected them soon, I suppose. I did know they needed good drainage, so instead of building a huge raised bed, I worked in sand & small gravel to my soil & made a mini mound. I cut hot caps in half & used it as a ring to hold the mound in place some & planted in the ring with the crowns just above the ring. Mounded more soil up on the outside to cover the ring & then added some small crescent pavers to further hold up the soil. Hope I created the right drainage. I winter sowed some Iron Maiden & Scarlet Penstemon this winter to try. Joni

I've been growing Huskers Red for quite a few years without any problems whatsoever.
I really love the red Penstemon eatonii, but it's soooooooooo floppy. I have yet to investigate what I'm doing wrong with this one.
Penstemon barbatus "Iron Maiden" is also beautiful, and floppy too, but not as bad as the eatonii.
I also have Red Rocks, which has been a nice performer amongst the shorter penstemons, but having said that, I don't like it's low height.
I had tried "Sour Grapes" a few years ago, but it never made it a second season; I had read that it wasn't hardy in Z6, and clearly it wasn't for me.
Someone had sent me seed for Penstemon tenuis, Gulf Coast Penstemon, which is supposedly an annual Z6. It didn't bloom last year, but the foliage is still holding on, even thru winter it has remained green, so I'm kind of hopeful that it's hardier than I read. I believe it's short though, about 18".

I'm finding that I'm preferring lobelias over penstemons, which are less floppy, although I have encountered some floppiness. I have great luck with Lobelia siphilicata and only recently had luck growing Lobelia cardinalis from seed and established plants, something I've tried in the past and usually failed at.

I had penstemons last year but cant remember the name of it. Red with a white throat, maybe its because it got little use, too much Black and Blue and lady in red , I guess.