Mulch, Soil, and Compost

Amounts Needed

How to use this table: 

Step 1: Multiply length x width of area to be covered, to find total sq ft of area. Find the nearest number in the left column. To calculate space of round or triangular spaces, see page 2.

Step 2: Read across that line, to the column that displays the desired inches of mulch/soil/compost in its top row, to find the number of cubic yards of material needed.

Example:

Step 1: Area 50’ long x 20’ wide = 1000 square feet of area to cover.

Step 2: If desired depth = 3”, then 9 cubic yards of material is needed.

Note: 1 cubic yard = 27 cubic feet; 1 cubic yard = nine 3-cu-ft bags

Square feet to cover	Depth of Mulch/Soil/Compost in Inches
	2”	3”	4”	6”	8”	12”
50 ft2	¼ yd3	½ yd3	½ yd3	1 yd3	1+ yd3	2 yd3
100	½	1-	1+	2	2½	4
150	1	1½	2	3	4	6
200	1+	2	2½	3½	5	7½
250	1½	2½	3	4½	6	9
300	2	3	3½	5½	7½	11
350	2+	3½	4½	6½	9	13
400	2½	4	5	7½	10	15
450	3	4½	5½	8½	11	17
500	3+	4½	6	9	12	18½
550	3½	5	7	10	13½	20
600	3½	5½	7½	11	15	22
650	4	6	8	12	16	24
700	4+	6½	8½	13	17	26
750	4½	7	9½	14	18½	28
800	5+	7½	10	15	20	30
850	5	8	10½	15½	21	31
900	5½	8½	11	17	22	33
950	6	9	12	17½	23	35
1,000	6	9	12	18½	25	37

Common Mulches and Their Characteristics

Mulch Material	Characteristics
Organic matter:
Bark chips; wood chips	Attractive; long-lasting; decompose slowly; hinder water and air movement if too deep; color varies by species and age of material.
Grass clippings	May contain weed seeds; must replenish frequently as clippings decompose; may mat down when wet.
Leaves	Contain trace elements; some mat down and hinder water movement; can be tilled in to add organic matter to soil.
Pine needles	Light-weight; decompose slowly; attractive.
Hay	May contain too many weed seeds to be useful as a mulch; sometimes used in food gardens.
Straw	Used primarily in food gardens; apply 6-8″ of loose straw mulch to control weeds.
Salt marsh hay	Usually weed-free; long-lasting; used primarily in food gardens; more available near coast.
Peat moss	Weed-free; may mat down and hinder water penetration; nonrenewable resource.
Compost	Short-term mulch; adds nutrients to soil when tilled in; variable product depending on what raw materials were used to make the compost.
Plastic materials:
Black plastic	Retains soil moisture; prevents most weeds; warms soil; used primarily in food gardens.
Clear plastic	Heats soil; weeds grow underneath, but not effective at killing all weed seeds in Maine.
Landscape fabric	Woven fabrics control weeds when laid under layer of bark; can hinder water/air movement.
Other materials:
Shredded paper	Decomposes in one season; use 6-8″ of loose shredded paper to control weeds; newspaper strips stick together if watered periodically.
Decorative stone	Permanent; heavy; does not always provide good weed control.

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From the GardenPro Answer Book; revised and updated by Lois Berg Stack, Ornamental Horticulture Specialist, University of Maine Cooperative Extension.