Hi Rosa

It's a bit limiting having to have the same plant in three sizes, but not standard type. I would also say hydrangea as the mini single head ones are perfect for tablecentres and look very English country garden.

Other than rose plants as Sosas says, what about geraniums? Passiflora pyramids would be lush for the taller ones, maybe you could team them with purple campanula for the centres?

Uhhhh...fuchsia.....azalea....impatiens....