Everything you need to build and fill a raised bed that will actually produce — from choosing the right size and materials to getting the soil mix dialed in. Includes a complete materials list and cost breakdown.
A standard 4×8 foot raised bed, 12 inches deep, costs $75–$200 for lumber and hardware plus $80–$150 for soil. Build time: 1–2 hours. No special tools needed beyond a drill and a saw.
4 feet wide maximum — you need to reach the center from either side without stepping in the soil. 8 feet long is the most common. 6, 10, and 12 foot lengths also work well.
Height: 12 inches minimum for most vegetables, 18–24 inches for root crops or if building on concrete or poor soil. Width matters more than length — never go wider than 4 feet.
| Bed Size | Soil (cu ft) | Soil (cu yd) |
|---|---|---|
| 3 × 6 ft × 12" | 18 | 0.67 |
| 4 × 4 ft × 12" | 16 | 0.59 |
| 4 × 8 ft × 12" | 32 | 1.19 |
| 4 × 8 ft × 18" | 48 | 1.78 |
| 4 × 12 ft × 12" | 48 | 1.78 |
| 4 × 8 ft × 24" | 64 | 2.37 |
Use our Garden Bed Soil Calculator to get the exact soil volume for your bed dimensions.
| Material | Cost / 4×8 Bed | Lifespan |
|---|---|---|
| Cedar (2×12) | $120–$200 | 10–15 years |
| Douglas Fir (2×12) | $60–$100 | 3–5 years |
| Pressure-treated (2×12) | $70–$120 | 15–20 years |
| Redwood (2×12) | $150–$250 | 15–20 years |
Modern pressure-treated lumber uses ACQ (Alkaline Copper Quaternary), not the old CCA that was banned in 2003. Current research shows ACQ-treated wood is safe for vegetable gardens, but if concerned, line the inside with landscape fabric or plastic sheeting.
| Item | Est. Cost | |
|---|---|---|
| 2×12 × 8 ft boards | $40–$80 | |
| 2×12 × 4 ft boards (or cut one 8 ft board) | $20–$40 | |
| 4×4 × 12" corner posts (optional, for rigidity) | $10–$15 | |
| 3" exterior wood screws | $8–$12 | |
| Cardboard or landscape fabric (bottom) | $0–$10 | |
| Lumber & hardware total | $78–$157 |
This is where most people mess up. Don't fill with garden soil or straight topsoil — they compact and drain poorly in a raised bed. Use one of these proven mixes:
| Mix Name | Components |
|---|---|
| Mel's Mix | 1/3 compost, 1/3 peat moss, 1/3 vermiculite |
| All-Purpose | 60% topsoil, 30% compost, 10% perlite or coarse sand |
| Rich Garden | 50% topsoil, 25% compost, 25% aged manure |
For a 4×8 bed at 12″ deep (32 cu ft needed)
All-Purpose mix: ~19 cu ft topsoil + ~10 cu ft compost + ~3 cu ft perlite
Approximate cost: $80–$150 depending on whether you buy bagged or bulk.
Buying in bulk (by the cubic yard) is dramatically cheaper if you need more than about 1 cubic yard. A cubic yard of garden soil mix costs $30–$60 delivered vs $150+ for the equivalent in bags.
| Component | Cost Range |
|---|---|
| Lumber & hardware (cedar) | $120–$200 |
| Lumber & hardware (fir) | $60–$100 |
| Soil mix (bagged) | $100–$150 |
| Soil mix (bulk, 1+ yards) | $30–$60 |
| Total (cedar + bagged soil) | $220–$350 |
| Total (fir + bulk soil) | $90–$160 |
12 inches is the minimum for most vegetables. 18 inches gives roots more room and is better for carrots, potatoes, and parsnips. If building on top of concrete or heavily compacted soil, go 24 inches deep.
Cardboard (plain, no glossy print) is the best bottom layer — it suppresses weeds and breaks down within a season. Don't use landscape fabric on the bottom; it impedes drainage long-term. Some gardeners add a 3–4 inch layer of sticks and logs (Hügelkultur method) to improve drainage and add slow-release nutrients.
Modern ACQ-treated lumber (post-2003) is considered safe for raised bed gardens by university extension programs. The old CCA treatment containing arsenic was banned. If still concerned, line the interior with thick plastic sheeting.
At 12 inches deep, you need about 32 cubic feet of soil. That's 32 one-cubic-foot bags, or 16 two-cubic-foot bags. It's usually cheaper to buy bulk soil delivered if available in your area.
Late winter to early spring (February–March) gives you time to build and fill the bed before planting season. The soil needs 2–4 weeks to settle before planting. Fall is also good — build in October, fill with soil, and it'll be ready for spring.
No. Raised beds drain naturally through the bottom, especially if placed on bare ground. That's one of their main advantages over in-ground gardens. If placed on concrete or a hard surface, ensure the bottom isn't sealed — use spacers to allow water to escape from the sides.