Suggestions for summer periennials for a bed of primrose

Hi everyone

I'm in the process of ensuring (hopefully) that our front garden has spring and summer perennials in each bed.  However, the primroses seem to be taking up a lot of room, and I like a lovely sea of cottage cream/yellow  so I'm happy with that, but I don't know what to put in for the summer that will give the primroses room to grow and flower but in turn, will have room to grow and flower, maybe in August onwards. 

Does anyone have any suggestions please?  Colour wise, blue or pink would fit in nicely and not orange, red or yellow.