I bought a hydrangea about 7 months ago and it seems to be doing great. Its grown lots of pink flowers since Ive had it. Now, however, its growing smaller flowers that are all green. At first I thought that maybe it was just because they were young flowers and would change color but they've stayed that color.

Does anyone know what causes these green flowers? Its been pretty hot here the whole time Ive had it. Around 85 nearly everyday. Its in a shady spot under a tree and only gets a little direct sun from about 3pm to 6pm.