I know this is an old thread, and I'm new on here and finding it hard to get to and navigate some of these topics, such as Erodiums and Rock Gardens.
I want to say that there is NO WAY Erodium 'William Bishop' is hardy in zone 3. It is not hardy in my zone 4.
By the way, 'William Bishop' is the new name for the popular 'Bishop's Form'. Using the name 'form' was not acceptable under the nomenclature rules. Using the name 'William Bishop' better honours the person that this hybrid is named after.
