Mulch is the highest-return thing you can do for your beds. It holds in moisture, smothers weeds, moderates soil temperature, and gives the whole landscape a finished look. But it only works at the right depth — and most people either spread it too thin to help or pile it so deep it does harm.
The magic number is three inches
For most beds, aim for a two-to-three-inch layer of mulch. Thinner than two inches and weeds push right through and the soil dries out. Thicker than three or four inches and you can suffocate roots and create a haven for pests and fungus.
Never pile mulch against tree trunks — the dreaded 'mulch volcano.' It traps moisture against the bark, invites rot and rodents, and slowly kills the tree. Pull mulch back a couple of inches from trunks and stems so they can breathe.
Estimating without doing geometry
Mulch is sold by the cubic yard, and one cubic yard covers about 100 square feet at three inches deep. That single fact is all you really need:
- Measure the rough length and width of each bed and multiply to get square feet.
- Add up all your beds.
- Divide the total by 100. That is roughly how many cubic yards you need at a proper three-inch depth.
So a property with 500 square feet of beds needs about five cubic yards. If you are only topping off existing mulch rather than starting bare, you can cut that estimate by a third to a half.
Bags or bulk?
Bagged mulch usually holds two cubic feet, so it takes about 13 to 14 bags to equal one cubic yard. For a bed or two, bags are convenient. Past three or four yards, bulk delivery is far cheaper and a lot less plastic to haul and stuff in the bin.
Which mulch, and when
Shredded hardwood is the Chicagoland workhorse — it knits together, stays put on slopes, and breaks down into the soil over time. Dyed mulches hold color longer if that matters to you. The best time to refresh is spring, after the soil has warmed and you have done your weeding, so you are sealing in a clean bed.
Refreshing mulch is satisfying work — and also heavy, dirty work that eats a Saturday. If you would rather skip the wheelbarrow, we will deliver and install it at the right depth, edged clean, in a single visit.