Verigated thread in bright greens/yellows. Beautiful - I am inspired to get the one I started - same fabric - different pattern (think it is called Garden Wizard) and get it finished. I too am using black for the background. Will be intereste in seeing what thread choices you use which might help me make up my mind which color thread to use for mine. Thanks for sharing this one.

GREAT!!!!!!!!!!!!!
I agree with everyone who says variegated thread. Superior thread is the best Variegated thread for machine quilting, and I'm particularly pleased with Rainbow, because NO LINT.

Forget all you've heard about using RAYON. The Brothers Reps at the Sit And Sews I've been at say all the hype about Rayon being the best thread is just that - HYPE. Polyester is better - because it has much less lint, more colors and it's cheaper!

And I'd practice a lot on something else first. Lots of loops would look great to complement the angles in the blocks.
It's going to be a gorgeous quilt - it's already gorgeous!

As for color, there are a lot of variegated threads in the Rainbow line to choose from, and you can't make a mistake!

Gosh this is so pretty!! I think I would go with a neon green.

I've used Madeira rayon for decorative stitches on quilts and it was beautiful!