Reviewed by Specialty Soils Updated August 21, 2026
For many tree and shrub beds, approximately 3 inches is a useful target for screened bark mulch. When refreshing, calculate only the missing depth.
Measure what is already there
If the bed has about 2 inches and the desired finished depth is 3 inches, add about 1 inch—not another full 3-inch layer.
Protect trunks and stems
Keep mulch away from tree trunks and root flares. Do not continually pile material against woody stems.
Calculate the additional layer
The mulch calculator supports new installation and refresh planning. Desired depth minus existing depth equals additional depth.
Turn the guide into a mulch plan
Choose the surface material, measure only the depth needed and plan bulk handling.
Sources & references
General horticultural guidance is supported by the following authoritative resources. Specialty Soils product statements and labeled company observations are first-party information.