I have several raised beds, each about 12' x 5' x 12'' deep. Sides are 2" x 6" cedar. Some beds have a tight plank bottom and some have a poly tarp bottom with drainage holes and anchored to the wooden sides. The beds sit on clayey rubble with cracked limestone 6" to 10" below. Big roots find their way around the outside perimeter of the beds not far below the surface. Smaller roots then find their way in by forcing themselves through the plank joints. They are not big but grow extensively in the soil. I am thinking that if I dig a small trench 4" x 4" around the outside of the cedars sides, fill it with salt pellets and cover these with soil then the roots will not attempt to pass though the salt saturated ground down to the limestone. Do people think this will work and will the salt find it's way up inside the beds and kill all growth?
