Are you packing the stones densely around the plant to create semi-continuous protective shield?
Densely packed could also deter gophers from emerging near the main stalk and chopping it off.
Thanks for your curiosity about this approach, Cristobal. My practice has been to densely pack the stones about 1' tall around the perimeter of the bed then randomly place the stones on the top surface of the bed. The goal is to place the top stones further away from the plants as the roots get established. I want airflow. The surrounding frame is a variation on the Zuni Waffle Garden. My waffles are much more curvy than the traditional beds.
The gophers have stayed out so far. I add new layers of stones as the edges submerge and some of the edges are as much as a foot underground.
Gathering stones for the garden is my favorite winter pastime. I hope this works for you!
P.S. Growers in my area frequently protect young grape vines with 2 curved pieces of hardware cloth (like a forward C and backward C) to form an overlapping circular barrier around the stem, above and underground: (
O). As the stem grows, the C's can be pulled apart. The mesh pieces are removed when the plant gets woody. This works very well for protecting young plants from rodents.