What's inside
As an Amazon Associate I earn from qualifying purchases. This post may contain affiliate links at no extra cost to you.
Contents
Build Overview
A wooden potting tray gives you a contained work area for filling pots, mixing small batches of soil, and starting seedlings without scattering compost across the bench. This version adds a removable soil-sifting screen, so you can break up clumps or screen fine seed-starting mix when needed.
The tray is sized at roughly 24 inches long by 16 inches wide, with 3-inch sides. That is large enough for several nursery pots but still manageable on a workbench. Plan on two to four hours for construction, plus finish-drying time. The project is suitable for a beginner who can make reasonably straight cuts and drive screws without splitting the wood.
Materials and Tools
Use inexpensive, straight 1×4 boards for the sides and 1×2 stock for the bottom supports and screen frame. Cedar lasts longer around damp soil, but ordinary pine is cheaper and works well if you keep the tray under cover and let it dry after use.
- Two 1×4 boards, 24 inches long, for the long sides
- Two 1×4 boards, 16 inches long, for the end sides
- One 1/2-inch exterior plywood bottom, 23 1/4 by 15 1/4 inches
- Four 1×2 strips, 23 1/4 inches long, for the removable screen frame
- 1/4-inch galvanized hardware cloth, approximately 22 by 14 inches
- 1 1/4-inch exterior screws, 1-inch screws, wood glue, and 120-grit sandpaper
- Exterior paint, outdoor polyurethane, or deck sealer
You will also need a tape measure, square, pencil, drill/driver, 1/8-inch drill bit, countersink bit, clamps, and a stapler. A 1/4-inch galvanized hardware cloth is a better choice than chicken wire: its square openings stay rigid and do not deform as easily under a pile of soil.
| Screen opening | Best use | Trade-off |
|---|---|---|
| 1/4 inch | General potting mix, compost, and clump removal | Does not produce a very fine seed-starting mix |
| 1/8 inch | Seeds and fine-textured propagation mix | Clogs faster and takes longer to sift |
| 1/2 inch | Removing sticks and large debris | Lets smaller clumps pass through |
Cut and Prepare the Parts
Cut the long sides to 24 inches and the end sides to 16 inches. Before cutting, check the board for a bow. Put the crown, or outward curve, toward the outside of the tray. A slightly imperfect cut is acceptable, but the ends should be square enough that the corners close without a visible gap.
Cut the plywood bottom to 23 1/4 by 15 1/4 inches. These dimensions leave the bottom inside the side walls rather than extending past them. Dry-fit the four walls around the plywood. If your lumber is actually wider or narrower than nominal 1×4 stock, measure the opening and adjust the bottom before fastening it.
Sand the cut edges and knock off sharp corners. Do not aggressively round the inside edges; square inside corners help keep soil from collecting in deep gaps. If you are using pine, inspect for knots near the screw locations.
Assemble the Tray
Place the long sides parallel on a flat surface, then fit the end pieces between them. Apply a thin bead of exterior-rated wood glue to each joint. Clamp or hold the corners flush, drill pilot holes, and drive two 1 1/4-inch screws through each end side into the long side.
Check the assembly for square by measuring both diagonals. If the measurements differ by more than about 1/8 inch, push the longer diagonal inward before tightening the screws. A square tray makes the removable screen easier to install and prevents the bottom from rocking.
Turn the tray upside down and place the plywood bottom on the opening. Center it so the edges contact all four walls. Drill pilot holes every 6 to 8 inches and fasten with 1-inch screws. Keep the screws slightly below the surface so they do not catch a pot or scrape your workbench.
The bottom carries wet soil, which can weigh considerably more than dry mix. If you expect to fill the tray completely, add a 1×2 cleat beneath each long edge of the plywood. Screw the cleats to the side walls, not just into the plywood. This support is inexpensive insurance against a sagging bottom.
Make the Removable Sifting Screen
Build a second rectangle from the four 1×2 strips. Make the long strips 23 1/4 inches and the short strips 14 inches, so the short pieces fit between the long ones. Glue and screw the corners with 1-inch screws. Predrill every hole; 1×2 stock splits easily near its ends.
Lay the hardware cloth over the frame and cut it with tin snips, leaving about 1 inch of extra material on every side. Wear gloves because cut wire is sharp. Fold the edges over and staple the mesh to the underside of the frame every 2 to 3 inches. Pull it tight as you work, but do not stretch it so hard that the frame twists.
Set the screen inside the tray. It should drop in freely and lift out without catching. If it binds, sand the frame edges or trim a small amount from the mesh. A snug fit is useful, but a screen that needs prying will eventually damage the tray.
For a second screen, build another frame with a different mesh size. This costs less than building an entirely separate tray and lets you switch between rough compost screening and fine seed-starting work.
Finish and Use the Tray
Seal all surfaces, especially the plywood edges and end grain. An exterior water-based finish dries faster and has less odor; oil-based exterior finishes generally penetrate more deeply but require longer drying time. If you prefer paint, use an exterior enamel and allow it to cure fully before adding soil.
Do not use an unlined tray as a permanent container for wet soil. The bottom will eventually swell, screws may loosen, and mold can develop in trapped soil. A waterproof exterior wood sealer is worthwhile, but it will not replace drying and basic maintenance.
To sift, place a bucket or empty pot beneath the screen, add a few handfuls of soil, and shake the tray side to side. Do not overload it; 2 to 3 inches of material is easier to process than a full heap. Break stubborn clumps by hand rather than forcing them through, which can bow the mesh.
After spring and summer use, brush out the tray and store it on edge in a dry shed or garage. Inspect the mesh before the next season. If a staple has pulled out or a wire end is exposed, replace the staple or bend the wire flat before it scratches your hands or tears a seed packet.
Where to Spend and Where to Save
Save money on the tray itself by using sound pine or reclaimed boards, provided they are not pressure-treated, painted with unknown coatings, or contaminated with oil. Spend a little more on straight lumber and galvanized mesh. A cheap screen that sags will sift poorly and is harder to repair than a basic rigid one.
If you do not own tin snips, straight-cut tin snips are sufficient for this project; an expensive aviation set is unnecessary. Likewise, a manual staple gun is fine for one tray. A box of exterior wood screws is a better upgrade than decorative hardware because damp soil quickly exposes weak fasteners.