Posted: 01/08/2013 at 18:19
Well, not quite so simple. Some varieties grow fresh flowers very quickly and some don't. I have jumble hole already flowering again on 3' stems. Cut back as soon as floweriing is over, per stem. I water well then. I'm expecting flowers again on Roma and hadspen Blood at least.
Even if they don't re flower the plant is restored to a nice mound and the sooner you cut back the more likely it is to flower again
Divided astrantias......after 3 years......have more vigour than they did previously and more floriferous.