How Much Mulch for a Flower Bed?
Material needed
0.93 cubic yards
A typical foundation bed, 4 feet deep and 25 feet long, mulched 3 inches deep.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Bed area100 sq ft
- Depth3 in
- MaterialMulch
Material needed0.93 cubic yards
| Volume | 25 cu ft |
|---|---|
| Cubic yards | 0.93most yards sell in half yard steps |
| Order in half yards | 1 cu yd |
| 2 cu ft bags, if bagging it | 13 |
| Approximate weight | 741 lb (0.37 tons) |
The material list this produces
| Material, cubic yards | 1 |
|---|---|
| Landscape fabric, sq ft | 100 |
| Edging, linear ft | 40 |
Depth compared
Depth is the whole calculation. Two inches will not suppress weeds, six inches will suffocate roots.
| Depth | Material needed | Order in half yards |
|---|---|---|
| 2 in | 0.62 cubic yards | 1 cu yd |
| 3 in | 0.93 cubic yards | 1 cu yd |
| 4 in | 1.23 cubic yards | 1.5 cu yd |
| 6 in | 1.85 cubic yards | 2 cu yd |
What else matters here
Most foundation beds are between three and five feet deep and run the length of a wall, so a hundred square feet is the usual answer for one side of a house. Measure yours: beds curve, and a curved bed is close enough to its average width times its length.
In a planted bed, keep the mulch thinner right around each plant and full depth in the open areas between them. Three inches of bark against a perennial crown is how you lose perennials over a wet winter.
Refresh rather than replace. Bark mulch breaks down into the soil, which is the point, so most beds only need an inch or so topped up each spring. Stripping and replacing the whole depth every year both costs more and builds worse soil.
What this calculator assumes
- Three inches is the usual mulch depth. Two is thin and will not hold weeds down, four starts to smother shallow roots and holds water against trunks.
- Weights are approximate and vary with moisture: mulch about 800 lb per cubic yard, topsoil 2200, gravel 2800, sand 2700.
- Bagged material is sold in 2 cubic foot bags, and there are 13.5 of those in a cubic yard.
Questions people ask
How much mulch for a typical flower bed?
A 4 by 25 foot bed is 100 square feet, which is about 0.93 cubic yards or 13 two cubic foot bags at 3 inches deep.
How often should mulch be replaced?
Most beds only need an inch topped up each spring, since bark breaks down into the soil. A full strip and replace every year costs more and leaves poorer soil.
How do I measure a curved bed?
Average width times length is close enough for ordering. Mulch is sold in half yard steps, so precision past that buys you nothing.
The mulch and gravel calculator takes any dimensions you like and hands back the same list.