Is grass a heterotroph?

It's a heterotroph.

Wheat grass is an autotroph. This organism does not have to rely on obtaining food from outside. They synthesize their own nutrients and energy.

A heterotroph is any organism that requires organic subtrates in order to survive. Basically, a heterotroph is a consumer which must eat other animals and cannot produce its own food.

A herbacious plant with tiny stems that are only a few milimeters in height and long, slender leaves. It contains no branches like trees, shrubs and forbs do, and its growth points are very close to...

an autotroph is an organism capable of synthesizing its own food from inorganic substances, using light or chemical energy.