Introduction
Walk into any garden center and the bag wall is confusing: garden soil, raised bed mix, topsoil, potting mix, compost, manure — all in similar bags at wildly different prices. Choosing wrong is the most expensive mistake in bed building, because bad fill costs you a season of growth plus a re-do. The Garden Soil Calculator tells you how much material you need; this guide tells you which material to buy.
Below is a ranked breakdown of every common option — what it is, what it costs in typical ranges, where it performs, and where it fails — plus the amendments worth buying and the ones you can skip.
Garden Soil / Raised Bed Mix (Best Default)
A manufactured blend of screened topsoil, composted organics, and mineral amendments, engineered to hold moisture, drain, and feed plants. Bagged 1.5 ft³ bags typically run $4–8 each; bulk yards sell it at $30–60/yd³. This is the no-thinking-required choice: fill the bed, plant, mulch. Quality varies by brand — look for a list of actual ingredients (composted bark, compost, perlite) rather than vague “forest products.”
50/50 Topsoil-Compost Mix (Best DIY Blend)
Half screened topsoil, half finished compost, mixed on a tarp or in the bed. Performance rivals bagged blends at lower cost when both ingredients are good quality — bulk topsoil is often $20–40/yd³ and bulk compost $25–50/yd³, so a 50/50 blend lands around $25–45/yd³. The risk is quality control: inspect both ingredients before the truck dumps them. This is the blend the pro tips guide recommends for budget builds.
Plain Topsoil (Acceptable With Amendment)
Screened native soil with no added organic matter. Cheap in bulk ($20–40/yd³ typical) but a lottery: it can be excellent loam or heavy clay, and it is often weedy. Never plant into it unamended — blend in compost at roughly 1 part compost to 2–3 parts topsoil and expect a weaker first season. Fine as a base layer under quality blend in deep beds.
Compost (Amendment, Not Fill)
Compost is the best soil improver that exists and a terrible fill material. Used at 2–3 inches (5–7.5 cm) worked into the top 6–8 inches (15–20 cm), it transforms mediocre soil. Used at 100% fill, it collapses as it decomposes and waterlogs. Budget roughly 0.77 yd³ of compost to amend a 10 × 10 ft area 2.5 inches deep — the classic mistake of filling with pure compost costs more than buying proper blend in the first place.
Potting Mix (Containers Only)
Soilless, light, sterile, fast-draining — perfect for pots, wrong for beds. It dries too quickly at bed scale, compacts oddly, and costs far more per cubic yard than garden soil. Use it for planters under ~20 gallons (75 L); anything bigger gets garden soil blend.
Subsoil and “Fill Dirt” (Avoid)
The dead layer from below the topsoil: low organic matter, often clay, sometimes contaminated on urban sites. Sold cheaply because it is nearly worthless for growing. No amount of surface amendment fixes a bed filled with subsoil in its first year. If a supplier cannot describe what is in their “garden soil,” assume the worst.
Amendments Worth Buying
| Amendment | What it does | Typical use |
|---|---|---|
| Perlite or pumice | Improves drainage and aeration | 1–2 bags per 4×8 bed in heavy blends |
| Composted manure | Slow-release nitrogen and organic matter | Top-dress 1–2 in yearly |
| Lime (pelletized) | Raises pH in acidic soils | Per soil test only |
| Coarse sand | Loosens heavy clay (with compost, never alone) | Amending native clay beds |
Skip: “moisture crystals,” expensive mycorrhizae inoculants for ordinary beds (compost provides biology free), and fertilizer spikes — a balanced granular fertilizer per the label is cheaper and more even. If you are amending native ground rather than filling beds, see the estimating guide for amendment volume math.
How to Judge Bulk Soil Before It Is Dumped
When the truck arrives — or better, when you visit the yard — inspect before you accept. Good garden soil is dark brown to black, crumbly, and smells earthy; it should hold together loosely when squeezed and break apart easily. Reject loads that are gray or pale (subsoil), smell sour or like chemicals, contain visible trash, glass, or large undecomposed wood chunks, or feel like pottery clay when wet. Ask the yard for the blend recipe: a reputable supplier names the components and their ratios without hesitation.
Moisture matters at delivery. Soil delivered soaking wet after rain weighs significantly more — pushing the top of the 75–100 lb/ft³ range — and clumps badly when spread. If you can choose, schedule delivery for a dry stretch; if the pile arrives wet, let it dry a day before spreading. A yard that delivers in the rain without mentioning it is telling you something about their service. These inspection habits are what separate the pro approach from the hope-for-the-best approach, and they cost nothing.
Storing Leftover Soil
Over-ordering slightly is correct practice, so plan for leftovers: keep extra soil in a covered pile on a tarp, or in the opened bags folded shut and stored out of direct sun. Uncovered piles grow weeds within weeks and lose nitrogen to rain leaching; a $10 tarp preserves a $50 half-yard. Leftover blend is perfect for fall top-dressing, filling settled beds, or next spring’s containers — it does not go bad, it just needs covering.
Related Guides
- Complete Guide — materials in the context of the full project.
- Cost Guide — what each option costs per cubic yard.
- Common Mistakes — the material errors to avoid.
- Pro Tips — filling and layering techniques.
- FAQ — quick material questions answered.
Get Your Number
Once you have chosen your blend, get the exact volume from the Garden Soil Calculator, add 10–15% for settling, and quote suppliers per cubic yard.
Disclaimer: Calculator results are planning estimates based on the dimensions you enter. Actual material requirements vary with product density, moisture content, and settling. Verify quantities with your supplier and consult a licensed professional for drainage or code-related decisions.
