Bit of context here. I grow the hybrid and often new varieties that have the less,hardy gene in them. There are some like blue fortune and some downright "seedy" amd these will be easy to propagate.
Black Adder does survive for me if left intact. I have plants that have taken from cuttimgs and from basal tears....blue boa is easy for me. I have deliberately avoided those that seed.
I have never succeeded in dividing agastaches. They resent root disturbance and like to get roots down deep. The hotter the better for agastaches but still need a good drink every week or so.
Hapycottontail I have posted pics but waiting for little more growth. (to show off ) first. In a recent picture I had black adder, summer sky amd raspberry summer but perhaps it was bit hazy. I have one called heatwave which is "delicious" but it is, so far, quite short. Expected it to be taller so it is a little obscured .....next year it will be front of border. However, I will include it in pics.
For me....here in the very mild south west of cormwall.....agastaches are at their peak approaching mid July onwards.
Only been growing agastaches for 4 years or so therefore still learning about them.