Raised garden bed.

Use naturally durable or appropriately treated exterior timber that is suitable near edible crops according to its supplier. Actual board size for this plan is 45 × 145 mm.

• 48 exterior structural screws, 6 × 100 mm
• Geotextile for the base if weeds are persistent; never use an impermeable plastic floor
• Cardboard without tape or glossy coating, optional
• Approximately 530 litres of settled raised-bed mix, allowing a 50 mm watering rim

The 900 mm width assumes access from both long sides. If the bed will sit against a wall, reduce it to roughly 600 mm so the back remains reachable.

1. Choose the site. Check sunlight, water access and underground services. Remove perennial weeds. Mark an 1,800 × 900 mm rectangle and level the perimeter; do not build across drainage paths.
2. Cut and seal. Cut all boards square, label the three courses and treat freshly cut end grain as required by the timber supplier.
3. Build the first course. Put the long boards outside the 810 mm end boards. Clamp them around the four corner posts, with post tops flush. Pre-drill and use two 100 mm structural screws per board end.
4. Square the frame. Measure both diagonals; they should match. Level every side and support low points with compacted mineral material—not loose soil.
5. Add the upper courses. Stack boards tightly, alternating screw heights so fasteners do not collide. Fix each board end to its corner post.
6. Control bowing. Fix one stake at the midpoint of each long side. Drive or anchor it at least 150 mm into suitable ground, leaving its top flush with the bed. Do not drive where services may be present.
7. Prepare the floor. Loosen compacted soil. Lay overlapping plain cardboard for weed suppression if needed, then wet it. Use permeable geotextile only where root or pest conditions justify it.
8. Fill in layers. Add a suitable raised-bed blend in 150 mm layers, watering lightly between lifts. Stop 40–50 mm below the rim for mulch and watering space.

The internal footprint is approximately 1,710 × 810 mm. Filled to 385 mm, leaving a 50 mm watering and mulch rim, its usable volume is about 533 litres. Order roughly 530–550 litres depending on settlement, but do not pack soil hard.

• Do not add a gravel layer; an abrupt texture change can hold water above it.
• Keep the base open to the ground unless you need a suitable pest mesh.
• Use compost as part of a balanced mix, not as the only material.
• Mulch after planting, keeping mulch clear of young stems.

Check for outward bowing, loose fasteners, decay at soil level and sharp edges. Top up settled soil with appropriate compost and growing medium. Avoid standing on the boards, and replace a softened member before the soil pressure opens the joint.