Choose those meant for freestanding and retaining walls, not walkway pavers. To calculate how many blocks you need, divide the area, in inches, of each wall by the area of the largest block's face. Add 10 percent to cover cuts and breakage.
A 50-pound bag covers 2 square feet at 3 inches deep
A 50-pound bag covers about 6 square feet at 1 inch deep. Drainage stone
Get enough to fill your planters to three courses from the top.
Masonry construction adhesive