Mulch Material

Depth

Water Retention

Weed Control

Decomposition Rate

Tips for Using

compost

3 inches

good

fair

rapid

Mix with leaves or other mulch.

wood chips

2-4 inches

good

good

fairly slow

Can rob nitrogen if mixed into soil.

leaves

3 inches

fair

fair

slow; adds nitrogen

Adds nutrients; use whole or shred with mower.

grass clippings

1 inch max.

good if not matted

fair

rapid

Avoid grass treated with pesticides or herbicides; mix with leaves for thicker layers.

green cover crops

full height

good 

good

does not break down independently, needs to be tilled under

Rich in nitrogen.

evergreen boughs

several layers 

fair 

fair 

slow 

Good for erosion and insulation from wind; remove in spring. 

pine needles

1.5 inches

good

good

slow

Good for acid-loving plants (rhododendrons, azaleas, blueberries).

mixed bark

2-3 inches

good

good

slow

Replace every two years.

newspaper

4-6 sheets

good

best

rapid-lasts one season

Wet the paper & cover with another type of mulch to hold the paper in place (ink is not toxic).