Mulch vs Gravel vs Rock for Garden Beds: Which to Use
Three materials cover most garden beds: wood mulch, gravel (such as pea gravel), and decorative landscape rock. They behave differently, and their cost per square foot is very different from the cost per cubic yard, so compare quantities for your own bed. For a 20 × 10 ft (200 ft²) bed, the calculators give:
Part of the project planners: Planning a new lawn and garden beds and Waking the yard up for spring.
| Wood mulch | Gravel | Landscape rock | |
|---|---|---|---|
| Depth | 3 in | 2 in | 2 in |
| Amount to buy | 1.9 yd³ | 1.9 tons (1.4 yd³) | 1.4 yd³ (1.8 tons) |
Gravel and rock include the calculators' default 10% waste allowance. Open the mulch, gravel and landscape rock calculators to change the size or depth. Buying in bulk is usually much cheaper than bags above about a half cubic yard.
How they compare
- Wood mulch: feeds the soil as it breaks down, holds moisture and keeps roots cool, but has to be topped up every year or two and can float away in heavy rain.
- Gravel: does not rot or blow away, drains fast and suits paths, drip-irrigated plantings and dry climates. It does not improve the soil, and falling leaves are harder to clean out of it.
- Decorative rock: permanent and clean looking, but heavy to move, hot in strong sun and hard to dig through later. It is the hardest option to change your mind about.
- Weeds: a thick layer of any of them helps. Pull weeds early, and use fabric under stone rather than under mulch.
- Weight: a cubic yard of rock or gravel weighs well over a ton, so plan for the delivery and the wheelbarrow trips.
Choosing
For beds with plants that like moist, rich soil, use mulch. For a dry, sunny strip, a path or a bed beside the foundation, use gravel or rock. Many yards mix them: mulch in the beds and gravel on the paths. See the guides on how much mulch you need, and the lawn and garden beds planner for the order of work.
Frequently asked questions
Is mulch or rock better around plants?
Mulch suits beds with plants and shrubs, because it breaks down and feeds the soil. Rock and gravel suit dry, low-water plantings, paths and areas that should stay clear of organic matter.
Should I put landscape fabric under mulch?
Many gardeners skip it under mulch, because the mulch breaks down on top of it and weeds root in the top layer anyway. Under rock and gravel it helps keep the stone from sinking into the soil. Decide per bed.
Is it safe to put rock next to the house?
Stone keeps its form and does not feed insects the way wood mulch can, so many people leave a strip of gravel against the foundation. Keep any material below the siding and the vents.
How deep should mulch be?
Commonly 2 to 3 inches. Too thin lets weeds through and too thick can keep roots wet. Keep it from piling against tree trunks.
More guides
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and follow local building codes for anything structural.