As there's virtually no difference between landing on a hard surface, and landing on grass with respect to technique, flare height, sped, etc, perhaps the difficulty may be the size of the runway. If you're used to landing on a wide runway and are now landing on a narrower runway, you may be flaring late and bouncing because you perceive yourself higher (narrower runways look farther away) than you really are.
Depth perception shouldn't be appreciably different on grass vs. tarmac/macadam. You're doing the same things, using your peripheral vision as well as viewing the end of the runway (as opposed to staring at a spot right in front of the nose), and using the same speeds. No differences, there.
Be aware that landing on grass is more forgiving; it allows one to "cheat," in that the long axis not being exactly aligned with the direction of travel won't produce the tire grab or other tendencies that a slightly crabbed landing will produce on a hard surface. If you do a lot of flying on grass and then transition back to a paved surface, you may find that bad habits have developed. Then again, you may not, but it's not uncommon. The phenomenon is somewhat the same as learning bad habits in a tricycle gear airplane, that show up when transitioning to a conventional gear (tailwheel) airplane. Same thing for grass to paved surfaces.