I have made similar quilts like this with jelly rows and I'll tell you what I'd do. First I would use white to frame it in a 2.5" first border. Then I would pick any color that goes perfectly with one fabric in the quilt top and use that as a second border making it about 5 inches finished. Sometimes I end up making about 3 or 4 borders using various colors interspersed with white. My quilts always turn out great.