What Soil Goes in a Raised Garden Bed?
Fill raised beds with a loose, fertile blend — commonly about 60% screened topsoil and 40% compost, or a bagged raised-bed mix. Plain garden soil alone tends to compact in a bed, and pure compost shrinks and can be too rich.
Common raised-bed mixes
| Mix | What it is | Good for |
|---|---|---|
| Topsoil + compost (about 60/40) | Screened topsoil blended with finished compost | Large beds bought in bulk |
| Equal parts compost, peat or coir, and vermiculite | A light, soilless "square foot" style mix | Small beds, containers |
| Bagged raised-bed mix | Pre-blended product | Convenience for a few beds |
How deep?
Lettuce and herbs grow in 6–8 inches; most vegetables do well with 10–12 inches; carrots, potatoes and deep-rooted crops appreciate 18 inches or more. Below a raised bed, loosen the existing soil so roots can keep going down.
Saving soil in tall beds
Gardeners often fill the bottom of 24-inch beds with logs, branches and leaves (a hügelkultur-style layer) and put soil only in the top 12 inches. The wood breaks down over time, so expect the bed to sink and top it up yearly.
How much to buy
| Bed | Depth | Cubic feet | 1.5 cu ft bags |
|---|---|---|---|
| 4×8 ft | 12 in | 32 | 22 |
| 4×8 ft | 18 in | 48 | 32 |
| 3×6 ft | 12 in | 18 | 12 |
| 4×4 ft | 12 in | 16 | 11 |
Get exact numbers for your beds with the raised bed soil calculator.