🌳How much mulch does a ring around a tree need?

Four 2-cubic-foot bags for a 6-foot ring at 3 inches deep. A 3-foot ring takes one bag, a 4-foot ring two, an 8-foot ring seven, and a 10-foot ring eleven. Bag counts always round up, because half a bag of mulch is not something you can buy.

As wide as you can live with, and at least out to the drip line for a young tree — roughly 3 feet of ring for every inch of trunk diameter is a common rule. The practical minimum is wide enough that a mower and a strimmer never touch the bark, because mechanical damage at the collar is the other main way trees are lost in gardens.

Two to four inches, with three as the default. Below two it does not suppress weeds or hold moisture; above four it starts to restrict oxygen to the roots and can shed water rather than let it through. Every figure here assumes even depth across the ring and nothing at all against the trunk.

It is mulch mounded up the trunk in a cone. The bark above the root flare is not adapted to constant moisture, so it stays wet, decays, and lets in disease; the tree may also grow roots up into the mulch that later circle and strangle the trunk. It is the single most common mulching mistake and it kills trees slowly enough that the cause is rarely connected to the effect.

Three to six inches of bare ground all round, so the root flare — the point where the trunk widens into the roots — stays visible. If you cannot see the flare, there is too much mulch. This calculator subtracts the gap from the area rather than ignoring it, so the numbers match what you will actually lay.

Not usually — measure what is there and top up to depth instead. If the existing layer is already 3 inches, adding more takes you past the useful range and towards the airless end. If it has matted into a crust that water runs off, break it up with a rake before topping up; that crust is more likely with fine-shredded mulch than with bark nuggets.