Raised bed layout: sizes, paths and how many plants fit
Three numbers decide a raised bed: how far you can reach, how wide the paths are, and how deep the soil is. Get those right and the plant count follows from mature spacing.
The three numbers
| Dimension | Practical value | Why |
|---|---|---|
| Bed width | 1.2 m / 4 ft (reach from both sides); 60–75 cm / 2–2.5 ft against a wall | You should not step into the bed: walking on it compacts the soil. |
| Path width | Main path 1.2 m / 4 ft; between beds 60–90 cm / 2–3 ft | Two people passing, a wheelbarrow, and room to kneel. |
| Soil depth | 30 cm / 12 in for most vegetables; 20 cm for herbs and salad; 30–40 cm for carrots and parsnips | Root volume and moisture buffering. Deeper beds dry out more slowly in summer. |
Bed length is free: 2.4 m / 8 ft is common because lumber comes in that length and the bed stays walkable from both ends.
Worked example: a 4 × 8 ft bed
- Area: 4 × 8 = 32 sq ft (about 3 m²).
- Soil volume at 12 in deep: 32 × 1 = 32 cubic feet ≈ 0.9 m³. At 8 in deep: 16 cubic feet ≈ 0.45 m³.
- Plant count: divide the planted area by the area each plant needs (spacing²). Leaving a 30 cm path-side strip for access, about 26 sq ft is planted.
- Example planting: purple coneflower at 1.5 ft spacing takes 2.25 sq ft each → about 11 plants; English lavender at 2 ft takes 4 sq ft → about 6 plants; chives at 1 ft along the front edge take 1 sq ft → 8–10 along 8 ft.
Those counts come from the spacing table on the plant spacing chart; they assume a solid planting, so round down for paths or a focal shrub.
Orientation, sun and drainage
- Run the long axis east–west where you can, and put the tallest crops on the north side so they do not shade the rest.
- Site the bed where it gets the light your crops need: 6+ hours for fruiting vegetables, 3–6 for leafy crops and many herbs.
- Level the frame; a bed that sits low collects water. On clay, dig or loosen the ground below the bed so water can move.
- Line the bottom with cardboard if you are smothering grass, but do not seal it: drainage matters more than weed suppression.
Five mistakes that show up in the second season
- Beds wider than 4 ft: the middle gets compacted and weeded less.
- Paths under 60 cm: you cannot kneel between beds, so you stop using the far side.
- Filling with topsoil only: it settles and crusts. Use a mix with compost and coarse material.
- Overplanting at nursery spacing: the bed looks full in June and impenetrable in August. Space by mature width.
- No irrigation plan: a raised bed drains faster than the ground. Drip line or a soaker hose on a timer is the difference between a crop and a rescue.
FAQ
How wide should a raised bed be?
About 1.2 m (4 ft) if you reach from both sides, or 60–75 cm if it sits against a wall.
How deep should the soil be?
About 30 cm for most vegetables; 20 cm for herbs and salad; 30–40 cm for root crops.
How much soil does a 4 × 8 ft bed need?
At 30 cm deep, about 32 cubic feet (0.9 m³); at 20 cm, about 0.45 m³.
Related: plant spacing chart · yard survey checklist · render vs plan