Anyway, I just put in some Nepeta which is a beautiful blue (Walker's Low) and so far so good. Anemones are not fussy either and you can get pretty pinks. I have Honorine Joubert which is white and they are just showing buds now. Very pretty in bloom.

Aquilegia and Iris are good choices. Also, ajuga has wonderful blue flowers in spring and is a good ground cover, too. Echinacea attracts goldfinches and it is fun to watch them perch on the seed heads. Eupatorium (Joe Pye Weed) is pretty, too. I love phlox but you may get powdery mildew, so if that bothers you or if it is a spot that everyone will see up close, that might not be the best. Perfect from a distance though.

If you want a large shrub or small tree, try Vitex Agnus (Chaste Tree). It has beautiful blue flowers. I have two and just started to limb them up to more of a tree form this year. Of course, crape myrtles come in just about any shade of pink or purple you could want.

I do use annuals for color and one of my favorite blues is Plumbago. So pretty in the ground or in containers. For a spot that is easy to water (I have the best luck near the bird baths where I dump and change water daily), Astilbe comes in many pink shades and is beautiful with hosta which can be your chartreuse color. Hosta will do fine with sun as long as you water, so putting the astilbe, hosta and plumbago together would be spectacular, IMHO. Limelight hydrangea also likes some sun and would give you the green which then fades to a pinkish shade.

Clematis has all those colors, so if you have a support for them to climb, those would be great. I don't have so much luck with them, but I know many here have spectacular examples. Camellias are evergreen and come in pinks and whites, too.

Not sure if you are looking for big plants or small, but maybe this will give you a start. Others will chime in with even better ideas, I am sure!

Just visit your local nursery and see what appeals to you. This time of year, I also buy some pansies which overwinter wonderfully and start me out with purples and blues in the spring (until they get leggy and have to come out). I have even had blooms poking through snow. Fun.