Teal or chocolate brown would be my suggestion.

Cute quilt. I would go for a print because it will hide any dirt and stains that happen on a baby quilt.

I like to use prints for my backings. If not a print, then I'd go with the chocolate brown or teal.

The lime green would be lovely. I like to use a completely different backing so there is a surprise when the quilt is turned over. You could also piece together scraps and then us a solid like the lime green to complete the backing.

I would use the teal/turquoise but often those brighter colors are more difficult to find. Just take the quilt in to the shop with you and find what pleases your eye! Besides, you will get lots of helpers offering their opinion! :)

Yellow or the aqua in the quilt top. I agree a print can make it a nice, reversable quilt.

I would stay away from the dark brown. The blue, yellow, green etc would be great. You might luck out and find a nice flannel print that incorporates several of the colors

Great quilt! I agree with all of the above suggestions for the backing.

i'm thinking bright sunny yellow! but that's one of my favorite colors! very nice quilt!

The green popped out at me when I looked at the quilt, but you could probably use the brown or teal, too. Why not see which of the flannel colors you can match closest to the top.