Formula
Same volume formula as soil: length × width × depth ÷ 12 = cubic feet. At 3 inches, 1 cubic yard (27 cubic feet) covers 108 square feet. Example: 10 ft × 10 ft at 3 in = 25 cubic feet, just under 1 cubic yard.
Common mistakes
- Mulch volcanoes: do not pile mulch against tree trunks or plant stems — keep it a few inches clear.
- Too deep is also a problem: more than 4 inches can suffocate roots and stay too wet.