6 Best Cedar Shims For Leveling Potting Benches For Stability

A wobbly potting bench isn’t just a nuisance; it’s a recipe for spilled seed trays and back strain during long sessions of transplanting. When the ground is uneven, even the sturdiest cedar workbench will eventually twist, compromising the joints and making precision work impossible. Securing a level foundation with the right shims is the simplest way to protect the longevity of your gardening equipment.

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Nelson Wood Shims Contractor Pack: Best Overall

For the hobby farmer who values consistency, the Nelson Wood Shims Contractor Pack is the gold standard. These shims provide a uniform taper that takes the guesswork out of leveling multiple legs across varying ground surfaces. Because they are sourced from quality cedar, they naturally resist rot and insect damage—a critical requirement for any structure kept outdoors near soil and moisture.

The volume provided in this pack makes it an ideal choice for outfitting an entire shed or multiple greenhouse work areas. Since they are easy to score and snap, they fit perfectly under the uneven legs of repurposed furniture often pressed into service as potting stations.

Choose this product if the goal is a reliable, no-nonsense solution that works immediately. It is the most sensible choice for the general-purpose farmer who needs to level a bench today and forget about it until next season.

Swan Secure 8-Inch Cedar Shims: Most Durable

Durability becomes a priority when a potting bench sits directly on dirt or mulch rather than a concrete slab. The Swan Secure 8-Inch Cedar Shims are engineered with a thicker profile than standard alternatives, preventing them from crushing under the weight of heavy ceramic pots or wet soil bags. Their superior grain density ensures that they maintain structural integrity even after repeated seasonal cycles.

Because these shims are slightly longer than the average, they offer a wider contact point between the bench leg and the ground. This increased surface area distributes weight more effectively, which is essential for keeping a bench stable on soft garden paths.

If the bench holds significant weight—like large, water-saturated troughs or heavy machinery—do not settle for thinner, cheaper wood. These shims represent a necessary investment in the longevity of the workbench.

EZ-Shim Composite Shims: Best for Wet Areas

While wood is traditional, it does eventually succumb to the constant moisture of an active greenhouse environment. EZ-Shim Composite Shims offer a synthetic alternative that eliminates the risk of swelling or rotting, regardless of how often water splashes onto the feet of the bench. They are essentially immune to the damp conditions that often cause natural wood to degrade over time.

These composite units are designed to interlock, which creates a stable, tiered base that won’t slide or shift when the bench is bumped. This is particularly useful on slick greenhouse flooring where traditional cedar might lose traction.

For those operating in high-humidity climates or zones with frequent heavy rainfall, these composite shims are the superior choice. They function reliably in environments where wood would eventually require replacement.

The Shim Jim 42-Pack: Best Value for Money

Managing a hobby farm requires keeping overhead costs in check, and the Shim Jim 42-Pack serves this purpose perfectly. Providing a high volume at a lower price point, this pack is designed for the farmer who needs to level multiple surfaces at once without breaking the budget. They are thin, flexible, and exceptionally easy to manipulate for precise adjustments.

While they may not be the thickest option available, their versatility is unmatched for fine-tuning minor wobbles. Simply layering two or three of these shims can account for even the most erratic stone or dirt flooring, making them an excellent tool for quick fixes.

This product is highly recommended for those with several potting stations or equipment stands to manage. It delivers the essential utility required for basic bench stability without unnecessary expense.

Perfect Level Master Shims: For Heavy Benches

When the potting bench is constructed from heavy timber or holds significant inventory, the shims must support immense pressure without splintering. Perfect Level Master Shims provide the structural rigidity necessary to handle hundreds of pounds of soil, tools, and irrigation supplies. Their composition is calibrated to resist the “crush factor” that often destroys softer wood shims.

These shims are not for light-duty furniture; they are built for the heavy lifters of the agricultural workspace. Their specific density ensures that the bench remains locked in place, preventing the microscopic movements that eventually loosen joints and hardware.

If the bench acts as a workstation for heavy equipment or bulk supply storage, do not compromise with generic wood. Select these for the assurance that the leveling will remain permanent under heavy loads.

DIY-SHIM 12-Inch Shims: Best for Large Gaps

Sometimes, a workspace is so uneven that standard, shorter shims cannot bridge the distance between the floor and the bench leg. The DIY-SHIM 12-inch option provides the extra length required to create a stable ramp-like support for deep depressions. This length allows for a shallower incline, which is much safer and less prone to sliding out from under the load.

Having a few of these longer shims on hand is wise for anyone working on natural ground or uneven flagstone paths. They offer the reach necessary to bridge gaps that would otherwise require multiple smaller shims stacked precariously on top of one another.

Keep these on hand for the specific purpose of handling large ground inconsistencies. They turn a difficult leveling task into a straightforward process of finding the right height along a longer taper.

How to Properly Level a Potting Bench with Shims

Start by placing a carpenter’s level on the work surface in both directions to identify exactly which legs need support. Once the low corners are identified, slide the shim under the leg until the bubble centers, but avoid forcing the shim in so tightly that it lifts the bench too high. Always use the thinnest part of the shim to begin the contact, ensuring a gradual and firm transition.

Test the stability by applying downward pressure on different corners of the bench. If the bench still rocks, add a second shim from the opposite direction to create a flat, box-like support base. This “cross-stacking” technique prevents the bench from tipping if the floor shifts during the freeze-thaw cycles of the year.

Cedar vs. Plastic Shims: Which Is Right for You?

The decision between cedar and plastic usually comes down to the environment and the intended lifespan of the project. Cedar provides a natural aesthetic and excellent rot resistance, making it the preferred material for wood-frame potting benches in traditional garden settings. It has a slight bit of “give” that helps grip the floor surface, which is a major advantage on concrete or pavers.

Plastic or composite shims are far superior for high-moisture zones or where the shim will be buried partially in soil. They will never swell, rot, or attract insects, making them the “set it and forget it” choice for outdoor operations. However, they can be more slippery than wood, so ensure the surface has a textured finish to prevent the bench from shifting during use.

Securing Shims for Long-Term Bench Stability

A shim that is not secured is only a temporary solution; it will eventually work itself loose as the bench vibrates. Once the bench is perfectly level, mark the perimeter of the shims on the floor and the leg. If possible, drive a small construction screw through the side of the leg into the shim to anchor it firmly.

For shims placed on hard surfaces like concrete, a small bead of heavy-duty construction adhesive between the floor and the shim prevents sliding. This creates a permanent footing that will hold up even when the bench is dragged or re-positioned during seasonal cleaning. Stability is a function of friction, so ensure the shim-to-floor contact is as secure as the shim-to-leg connection.

Trimming and Finishing Shims for a Clean Look

Once the bench is level and stable, the excess length of the shim will likely protrude from the base of the leg. Using a sharp wood chisel or a fine-toothed pull saw, trim the excess material flush with the leg. This prevents the shims from becoming a tripping hazard and gives the workspace a professional, tidy appearance.

If using cedar, apply a small amount of outdoor-grade wood sealant to the freshly cut end to prevent moisture absorption. For composite shims, a quick sanding of the cut edge will smooth out any burrs left by the saw. Taking these final steps ensures that the leveling effort remains functional and aesthetically pleasing for seasons to come.

Properly leveled equipment is the mark of an efficient farm, ensuring that your time is spent on production rather than fixing shaky surfaces. Take the time to secure your potting bench correctly, and the foundation will serve you well through years of heavy harvests.