Key takeaways
- Timber edging is cheap, easy to cut, and forgiving if you get a curve wrong. The catch is that wood rots, and the species you choose decides whether you’re redoing this job in three years or fifteen. If you want…
Timber edging is cheap, easy to cut, and forgiving if you get a curve wrong. The catch is that wood rots, and the species you choose decides whether you’re redoing this job in three years or fifteen. If you want edging that lasts, you need to think about ground contact ratings, not just what looks good at the garden center.
What actually kills timber edging
Edging boards sit half-buried, which is the worst possible environment for wood. One face is exposed to sun and air, the other is jammed against damp soil. That moisture gradient is what causes cupping, splitting, and rot at the soil line first. Fence posts fail at the same spot for the same reason. If a timber isn’t rated for ground contact, expect visible decay within 2-4 years, especially in clay soil that holds water against the board.
Ants and termites are the other failure mode, particularly with untreated softwood in warmer climates. You won’t see it coming until a board that looked fine snaps when you kneel on it.
Best species and treated options
Pressure-treated pine is the default answer for a reason: it’s inexpensive, straight, and rated for ground contact when you buy the right grade (look for “ground contact” on the tag, not just “treated”). It will outlast untreated hardwood in most climates. The trade-off is the chemical treatment leaches slightly for the first season, so keep it away from vegetable beds if that bothers you, and wear gloves when cutting it since the dust is nastier than plain wood.
Cedar and redwood are the natural-rot-resistance options. Cedar heartwood holds up for 10-15 years in ground contact without any chemicals, and it looks better as it weathers to silver-gray. The downside is cost, often 2-3x pressure-treated pine, and availability varies a lot by region. If you’re on the West Coast, redwood edging is often cheaper and just as durable as cedar. If you’re not near either supply chain, you’re paying freight for both.
Black locust and white oak are the hardwood options serious DIYers overlook. Black locust in particular rivals treated lumber for ground-contact life (20+ years isn’t unusual) and takes a sharp edge well if you’re hand-cutting curves. It’s hard to find at a regular lumberyard, so you’re often sourcing from a specialty mill, which adds cost and lead time.
Untreated pine, fir, or construction-grade softwood is the one to skip for permanent edging. It’s fine for a season of temporary garden bed borders or a project you plan to replace anyway, but in ground contact it’s typically rotted through within 18-24 months. If you’ve already got offcuts lying around, use them for the job, just don’t buy new untreated softwood expecting it to last.
Timber options compared
| Timber | Typical ground-contact life | Relative cost | Best for |
|---|---|---|---|
| Pressure-treated pine (ground contact rated) | 8-15 years | Low | Most yards, budget projects, straight runs |
| Cedar heartwood | 10-15 years | High | Visible edging where appearance matters |
| Redwood | 10-15 years | Medium-high (West Coast), high elsewhere | Same as cedar, cheaper if local |
| Black locust / white oak | 15-25 years | Medium-high, hard to source | Long-term installs, hand-shaped curves |
| Untreated softwood | 1-2 years | Very low | Temporary beds only |
Installation details that matter more than species
Even good timber fails early if it’s installed badly. Bury at least a third of the board’s height, 2-3 inches minimum for a 4-6 inch board, so it has something to resist frost heave and mower contact. Backfill with the same soil you dug out rather than loose gravel against the wood face; gravel drains well but also lets more air and moisture cycle against the timber, which speeds rot at that contact line.
Stake it. Edging that isn’t pinned down shifts within a season, especially after a hard freeze-thaw cycle. Galvanized landscape stakes or rebar driven at 3-4 foot intervals hold a straight run fine; for curves, shorten that interval to 18-24 inches so the board doesn’t bow outward over time. A cordless drill driver makes pre-drilling stake holes and driving screws through the board into the stake much faster than hand tools, and it reduces splitting compared to hammering nails through the edge.
For cutting curves or notching corners, a basic hand saw is enough for most residential jobs; you don’t need a circular saw for edging unless you’re doing long straight runs where speed matters. If you’re setting a lot of linear footage and want it level, a basic string line and a rubber mallet to tap boards into position without marring the wood will save you more time than any power tool will.
When to skip timber entirely
If you’re edging a bed that gets regularly scraped by a mower or string trimmer, timber takes a beating faster than steel or composite edging will, regardless of species. The repeated nicks from a trimmer line eventually chew through even cedar. In high-traffic edges like that, it’s worth pricing out steel landscape edging instead; timber makes more sense for beds where the mower stays a few inches clear and the main stress is just soil and moisture.
And if your soil stays consistently wet, like a low spot that puddles after rain, no timber species will give you more than a few good years. That’s a drainage problem first, and edging material second.
