I agree with Sharon that the border should be darker, not the bright aqua in the picture - that may draw too much attention and flatten out the colors of the tulips more.
What I would consider doing is to perk up the tulip colors via visible quilting, investing in some 40 or 30 weight thread in a stronger/darker shade than each of the main tulip colors - and either outline just inside the shape and/or do curves to create petals. That would brighten all of it, I think, and make the tulips stand out more against the white.
Once that was done, I'd be giving the white sashing the evil eye, in view of using pastel quilting threads to interrupt them up a bit and make them less flat. I'd go pale with that. It will add color and texture without shouting.
hugs,
charlotte