Question
I have clay soil that I have amended.  It's a 2 tiered rock garden.  I have hostas, irises & lamium that grow very well.  I also have campanula that grows well.  I'm looking for something more colorful that grows in Zone 3-4, for mid to late summer.  Also, looking for fall flowers.  I have Columbine that did not grow well this year.  My bee balm also did not grow well.  I want all summer bloom, not so much work.

Answer
Hi Amy,
Thanx for your question.  Here is a URL for excellents lists of perennials for zones 3-4.  http://www1.umn.edu/webdd/resources/zoneperen.html

Also, with columbines in your zone, place them in direct sunlight and amend the clay soil with composted cow manure, this should help improve their performance.

New Zealand and Alpine asters are great for the fall as is Sedum and some chrysanthemums.  I hope this helps.
Tom