I have found that the western native Penstemons need a drier winter than I have. Cold wet soil in late winter or early spring has done in about a half dozen selections and species western Penstemons though I have been successful with some that are hybrids or selections of those from areas with average moisture.

Rocky Mountain penstemon is a popular landscape plant here (surprise surprise right?) and one of the first penstemons I ever grew. It tolerates moisture and heavy soil a little better than some of my others so it might be a decent choice for people further east. They are short lived (and the heavy wet soil probably has shortened it’s life expectancy some) but they reseed with reckless abandon as long as you don’t mulch. Mildew has never been a problem for any of my penstemons.

Yea, cold wet winters here, too; but, my soil is nice with no clay and very quick draining. It sounds like this particular one might survive. Seed is cheap, so no big deal if only get a couple seasons out of it -- but I won't tolerate mildew.

My Penstemon plants have always been healthy regardless of winter survival, and my soil tends to be well-drained, but when the soil is frozen as it is most winters, we typically have two or three weeks of “mud season” where snow melt and rain water sit on the surface waiting for soil to thaw enough to allow drainage. I had them in flat to only slightly sloped beds, and planting on a steeper slope might help.

I'm just outside of Boston and winter-sowed Penstemon strictus seed about three years ago and it grew into a good plant which has kept going since then in my regular organically-rich, moisture-retentive, New England garden loam. I can't explain it but there it is. This is despite some very rainy springs. Very glad to have it in my garden. This experience was probably the single most important factor that made me fall in love with Penstemon, here far from primary Penstemon country.