Words you’ll hear at the yard: landscaping terms explained

Buying by volume and weight

Cubic yard (“a yard”)

When a landscape yard says “a yard” of mulch, soil or stone, it means a cubic yard: a box 3 ft long, 3 ft wide and 3 ft high, or 27 cubic feet. That is 13.5 bags of the common 2 cu ft size, or 9 bags of 3 cu ft. Spread 3 in deep, one cubic yard covers 108 sq ft — about a 10 × 11 ft bed. In metric, the unit is the cubic metre (m³), which is 1,000 litres and a little over 1.3 cubic yards.

To see the conversion on a real job, How much mulch for a 10×10 area works out to just under one cubic yard, and How many bags of mulch are in a cubic yard lists every bag size.

Bulk

Material sold loose, scooped by a loader and delivered by dump truck (or loaded into your own truck or trailer), rather than in bags. Mulch and soil are usually priced per cubic yard; stone and sand are often priced per ton. Bulk is cheaper per yard, but most yards add a delivery fee per truckload and many have a minimum order, so small jobs are often cheaper in bags. The bagged vs bulk guide shows how to find the break-even.

Density (tons per yard)

How much a cubic yard of a material weighs. It is the number that converts a volume (what you measure in the garden) into a weight (what a quarry or yard sells and what your truck can carry). Typical loose gravel is around 1.4 tons per cubic yard, topsoil roughly 1 to 1.4 tons depending on how wet it is, and wood mulch only a few hundred pounds. The calculators build in typical values, but your supplier’s own figure is better — the landscape material weight chart has the full list.

Loose vs compacted

Every figure a yard quotes is for loose material, as it sits in the pile. Once it is spread and tamped or rolled, it takes up less room. How much less depends on the material: clean, single-size stone such as #57 or pea gravel barely changes, while a dense-graded base like crusher run packs down a lot because its fine particles fill the gaps between the stones: a yard that weighs about 1.5 tons loose ends up around 1.9 tons per cubic yard once compacted (Wisconsin DOT research puts compacted dense-graded base at roughly 1.75–2.1), so you order about a quarter more loose stone than the compacted volume. That is why the stone calculators ask for the compacted depth you want and then add a compaction allowance for the material to work out what to order. Soil settles too, especially fluffy screened topsoil, which is why the topsoil calculator adds a settling allowance.

Stone and gravel

#57 stone

A clean crushed stone graded to a US standard size number (AASHTO M 43 / ASTM D448). No. 57 runs from about 1 in down to roughly 3/16 in (the No. 4 sieve), with most pieces between ½ and 1 in, and has little dust or fines. Because the pieces don’t fit tightly together, water drains straight through, which makes it the usual choice for drainage, under-slab and French-drain stone, and a common driveway top in many areas. It doesn’t pack into a hard surface on its own. Other numbers you’ll hear follow the same system: the smaller the number, the bigger the stone (#3 is roughly 1–2 in, used as a bottom driveway layer).

Crusher run

Crushed stone with everything from about ¾–1½ in chunks down to stone dust left in. Sold under many regional names — crusher run, dense-graded aggregate (DGA), road base, quarry process, “item 4”, CR-6 or a state spec number — it compacts into a hard, stable layer, which is why it goes under sheds, pavers and driveways. It does not drain like clean stone. See it at work in How much gravel for a 12×16 shed base and How much base and sand for a 12×16 paver patio.

Pea gravel and river rock

Both are naturally rounded stone rather than crushed. Pea gravel is small (roughly pea-sized) and comfortable underfoot, so it is used for paths, patios and play areas; river rock is larger and decorative. Rounded stone rolls rather than locking together, so it needs edging to stay put and makes a loose surface under tires.

Edge restraint

The border that stops pavers, gravel or mulch from creeping outward: plastic or aluminum paver edging spiked into the base, a concrete curb, or a soldier course of pavers set in concrete. Paver patios need a restraint on every side that isn’t already against a house wall or slab, or the joints open up and the edge pavers drift. The paver calculator works out the feet of restraint you need.

Lawns

Topdressing

Spreading a thin layer of compost or screened soil over existing grass — about ¼ in on established turf, per Penn State Extension, ideally raked in after core aeration. At ¼ in, 1,000 sq ft takes a bit under a cubic yard. It levels small dips and adds organic matter without smothering the grass. The worked example is How much compost to topdress a 1,000 sq ft lawn.

Overseeding

Sowing seed into an existing lawn to thicken it, rather than starting from bare soil. It uses a lower seeding rate than a new lawn because some grass is already there. In the South, “winter overseeding” means something different: sowing ryegrass into dormant bermuda for green color through winter. The grass seed calculator handles both; see How much grass seed to overseed 5,000 sq ft.

Pure live seed (PLS)

The share of a seed bag that is actually seed of the grass you want and will germinate: purity % × germination % (both are on the seed tag). Recommended seeding rates assume good seed; a lower PLS means spreading more bag weight to get the same number of live seeds.

N-P-K

The three numbers on every fertilizer bag, such as 24-0-6. They are percentages by weight: nitrogen (N), then phosphorus as phosphate (P₂O₅), then potassium as potash (K₂O), as the University of Minnesota Extension explains. A 50 lb bag of 24-0-6 holds 12 lb of nitrogen. Lawn rates are given in pounds of nitrogen per 1,000 sq ft, which is why the fertilizer calculator starts from the first number; How much 24-0-6 fertilizer for 5,000 sq ft shows the math.

CCE (calcium carbonate equivalent)

How strong a liming product is compared with pure calcium carbonate, which counts as 100%. Soil-test lime recommendations assume 100% CCE; if your bag says 80%, you need more of it. Penn State Extension’s rule: product needed = recommendation ÷ CCE × 100 — so 75 lb at 80% CCE becomes about 94 lb. The lime calculator does this for you.

Buffer pH

A second pH number on many soil-test reports, measured after the lab mixes your soil with a buffer solution. The ordinary (water) pH says how acid the soil is now; the buffer pH says how much reserve acidity it holds, which is what decides how much lime it takes to move. Two lawns at the same pH can need very different amounts. Ohio State’s lime equations turn the two numbers into a rate, and the lime calculator has that mode; if your lab gives its own lime recommendation, use it, because labs in different regions use different formulas.

Slow-release nitrogen

Nitrogen in a form that feeds the grass over weeks rather than days, listed on the bag as slowly available or water-insoluble nitrogen. It matters for how much you can put down at once: Purdue Extension suggests no more than 1 lb of quickly available nitrogen per 1,000 sq ft per feeding, and allows more when over half the nitrogen is slow-release.

Trees and beds

Drip line

The outer edge of a tree’s canopy — where rain drips off the outermost leaves. Many of the roots that take up water are out there, not at the trunk, which is why Penn State Extension suggests mulching as much of the area as possible, preferably out to the drip line, and keeping mulch pulled back a few inches from the trunk itself. See How much mulch for a 6 ft tree ring.

Using these words when you order

• Say the volume and the material together: “2 cubic yards of shredded hardwood mulch, delivered” or “4 tons of crusher run”.
• Ask how they sell it (by the yard or the ton), in what steps (half-yard, half-ton), the minimum delivery and the fee per truckload.
• For base under pavers or a shed, say it will be compacted — a good yard will check your quantity against the compacted depth.
• For stone, ask what their product is called locally; crusher run, DGA and road base can be the same thing or slightly different blends.