Red Sugar

Do the dark brown colored leaves look too much like the soil color

and throw off the color scheme?

Frankly, I find the photo not interesting, but to be very objective, the colors are great, and yes the brown leafs a just a bit on the dull side. Composition is good with variety of curves and straight lines. If one takes the time to arrange all the leafs in a pattern, I would take the time to remove the leafs at the two top corners. Try arrangement on other surfaces.