What do you do?
Don't hesitate to call your real estate photographer and discuss the issue that you have. Tell him/her that the house is ready to be shot, but the lawn will probably need some retouching. Most of the time the photographer will be happy to do so. After all you are the customer and we are in the business to make you look good.
Is this a questionable practice?
I don't think so. It's grass and it will green when spring comes. It would be questionable if plants, and bushes were added, or if the color of the house was changed.
Real Estate Photography - Examples Real Estate Photography Services
Jody Moore - Real Estate Photographer
Blue Shirt Photography, LLC.