Idolaters planted groves about the temples and altars of their gods. Hereby God designed to take away whatsoever might bring their idolatry to remembrance, or occasion the reviving of it.
Related Commentaries of Deuteronomy 7:5
Deuteronomy 7:5
5 But thus shall ye deal with them; ye shall destroy their altars, and break down their images,a and cut down their groves, and burn their graven images with fire.