‘Yo Yo’ is supposed to be 6-12″x15″ (a ‘more restrained variety’, they say), but I think this one has spread to at least 36″. There are some lovely sedum underneath that I probably need to rescue.
It’s a reliable bloomer, starting in mid-May here and continuing for a month or so, then sporadically blooming throughout the summer. The gray-green foliage is a great foil for other plants in summer.