Last spring I planted a Muhlenbergia capillaris 'Pink Cloud' and in the early fall added 5 more in the same area. None survived the winter though I have the straight species a short distance away and it's fine; I've had it for at least 5 years. Do you think I lost the cultivars because the cultivar is not as hardy as the species or because they were younger plants. We did have a 2 week stretch of considerable cold, but not colder than a normal zone 6 winter.

I'm trying to decide whether to shell out more money on Pink Clouds or just write them off and stick with the species.