Lee in Richmond

I decided to have fun with a sampler quilt. I downloaded 12" blocks and set to work, without thinking about how in the world to sash it... In the closeup picture you can see a few colors laying behind some of the blocks, in the larger pic are all the blocks I have done so far. I don't have enough of any one of these pastels to do 2-1/2" or so sashing. But maybe it should be a deep color? Or do all the horizontal sashes have to be the same color? I am just lost...