Soil & Mulch

Soil and mulch are sold in two unrelated units, which is why they are hard to compare. Potting mixes list in quarts, running 4 to 950 here. Bulk soil and mulch list in cubic feet. One cubic foot is about 25.7 dry quarts, and nothing on the bag says so.

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Quarts, Cubic Feet and How to Compare Them

Potting mix is bagged in quarts and bulk material in cubic feet, and the conversion is the first thing worth knowing. One cubic foot holds roughly 25.7 dry quarts, so a 2 cubic foot bag and a 50 quart bag are close to the same thing at very different shelf prices.

Convert before comparing.

Volumes here run 4 to 950 quarts and 0.75 to 60 cubic feet, with 1 cubic foot the most common bulk size and 8 quarts the most common bagged one.

Potting Mix, Garden Soil and Compost

The three are not interchangeable and the bags look alike. Potting mix is light and drains fast, built for containers. Garden soil is heavier and meant to be dug into ground. Compost is an amendment rather than a growing medium.

Potting mix in a raised bed drains too fast and costs several times what it should at that volume. Garden soil in a container compacts and holds water, which is the more common of the two mistakes.

Organic and Certified Mixes

35 of the listings here state organic, which is the highest share of any attribute in the collection. Miracle-Gro at 22 listings and Back to the Roots at 14 carry most of the branded range, with Hoffman covering the specialist mixes.

Organic on a soil bag describes the inputs rather than a certification in every case, so the specific claim on the bag is worth reading where it matters.

Mulch Types and Coverage

Mulch is bought by area rather than volume, and the arithmetic is simple: one cubic foot covers about 6 square feet at 2 inches deep. A 1.5 cubic foot bag therefore covers roughly 9 square feet.

Bark, straw and rubber all appear here. Straw breaks down in a season and feeds the bed, bark lasts two or three, and rubber does not break down at all, which is a benefit or a problem depending on whether the bed is permanent.

Bulk pallets exist for large jobs.

Soil for Beds and Containers

A raised bed at 4 by 8 feet and 12 inches deep takes about 32 cubic feet, which is 21 bags at the common 1.5 cubic foot size. Container growing in pots and planters runs far smaller, and a 16-inch pot takes under 2 cubic feet.

Volumes Compared

PackVolumeFillsCovers at 2 in
8 quart bag0.31 cu ftOne 10 in potAbout 2 sq ft
16 quart bag0.62 cu ftOne 14 in potAbout 4 sq ft
1 cu ft bag25.7 quartsTwo 14 in potsAbout 6 sq ft
1.5 cu ft bag38.6 quartsOne 20 in planterAbout 9 sq ft
2 cu ft bag51.4 quartsHalf a grow boxAbout 12 sq ft

Soil & Mulch Questions

How many quarts are in a cubic foot?

About 25.7 dry quarts. That conversion is the only way to compare a bagged potting mix against a bulk soil or mulch bag, since the two use different units.

Can I use potting mix in a raised bed?

You can, but it drains too fast at that depth and costs several times what bulk soil does per cubic foot. Garden soil or a bed mix suits the volume better.

How much mulch covers a bed?

One cubic foot covers about 6 square feet at 2 inches deep, so a 1.5 cubic foot bag covers roughly 9 square feet.

Which mulch lasts longest?

Rubber does not break down at all, bark lasts two or three seasons, and straw breaks down within one. Straw feeds the bed as it goes.

Does organic mean certified?

Not always. On soil bags it often describes the inputs rather than a certification, so read the specific claim where it matters.