Shredded Mulch for Beds and Tree Rings on Thin, Stony Ground

Most beds on a property here sit in a shallow skin of soil over stony till, with ledge somewhere underneath it. That soil dries out between rains faster than the plants in it would like, and it grows weeds enthusiastically in the gaps.

Shredded mulch is the cheapest fix for both. Shredded hardwood in consistent medium shreds, natural brown, laid 2 to 4 inches deep over the bed once planting is done.

Does mulch do anything useful on ground this stony?

More than it does on deep soil, in fact, because the thin stuff is what dries hardest.

The layer shades the soil surface, so less water leaves by evaporation between rains. It evens out root-zone temperature through the swings that come with a hard freeze-thaw climate. It keeps light off weed seed, which is most of what stops weeds germinating. And it breaks down over a few seasons into the bed, which on stony ground is the only realistic way to build any soil at all.

The shreds knit together into a mat rather than sitting as loose chips, which is why they stay put in a downpour and a wind that would scatter nuggets.

Is it worth putting down in spring, or waiting for fall?

Spring, for most beds. Once the frost is out, the ground has drained and planting is finished, which in southern towns is usually late in mud season and later still in the North Country and up in the mountains.

Go too early and you are mulching cold, wet soil, which keeps it cold and wet. Let the ground warm first.

A fall application is a different job, done after the ground has chilled rather than before, to steady the freeze-thaw cycling that pushes shallow-rooted plants out of the ground over winter. Both are reasonable. Doing both in one year is usually too much material.

How deep does shredded mulch go over soil this thin?

Two to four inches, which is what the material data for this product gives, and there is a reason for each end of that.

Under two inches, light reaches the soil and the weeds arrive. Over four, the layer holds water against the surface and air out of it, and roots start living in the mulch instead of the soil.

Keep it off the stems. A ring of mulch piled against a trunk holds moisture on bark that wants to be dry and invites mice to spend the winter chewing on it. Pull it back a couple of inches from the trunk and leave the flare showing.

Top up rather than rebuilding. A bed that had three inches last year has broken down to perhaps two, so it needs an inch, not another three.

Can I move eight yards with a fork and a wheelbarrow?

Yes, and it is the least unpleasant bulk material to move. A cubic yard of it runs about 600 lb on this site's published figures, which is roughly 0.30 tons, so a wheelbarrow of mulch is a quarter the weight of a wheelbarrow of stone.

A mulch fork beats a shovel by a wide margin. Reckon on a long morning for four or five yards with one person, less with two and a tarp run.

Where it lands matters more than usual, because mulch stains a driveway and kills grass under a pile left for a week. Put it on a tarp on the hard surface closest to the beds, and plan to be finished with it inside a couple of days.

What about the downspout corner, the wall backfill and the shoreline?

Three jobs it gets asked to do and should not.

A downspout splash area. Concentrated roof water floats mulch and carries it across the lawn in the first hard rain. Use this instead: #57 stone or drain rock at the outfall, which stays where it is put and lets the water down into the ground.

Retaining wall backfill. Organic material behind a wall rots down, holds water against the blocks and settles, which is three problems for the price of one. Use this instead: 3/4 inch crushed stone against the wall face, draining to the bottom.

A pond or shoreline edge. Mulch floats. It ends up in the water, along with everything it releases as it breaks down. Use this instead: river rock for a quiet edge, or large river rock where wave action is at work. Shoreline work is regulated, so check with the town first.

How many yards for 340 square feet of bed and six tree rings?

A hypothetical spring order, at 3 inches.

Beds, 340 sq ft total

• 340 x 3 / 12 = 85 cu ft
• 85 / 27 = 3.15 cu yd

Six tree rings, 5 ft across, with a 1 ft gap left at each trunk

• Each ring: 0.7854 x 5 x 5 = 19.6 sq ft, minus 0.7854 x 1 x 1 = 0.8 sq ft, so 18.8 sq ft
• 18.8 x 6 rings = 113 sq ft
• 113 x 3 / 12 = 28.3 cu ft
• 28.3 / 27 = 1.05 cu yd

Total: 4.2 cubic yards, which is about 1.3 tons at roughly 0.30 tons per yard. Order it by the yard, since that is how it is spread and the weight figure is only useful for knowing what the truck is carrying.

For coverage at other depths: one cubic yard covers about 162 square feet at 2 inches, 108 at 3 inches and 81 at 4 inches. Awkward bed shapes go through the mulch calculator.

Does it need fabric under it, or soil worked in first?

Fabric under mulch is a decision that ages badly in a planted bed. Mulch breaks down on top of it into a seed bed, weeds root in that layer, and now you are weeding a bed you cannot cultivate. In a bed with nothing growing in it, fabric is reasonable. In a planted one, skip it and rely on depth.

Soil is the other question. Mulch is a topping, not an amendment, so if the bed needs better soil that goes in first as garden soil or screened loam, worked in before the mulch goes over the top.

And it never gets compacted. Rake it level, leave it fluffed, and let the first rain settle it.

Measure the beds, work out the yards, then choose a quantity and a delivery date here. Delivery is arranged at checkout by ZIP code, and the truck needs room to back and a clear spot to tip.