I have finally found the 'secret' to ginger lilies in my NE MD garden is planting on a south slope so that the soil stays warm and dry(er) in winter. This means of course they need some deciduous shade. The cultivar, of course, is also important. So here's my list of varieties that have lasted several winters at this point:
Hedychium 'Pink V' from Brent & Beckys - grows like gangbusters
Hedychium densiflorum - this isn't super happy, and probably would prefer a somewhat more maritime climate, but it does ok
It's nothing special to see a large variety of healthy Hedychiums at places like Duke Gardens and Plant Delights, but those are very mild zone 7 climates, for PDN, very very close to zone 8. Up here, I don't think I've ever seen a large patch of Hedychiums in a public garden, and only in a couple gardens of collectors. I have failed with various varieties:
H. greenei
H. wardii
and another variety from B&B failed but I can't remember what it was called...grew fine in summer but didn't survive winter. Maybe H. aurantiacum.
H. coronarium is said to be one of the hardiest, but I've never grown it
As for the other gingers: Z. myoga is super hardy and I have a patch. More a plant to grow to say you grow it, as the flowers are not very showy
Roscoeas and Cautleyas are tantalizing, but, generally, seem like they would prefer a climate with cool nights. That being said I got a 'Red Gurhka' from Keeping it Green last year, and it flowered in a pot this year. They are never super vigorous for me in the way a SE US grown/bred Hedychium is.
