the roses all sound like good blenders. the quince and the spirea will bloom together. the bougainvillea is a house plant even in z8. it's all good i think, although red brick is a hard background to deal with. just avoid the dot of this dot of that colour effect and i think you are on your way.

I'd put in a lot of green or grey foliage, repeated, to tone it down. And I agree to avoid the blob effect at all costs. Can you split the day lilies and agapanthus so you have three or five plants?

many gardeners forget that green is also a colour and the most important because it's around a lot longer. good foliage really makes the garden.

Thanks for the advice--you are undoubtedly right about foliage. I wish so much of it wasn't grasses. The daylilies already replicate themselves, but I could always buy more agapanthus. I'm hoping the ivy picks up as a grouncover; its the newest plant entrant, and so slow and tiny. I wish it would eat the house properly (I know, invasive species, damage to brickwork, yadda yadda, but still really attractive not-fifties-brickwork background color...) (I should probably have mentioned the bougainvillea's in a big blue pot that I never remember to bring in; 3 winters and still ticking, although I could lose it any time.)

Whenever I worry about too many different colors....I think about zinnias! They always look beautiful together :)

Lots of white and green can really tie the garden together, too. Maybe white alyssum under everything and lots of green in the background (as mentioned above).