Every gardener who builds a cedar raised bed or outdoor furniture eventually faces the same question: should I put a finish on this wood, or leave it bare? The answer is not as obvious as it sounds, and the finish aisle at the hardware store makes it worse — shelves of oils, stains, sealers, and varnishes, each claiming to be the best choice for outdoor wood. Most of them are wrong for garden use.
I have tried every finish discussed in this article on my own garden projects over the past twelve years. Some performed beautifully. Some were a waste of time. And in several cases, leaving the wood completely bare turned out to be the best choice. The right approach depends on the wood species, the project, and how much maintenance you are willing to do. Our materials and buying guides help you choose the right products for every garden project, and this finish comparison is one of the most frequently asked questions we receive.
When to Finish and When to Let Weather
Not all outdoor garden wood needs a finish. In fact, applying the wrong finish to certain species can cause more harm than good by trapping moisture, encouraging mildew, or peeling off in ugly sheets.
Leave Bare: Cedar and Redwood Raised Beds
Western red cedar and redwood contain natural oils (thujaplicins in cedar, tannins in redwood) that resist rot, fungal growth, and insect damage without any added treatment. A cedar raised bed left completely bare will weather to a silver-grey patina over 12-18 months and then remain structurally sound for 15-20 years depending on climate and soil contact.
Applying a finish to a raised bed that holds soil is problematic for two reasons. First, the interior face of the bed is in constant contact with moist soil, and no topical finish survives that environment for long — it peels, flakes, and looks worse than bare wood within a season. Second, any finish on the interior face is in direct contact with soil where you grow food. While most exterior wood finishes are non-toxic once cured, "non-toxic" is a relative term, and keeping unnecessary chemicals away from your vegetable soil is sensible.
My recommendation for cedar and redwood raised beds: leave them completely bare. Enjoy the warm honey colour of fresh wood for the first year, accept the silver weathering as a design feature, and let the natural durability of the species do its job.
Finish: Outdoor Furniture and Non-Soil-Contact Projects
Garden benches, tables, arbors, planters (exterior only), trellises, and decorative structures benefit from a finish because preserving the original wood colour is often desirable and the wood is not in constant contact with soil or food. A quality oil finish penetrates the wood fibres, slows moisture absorption, reduces UV-driven greying, and keeps the wood looking warm and maintained rather than weathered and neglected.
Oil Finishes Compared
Pure Tung Oil
Tung oil is pressed from the nut of the tung tree. It has been used as a wood finish for centuries, and it is one of the best natural options for outdoor garden projects. Pure tung oil penetrates deeply into wood fibres, polymerizes (hardens) when exposed to oxygen, and creates a water-resistant finish from within the wood rather than sitting on the surface as a film.
Application: thin the first coat 50/50 with citrus solvent or mineral spirits to help it penetrate. Apply with a rag, let it soak for 20-30 minutes, wipe off the excess. Let it cure for 24-48 hours. Apply a second coat at full strength, same process. Two coats is sufficient for outdoor garden projects; a third coat adds marginal improvement. Full cure takes 7-14 days depending on temperature and humidity.
Tung oil does not peel or flake because it is in the wood, not on it. As it weathers, the finish fades gradually rather than failing catastrophically. Reapply once a year for outdoor projects — a single maintenance coat takes 20 minutes and keeps the finish looking fresh. Our guide on weatherproofing without chemicals covers tung oil application in more detail for furniture specifically.
Boiled Linseed Oil
Linseed oil is pressed from flax seeds. The "boiled" version is not actually boiled — it contains metallic drying agents that speed the cure time from weeks (raw linseed oil) to 24-48 hours. It is inexpensive, widely available, and has been a traditional wood preservative for hundreds of years.
Application is similar to tung oil: thin the first coat, apply with a rag, wipe off excess, let it cure, apply a second coat. Boiled linseed oil is less water-resistant than tung oil and less UV-resistant, so it requires reapplication twice a year on outdoor projects — once in spring and once in late summer. It also tends to darken wood more than tung oil and can develop a slightly tacky surface in humid conditions.
The main advantage of linseed oil is price — a quart costs about half what tung oil costs. For utilitarian projects like trellis frames or tool handles where appearance is secondary to protection, linseed oil is a perfectly reasonable choice. For furniture and visible projects where you want the best appearance, tung oil is worth the premium.
Danish Oil
Danish oil is a blend of oil (usually tung or linseed), varnish, and thinner. The oil penetrates, the varnish hardens, and the result is a finish that is tougher than pure oil but easier to apply than straight varnish. It produces a subtle sheen rather than a glossy film.
Application: brush or wipe on, let soak 15-20 minutes, wipe off excess, let cure 24 hours, apply a second coat. Two coats provides good protection. Danish oil gives the best single-product balance of penetration, protection, and appearance for outdoor furniture. The varnish component adds UV resistance that pure oils lack.
