Hi, I'm not normally on this forum but I'm trying to get ideas for next year. I'm not sure what happened but the agastaches were weakened considerably, weren't they? Just spitballing here, I've found that a lot of flowers of western origin can't take much moisture especially during the winter. They may require near perfect drainage. Also, the freeze-thaw cycle so common to eastern springs might take out some plants. Also. fertilizer isn't a great idea for wildflowers or their near kin since they were developed by Mother Nature to live in infertile soil. Agastaches are not always long-lived but even less so when conditions aren't to their liking. Good luck to you. I am having to replace a few agastaches and salvias, among others, myself after the last two winters.

Thanks you so much for your comments, Kes Z. All you say makes perfect sense. Mine are planted under the eves, so it's drier, but certainly not dry as it would be in the west. One I planted out in the open didn't even make it thru the first winter. As you said, weakened, and so after a few years poof.

Actually I'm delighted it wasn't something I did (besides try to import them here. I might try them again in another spot, or I might give up. Have to think it over.

Updating: This year tried fertilizer on one patch of agastache, and presto, the ones fertilized are tall and full now like old times.

I'm in zone 6a and have tried growing the orange and red agastaches a few times. I didn't have good luck, even though they had full sun and good drainage.One plant stuck around for 2 or 3 years.The others never returned after winter.I've given up on them.I'm planting more cold hardy mints now instead, while adding some annuals like Salvia coccinia and Salvia Amistad,and Salvia gregii which is perennial in warmer areas but an annual up here.The autumn sage must have a lot of nectar,the hummingbirds and bumblebees flock to it. I grow the hardy purple agastache foeniculum.It's about as close as I can get to the orange and fuchsia ones I wish I could grow.