Project guide
Rock ground cover
Rock does not rot, so it never needs redoing. It also never feeds the soil, and it moves heat around in ways bark does not.
- TimeA day for a front bed, most of it moving weight
- DifficultyEasy to do, heavy to carry
How much rock do I need to cover a bed?
- River rock, 3/4" at 3 inches: one cubic yard covers about 108 square feet at 3 inches, so 300 square feet takes about 3 cubic yards (roughly 3.9 tons).
- Crushed rock, 1-1/2" at 3 inches: one cubic yard covers about 108 square feet at 3 inches, so 300 square feet takes about 3 cubic yards (roughly 3.9 tons).
Work out how much river rock, 3/4" I need …and the crushed rock, 1-1/2"
What the job involves
Clearing and edging the bed, choosing a stone size, and spreading it to an even depth. Most yards sell rock by the ton rather than the cubic yard, so the calculator answers in whichever unit the yards near you use. None of the work is difficult; all of it is heavy.
What you need, and roughly how much
River rock, 3/4"
The ground cover
3 inches ground cover in beds
Gravel and rock work as mulches, most of them at 3 inches, within a range of 1 to 4 inches. Not every extension service agrees: one puts stone far shallower. Size decides as much as depth does: the benefits people actually want from stone, holding moisture in and keeping weed seedlings down, come from stone smaller than this, and larger sizes give landscape interest instead.
One cubic yard covers about 108 square feet at 3 inches, so 300 square feet takes about 3 cubic yards (roughly 3.9 tons).
Good for: Landscape plantings. Inorganic mulches like pea gravel are a good choice around trees, shrubs and perennials, and pea gravel improves how water gets into the soil in short, hard downpours. Not for: A bed you are trying to improve. Where soil improvement is the objective, an organic mulch that breaks down is the choice, and rock is the opposite trade: no maintenance, and no contribution.
Does the same job at this layer: Crushed rock, 3/4", Pea gravel.
3 listed yards publish a price for this.
How much river rock, 3/4" for my area? See the yards near me
Crushed rock, 1-1/2"
The bigger, angular option
3 inches ground cover in beds
Crushed rock is angular, so it keys together and holds a slope where a rounded stone rolls off it. This size goes down at 3 inches, and the bottom of its range is geometry rather than advice, because a stone cannot be laid shallower than the stone is thick. It is further still from the size that suppresses weeds, so buy it for how it looks and how it stays put, not as a mulch.
One cubic yard covers about 108 square feet at 3 inches, so 300 square feet takes about 3 cubic yards (roughly 3.9 tons).
Good for: Slopes, drip lines and the strip beside a drive, where a rounded stone travels. Fractured stone resists movement under load in a way rounded stone does not. Not for: Anywhere the point is holding moisture in and keeping weed seedlings down. That benefit comes from stone well below this size.
Does the same job at this layer: River rock, 1-1/2".
4 listed yards publish a price for this.
How much crushed rock, 1-1/2" for my area? See the yards near me
What else you will need
- A steel or masonry edge. Rock migrates into a lawn and then into a mower. Not sold here; a builders' merchant carries it.
- A leaf blower or a springbok rake, for the job bark never asks for: getting leaf litter out of stone every autumn.
- A barrow you trust and a plank if the run crosses grass.
- Somewhere for the pile to land. Rock is delivered by weight, and the pile is smaller and much heavier than people expect.
How to do it
- Clear the bed, roots and all. Anything left under stone stays there for years.
- Set a hard edge before anything goes in, so the rock stays in the bed and the lawn stays out.
- Spread the smaller stone to an even 3 inches, working out of the barrow with a fork rather than tipping and raking.
- Where the bigger stone is going in, spread it to 3 inches and let it find its own bed rather than raking it flat.
- Keep it back from stems and trunks the way you would with bark, so nothing sits wet against bark.
- Blow or rake the leaf litter off each autumn, or you spend next spring weeding the layer that collected on top.
Common mistakes
Laying fabric under it
The same fact sheet that gives the depth says correctly applied mulch does not need landscape fabric, that woven fabric clogs until it does what plastic does, and that weeds germinate on top of it and root through it anyway.
Choosing the stone from a photograph
Water conservation and weed suppression come from stone smaller than most decorative rock. Larger sizes are a different category entirely: landscape interest. Decide which of the two you are buying before you pick a colour.
Running it up against a wall you care about
Gravel moves more heat into what is under and beside it than wood chips do. Buildings and utilities are the ones to watch, and it can push tender plants into growth too early in spring.
Going deeper because it looks thin when it is dry
Depth is not the lever it appears to be. More is not better, and a cover that is too deep stops water and air reaching the soil. Stay inside 1 to 4 inches.
Expecting it to be permanent and invisible
Rock does not break down, which is the whole argument for it. What lands on top of it does. Leaf litter left in stone becomes exactly the seedbed the stone was bought to prevent, and the mulches that harbour trouble are the ones left to sit.
Work out how much
Add your area. The depth is already filled in.
Yards near you that carry it
585 listed yards carry rock. Set your area and the nearest come first, by distance and never by price. Every yard, by state · River rock, 3/4" prices · Crushed rock, 1-1/2" prices