I have also tried it a couple of times and it was pretty for a while and like yours finally disappeared. I think it's just too hot here. Too bad....it's really a cool plant.

I've had some for a couple of years. I didn't have any problem with it disappearing in the heat of the last two summers. It went through the summers well, but has not come back well this spring. All three are much smaller than they were last year. It needs humus-rich soil that doesn't get dry, so maybe that's the problem with summer heat - the soil dried out too much? Lady's mantle should grow well here. I think I'll work some more compost in around mine tomorrow and see if that helps them any.