By T5o7b8
Surrey,
United Kingdom 
which ceonothus bears the darkest blue flowers, not ground cover.
3 Apr, 2010
Answers
Bit of a subjective question, really, "darkest" blue - but I'd say Ceanothus x veitchianus (7 x 7 feet) or if you want more of a tree, C. arboreus "Trewithen blue"
3 Apr, 2010
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'thanks'
3 Apr, 2010