Avant Garde plants are very nice! I would give it full sun. is it in the ground or in a pot? perhaps fertilizing it every two weeks with diluted organic fish emulsion would work wonders. its a late bloomer so its got lots of time to put on new growth.
It is in the ground. This is the first time it has bloomed since I have had it , so I agree it needs more sun. I had trimmed the trees it got a little more sun and have had glorious rain this spring aswell