Beds prepped first, then mulched to depth

What goes under the mulch matters

Mulch is the last step, not the first one. Before a single bag or scoop goes down, the bed gets cleared: old shredded material that has matted into a crust, leaves packed against the crowns of the shrubs, whatever weeds are already up, and any rock or fabric somebody put in years ago and gave up on. Then the bed gets leveled so water runs where you want it. Skip that and you are just hiding the problem under something browner.

The edge is the part people notice without knowing why. A bed with a clean cut line, spade depth, holds mulch inside it instead of letting the first hard rain carry it out onto the turf and the driveway. On the newer streets around Smyrna the builder beds are usually a shallow scrape with a plastic strip pushed in, and the strip heaves out of the ground the first winter. We cut a trench edge instead. It costs a little more time and it stays put.

Elizabeth Earls wrote about the beds at her place: "He cleared out our beds, took away large rock and leveled our beds to make it easier to plant and fill in the future." That is the order the work goes in. When it is done right the mulch sits below the top of the edge, the shrub trunks are still visible at the base, the bed line follows a shape you could mow along, and nothing is piled against the house.

• Old matted mulch pulled before new goes down
• Beds leveled so water runs off right
• Spade-cut trench edge, not plastic strip
• Weeds pulled at the root, not buried
• Trunks and stems left clear of mulch

Depth is where most mulch jobs fail

Thin mulch looks fine on the day and does nothing after that. Sunlight still reaches the soil, so weed seed germinates through it by the second month, and the ground dries out just as fast as bare dirt in a July stretch with no rain. Too deep is its own problem: water beads off the top and never gets to the root ball, and the bottom layer goes sour and matted. The depth that works sits between those, measured across the bed, not guessed at from the truck.

Beds that get topped every spring without anything coming off build up a hard layer underneath. Water runs across it like a roof. You can dig into a bed like that and find dry soil under four fingers of old material, with the plants sitting in a bathtub rim that fills and drains at the wrong times. When we find that, the old layer gets broken up or hauled off before anything new lands on it.

Mulch settles. Shredded hardwood knits together and drops after the first few rains, so a bed that measured right the day it went in reads shallow by midsummer, which is why the depth goes down with settling in mind. Color fades too. The sun here bleaches the top layer well before the mulch is actually spent, and a lot of people replace perfectly good material because of how it looks. Turning the top and adding a light course is often the honest answer.

What clay does to a mulched bed

Most of the newer housing around Smyrna and La Vergne sits on graded clay. The pad gets scraped, the topsoil goes somewhere else, sod goes down over what is left, and the beds along the foundation get filled with a thin skim of soil and a row of shrubs. Clay holds water at the bottom of that bed and sheds it off the top. Mulch on a bed like that has to work with the grade instead of against it, or spring rain moves it in one afternoon.

Washouts have a cause and it is usually a downspout dumping straight into the bed, or a bed that runs downhill toward the drive with nothing to stop it. Piling more mulch on top of that is money going down the gutter every storm. The fix is upstream: get the water carried past the bed, cut the edge deep enough on the low side, and on a real slope use a coarser material that locks instead of floating. Fine mulch on a slope ends up in the street.

The older lots tell a different story. Big oaks, shade most of the day, beds that were dug in around the trunks a long time ago and have crept out since. Under mature trees the soil is full of surface roots, so a bed there gets hand worked rather than turned over, and the mulch goes on light near the flare. Leaf fall matters too: an oak bed collects a mat of wet leaves every fall, and if that goes under fresh mulch it rots into a lid.

Mulch against the house and around trunks

Two places mulch should never be piled: against the siding or brick, and up the trunk of a tree. Foundation beds on the newer builds sit high already, and when mulch goes above the brick weep holes or up onto the siding you have put damp organic material in permanent contact with the house. That is a moisture problem and a termite invitation in a state where termites are a normal part of owning a home. The mulch line stops short and stays short.

The cone of mulch heaped against a young maple trunk is the most common thing we undo. Bark that stays wet softens, and roots that should head out into the soil circle up into the mulch instead and eventually strangle the tree. It takes years to kill something that way, which is why nobody connects the two. Pull the mulch back off the flare so you can see where the trunk widens and meets the ground, and keep the ring flat instead of mounded.

Weed fabric under mulch is the other thing worth arguing about. It buys a season or two, then the mulch on top breaks down into soil and weeds root in that layer above the fabric, where they pull harder because the fabric grabs the root and tears. Meanwhile the fabric keeps the mulch from feeding the soil underneath, which was half the point of putting it there. Beds in a humid summer want to breathe, so most of the time the fabric comes out and does not go back.