I've tried various cultivars of shasta daisy over the years and usually they only last a couple of years. The longest run I've had with them was 'Alaska' that I had started from seed- those returned for 3 or 4 years. Those plants were grown in heavy clay soil that lacks organic matter. I think they benefit from frequent division, but lately I'm not having them survive long enough to divide them.
Last year I picked up a gallon pot of 'Becky' from a clearance wrack, and it formed a big, healthy mound of foliage by fall. By the end of winter it had mostly died, except for one small part (the size of a seedling). That little surviving piece has again grown into a big, healthy looking mound of foliage, and even had a couple of blooms late this summer. The spot is well drained, but the soil is rich- wondering if that could be a problem? If it survives the coming winter, should I divide it in spring?
I love the simplicity of white daisies and the light they bring to the garden, and would sure love to succeed with them! Any ideas would be appreciated...