Better yet, use either bleached muslin or white PFD (prepared for dyeing) fabric. You'll want a white fabric to start with so your colors come out true. Any fabric can be turned into PFD by prewashing (with Synthrapol is good, but not necessary), and using no fabric softeners, dryer sheets, etc that add chemicals back onto the surface.
You can use fabric paints, acrylic paints, acrylic inks, colored pencils, crayons, fabric markers, dyes, or any number of things to add color to fabric. With watered down acrylic inks, you could put a wash over the printed photo instead of under it. You could also use photo editing software to just print your photo in green ink. Washability is a factor in whichever method you choose, so consider that aspect before you decide. Sounds like a great project...wishing you much success.