We built a flagstone patio and walkway last year. We used sand, not mortar, and built the form with 2x4s. We recently filled in the cracks with polymer sand instead of gravel and it looks great...except for the form. I can't stand that you can see the wood form. The problem is that our patio is on a slight grade, so removing it wouldn't work, you need the form to keep the sand and stones in place.

Any suggestions to hide the form or somehow make it looks less like a flagstone patio enclosed by 2x4s and more like a nice natural stone patio and walkway?

Oh, and I have planted a ton of stuff, it is filling in and I hope will start to improve the look.