Potting Bench / Garden Workbench

A potting bench is one of the most useful small timber projects in a UK garden — and one of the easiest to get wrong by copying indoor bench logic outdoors.

The failure mode is almost always moisture, not joinery complexity. A flat, non-draining top holds compost slurry and rain. Legs buried in soil wick water into the frame. Timber may be “treated” but not for the contact conditions you actually built.

This guide walks through a simple, drained, replaceable bench using stock from a normal UK merchant, with fixings that survive damp cycles and dimensions that suit real potting work.

A potting bench succeeds when you treat it as outdoor furniture that gets dirty, not an indoor bench moved outside. Drain the top, keep legs out of soil, use exterior fixings, and build slats you are willing to replace later.

Works well on a level patio, greenhouse threshold or firm path where legs sit on paving or pads with airflow underneath; sheltered side returns that dry between sessions; kitchen gardens where you want height without going indoors.

Think twice on fully exposed coastal or hilltop sites, shaded north-facing niches where timber rarely dries, or soft lawn without feet or pavers (legs sink; moisture sits at the grass line).

Not for heavy workshop work (vise, planing, machinery) or climbing or sitting loads — light-duty garden station only.

Measure elbow height with shoes on before fixing leg length. Add a centre leg or mid rail on wide (1500–1800mm) variants. Wall-leaning and sink-ready versions need sound fixings and drainage — advanced, not the default. Light-duty only; not structural engineering advice. Verify use-class labels on merchant stock before publish.

Top overhang 20–40mm past the frame sheds water off leg tops. Lower shelf 150–200mm below top slats. Plan cuts from 2.4m stock; batch-cut slats with a spacer block.

Default footprint: 1200 × 600mm.

Work height: 850–950mm finished (from user elbow height).

Top: 120×25mm slats with 10–15mm gaps; optional 20–40mm front overhang.

Lower shelf: 150–200mm below top slats.

Standard (recommended) — slatted top, lower shelf, four legs, optional rear lip.

Compact (~1000 × 500mm) — small patios; same height logic.

Wide (1500–1800mm) — add centre support to limit rail sag.

Sink-ready — bowl cut-out; maintain drainage; consider a separate guide.

Wall-leaning — fix to solid structure only; not a default.

Mobile — castors compromise stability when pressing down while potting; not recommended as default.

Default: treated European redwood frame and slats, 1200 × 600mm footprint, slatted top with 10–15mm gaps, galvanised or stainless exterior screws. Frame: 75×75mm legs (or 90×90mm if stocked), 45×95mm rails, 120×25mm top slats. Optional low rear lip. Optional translucent exterior oil on visible faces after dry-in — not on trapped wet joints.

Larch: credible alternative where local stock is good; same drainage and fixings discipline.

Douglas fir: fine for frame if straight, dry-graded; keep slats narrow.

Western red cedar: excellent for slats if budget allows; softer, dents more easily.

Oak: usually unnecessary — heavy and costly for this role.

Do not use plywood or OSB on the upper surface; ply on the lower shelf only if kept off the ground and accepted as replaceable.

Exterior-grade stainless or hot-dip galvanised screws. Typical: 4.5–5.0 × 50mm for slats; 5.0–6.0 × 75–90mm for frame (adjust to timber thickness). Pre-drill slat ends.

Brush off compost when you finish; do not leave wet soil mats on the top. Expect top slats to be the wear item — plan to replace them in later years. Re-tighten screws after the first season. Refresh oil only if you chose an oil finish and water no longer beads.