Buying soil and mulch by the yard
Landscaping materials are the one part of a building job where the unit changes underneath you. The same cubic yard of mulch is sold loose by the yard, bagged by the two cubic feet, and delivered by the ton, and the three prices are almost impossible to compare in your head.
The volume is easy — area times depth, like everything else. What is worth working out before you order is which form to buy it in, and how deep to spread it.
How deep, and why it matters more than the area
Depth is the number people guess at, and it is the one the whole order scales with. Doubling the depth doubles the cost; being a foot out on the length of a bed barely registers.
Mulch goes on at two to three inches. Less than two and weeds come through, which defeats the point. More than four and you start smothering roots and holding water against stems, particularly on shrubs. Three inches is the usual answer for a new bed and two for topping up an existing one.
Topsoil for a new bed wants four to six inches to be worth doing, and for a lawn repair two to three. Gravel paths run three to four inches, and a gravel base under a slab or paving is four inches compacted, which is more than four inches loose.
A twenty by ten bed at three inches of mulch is fifty-two and a half cubic feet — just under two cubic yards, or twenty-seven of the two-cubic-foot bags.
20 ft x 10 ft = 200 sq ft
200 x 3 in (0.25 ft) = 50 cu ft, +5% waste = 52.5
52.5 / 27 = 1.94 cubic yards
As bags: 27 x 2 cu ft
Work it out: Mulch Calculator →
Where bags stop being sensible
The crossover is around three cubic yards. Below that, bags usually win once delivery is priced in, and they are far easier to handle if the bed is at the back of a house with no vehicle access.
Above it the arithmetic turns sharply. Three cubic yards is eighty-one cubic feet, which is forty-one two-cubic-foot bags, and each of those has to be lifted twice — once into a car and once out of it — before anything reaches the garden. Loose delivery is tipped on the drive in one movement.
The other thing bags cost you is the bags. Forty-one plastic sacks is a real disposal problem and a genuinely irritating end to a good afternoon.
Work it out: Topsoil Calculator →
Tonnage is an estimate, always
Bulk material is often quoted by weight rather than volume, so the volume has to go through a density — and that density moves with moisture. The same topsoil weighs meaningfully more after a wet week than a dry one, and neither figure is wrong.
That is why any tonnage on a landscaping quote is a figure to order against rather than a promise. Three cubic yards of topsoil is somewhere around three and a half short tons, and the honest version of that sentence has the word "around" in it.
Loose material also settles. A yard tipped on the drive occupies more space than the same yard once it has been spread, walked on and rained on, which is one of the reasons a five per cent allowance is worth adding even on a job with no cutting waste in it at all.
Lawns: sod is perishable, seed is not
Sod is the one material here with a shelf life measured in hours. It is cut, rolled and delivered alive, and it wants laying within a day. Order it for the day the ground is ready rather than the day you plan to start clearing, because a pallet sitting rolled up in August is a pallet of dead grass.
A forty by thirty lawn is 1,200 square feet, which with five per cent for offcuts round curves is 126 rolls or three pallets. The same lawn from seed is about three and a half pounds at a typical rate — a fraction of the cost, and several months rather than an afternoon.
Five per cent covers the offcuts on a rectangular lawn. A lawn with island beds cut into it wastes considerably more, because every curve is a cut and most of what comes off a curve is unusable.
Questions
How deep should mulch be?
Two to three inches. Under two and weeds push through; over four and you start holding damp against stems and smothering shallow roots. Three for a new bed, two to top up an existing one.
How many bags of mulch in a cubic yard?
Thirteen and a half of the two cubic foot bags, since a cubic yard is twenty-seven cubic feet. Most people round to fourteen, and most people find that carrying fourteen bags is the moment bulk delivery starts to appeal.
Is bulk delivery cheaper than bags?
Past about three cubic yards, almost always — and the labour difference is larger than the price difference. Below that, bags usually win once delivery is priced in.
Why does the quote give a weight rather than a volume?
Because bulk aggregate and soil are sold by the ton. The conversion runs through a density that changes with moisture, so the tonnage is an estimate to order against rather than an exact figure.
How much topsoil for a new bed?
Four to six inches to be worth doing. A twenty by ten bed at four inches is about two and a half cubic yards.
How long can sod sit before I lay it?
About a day, less in hot weather. It is cut alive and rolled, and rolled sod heats up in the middle of the pallet. Have the ground prepared before it arrives.