Lori,
I am zone 6a and I have multiple Agastaches returned from last year, which is when they were new plants and first put in the ground. With sandy soil you should have adequate drainage and actually too much winter moisture can be more of a problem. Did you leave the old stems standing until spring before cutting them out? I read that is important, helps protect the crown and roots from too much winter moisture because if they are cut in fall or early winter, with the hollow stems it allows too much moisture in winter when they are dormant. I waited till spring to cut the old stems on mine and all but 2 of mine returned (and those I probably lost because I moved them several times and they didn't have a chance to get established well enough). The new growth on all of mine appeared before I cut out the old stems. I believe Raspberry Daquiri is an A Aurantiaca variety or hybrid and Champagne is A Mexicana, both of which should be hardy in your zone. My 2 A Apricot Sorites are Aurantiacas and they are both about a foot or more tall and pretty full but a bit too early for blooms. Hopefully you will get growth of some of the seedlings as many Agastaches do reseed themselves (although if hybrids they may not be true to the parent species). My other returning ones are A Blue Boa hybrid (I wrote a post about it because it came back way larger than any stated dimensions I have seen), and also 2 A Rupestris Sunset, and one A Heatwave hybrid (not sure of the parent species of it). Good luck! Agastaches are wonderful.
