[concretegurl]

My pupmill rescue hated grass. Its foreign different and scary.

Try dog shoes.
Alldogboots.com

It could also be grass holds scent, I'd try shoes first.

It took about 5a months of confidence building to get Scoobers to walk on grass and willingly...now he rolls in it you'd never lnow there was a time I jad to make a dog walk in the yard