The downside: the varnish component eventually breaks down under UV exposure and weathering, and when it does, the surface can look blotchy as some areas fail before others. Reapplication annually addresses this, but if you fall behind on maintenance, you may need to lightly sand the surface before recoating — something you never need to do with pure oil finishes.
Cedar Oil
Cedar oil (not the essential oil, but wood-treatment-grade cedar oil) is less common than tung or linseed but worth considering if you are finishing cedar projects and want to maintain the species' natural scent and warm colour. It is extracted from cedar wood and bark and serves as both a preservative and a finish.
Cedar oil penetrates well but does not polymerize the way tung oil does — it remains a liquid within the wood fibres and gradually evaporates over time. This means it provides less long-term protection than tung oil and requires more frequent reapplication (every 6-8 months for outdoor projects). Its strengths are colour enhancement (it deepens cedar's natural warmth without changing the hue), insect resistance (the cedar compounds repel termites, ants, and moths), and the fact that it is arguably the most food-safe option for projects near garden soil.
Cedar oil makes the most sense for cedar furniture and decorative projects where maintaining that specific cedar character matters. For maximum durability, tung oil is a better choice.
Application Technique for Raised Beds and Furniture
Regardless of which oil you choose, proper application technique makes the difference between a finish that lasts and one that disappoints.
Surface preparation: Sand the wood to 150-180 grit. This is not about making it perfectly smooth — it is about opening the wood pores so the oil can penetrate. Do not sand finer than 180 grit for oil finishes; too-smooth wood actually resists oil penetration. Remove all sanding dust with a tack cloth or damp rag.
Application: Use a lint-free cotton rag, not a brush. Fold the rag into a pad, dip it in oil, and wipe with the grain in long, even strokes. Apply generously — you want the wood to absorb as much as it will take. Flood it on and let it soak.
Wait and wipe: Let the oil sit on the surface for 15-30 minutes. You will see some areas absorb faster than others — end grain drinks oil, face grain is slower. After soaking, wipe off all excess with a clean rag. This step is critical. Oil left sitting on the surface will not cure properly and becomes a sticky, dust-attracting mess. Wipe until the surface feels dry to the touch.
Cure time: Let the first coat cure for 24-48 hours in a well-ventilated area before applying the second coat. Do not rush this. If the first coat is not fully cured, the second coat cannot penetrate properly.
Safety note: Oil-soaked rags can spontaneously combust. This is not an exaggeration — linseed oil and tung oil generate heat as they polymerize, and a wadded-up rag can reach ignition temperature. Lay used rags flat on a concrete surface to dry, or submerge them in a bucket of water. Never throw oil-soaked rags in a bin or pile them together.
Reapplication Schedule
Every oil finish on outdoor wood is temporary. UV light, rain, and temperature cycling gradually break down and wash out the oil. Here is a realistic maintenance schedule based on my experience in a zone 6 climate with four distinct seasons:
- Pure tung oil: Reapply once per year, in early spring after the last frost. One coat is sufficient for maintenance — you only need the multi-coat process for the initial application.
- Boiled linseed oil: Reapply twice per year — early spring and late summer. Linseed weathers out faster than tung and benefits from the second application.
- Danish oil: Reapply once per year. Lightly sand any areas where the varnish component has visibly deteriorated before recoating.
- Cedar oil: Reapply every 6-8 months. It evaporates rather than polymerizing, so it simply does not last as long as the others.
Wood Worth Finishing
Browse our cedar raised beds and garden furniture — crafted from western red cedar that looks beautiful bare or finished with the oil of your choice.
Frequently Asked Questions
Is tung oil food safe for raised beds?
Pure tung oil is considered food safe once fully cured (7-14 days). It has no volatile organic compounds once polymerized and is approved for food-contact surfaces like cutting boards and wooden bowls. That said, I still recommend leaving the interior of food-growing raised beds unfinished — the soil contact degrades any finish quickly, making the effort pointless. If you want to finish the exterior for appearance, pure tung oil is the safest choice.
Can I use polyurethane or marine varnish on outdoor garden wood?
You can, but I do not recommend it for most garden applications. Film-forming finishes like polyurethane sit on the surface of the wood rather than penetrating it. When they eventually fail (and they will, on outdoor wood), they crack, peel, and flake — requiring complete removal by sanding before you can refinish. Oil finishes fade gracefully and can be recoated directly without stripping. The only garden application where I would consider polyurethane is a tabletop that needs maximum water resistance, and even then, marine-grade spar varnish is a better choice than standard polyurethane because it flexes with wood movement.
What about pressure-treated wood — does it need a finish?
Pressure-treated wood is infused with preservatives that prevent rot and insect damage, so it does not need a finish for protection the way untreated pine would. However, pressure-treated wood weathers to an unattractive grey-green colour without a finish. If appearance matters, apply a pigmented stain (semi-transparent or solid) rather than a clear oil — the pigment provides UV protection that clear finishes cannot match on treated lumber. Wait 3-6 months after installation for the wood to dry sufficiently before applying any finish to pressure-treated material.