Anenome wild swan - beware a tricky customer!

Of the 8 new (and expensive ..) anenome wild swan I planted in May, ONE and ONE only has survived! am seriously upset. It's a gorgeous plant and one by one they have curled up their toes and died. they were part of a larger new planting I put in in the early summer. I fear it may have been a combination of my heavy soil and over watering.  the casualties mostly happened following use of my lawn sprinkler. My soil is heavy but 'improved' clay and sometimes the top inch or so can seem very dry while deeper down it's really moisture retentive so this might have been the problem. My advice is to be careful with watering - don't mistake overwatering for drought!