Have you planted it yet? I have agastache "Cana" in a large pot that I overwintered in the garage. I don't know how long I'll be able to get away with that, but so far so good!

It's hard to resist that temptation sometimes. I have the native agastache so of course it's fully hardy. The butterflies and goldfinches just love it, I think it's very attractive and low maintenance, and it re-seeds like crazy. Let me know if you want to trade something for some.

Grow it in a pot as deeje does, and put it in an insulated box in the garage. Should do fine. Or, for herbaceous materials, just because it says zone 5, doesn't mean it's not hardy. Grow it in lean soil, no extra watering in the fall, with mulch. Wouldn't be surprised if it comes through.

I just Googled the plant and highcountrygardens.com says it's zone 4 hardy.

I'm betting it's marginal so mulch, mulch, mulch.