Answer: Coreopsis usually blooms all summer long so your plant is either slow because of a cool spring season, it is not getting enough sunshine (which is doubtful in your case) or has gotten too much fertilizer (which can slow flowering). There's not much you can do to encourage flowering other than to hold off on fertilizer. I think your plant will eventually flower for you. If you want to prune it back a little to encourage new growth, it may set flower buds, as well. Hope this helps.
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