Top 10 Hardwood Trees for Durable, Sturdy Garden Furniture
The Wood Guide · Trees
TreesTen broadleaf trees and their wood
Botanically, the wood of every broadleaf tree is hardwood. In the garden, that means nothing at all — and every year that difference costs people a set of garden furniture.
- Hardwood ≠ durable
- Only two can go outdoors
- Heartwood counts, sapwood doesn’t
Hardwood is a botanical term
Hardwood means: from a broadleaf tree. It says nothing about how hard the wood is, and certainly nothing about how long it lasts outdoors.
Balsa is botanically a hardwood, yet you can press your thumb into it. Poplar and willow are hardwoods and rot outdoors within a few years. Pine, meanwhile, is a softwood, and properly pressure-treated it lasts for decades. So the softwood–hardwood split tells you about the tree family, not about what the wood is good for.
What you need outdoors is durability class: the natural resistance of the heartwood to fungi and insects, from class 1 to 5. Of the ten trees below, exactly two reach class 1 or 2 — the rest belong indoors, or need treating.
And for every species, only the heartwood counts. The paler sapwood on the outside of the trunk is not durable in almost any tree, however well the species scores otherwise.
Of this list, only oak heartwood and robinia can go outdoors untreated. All the others are beautiful indoor woods, or outdoor wood only when pressure-treated.
- Hardwood means
- from a broadleaf tree — nothing more
- What does count outdoors
- durability class 1 to 5
- Robinia
- class 1–2 — Europe’s standout
- Oak heartwood
- class 2
- Walnut
- class 3 — indoor wood
- Birch, poplar, willow
- class 5 — not durable
- Sapwood
- not durable in any species
To be fair: the list below reads like ten options, but for garden furniture there are really two. That is not a shortcoming of our trees but of our climate: few species that grow in Western Europe can naturally withstand years of rain. That is why pressure treatment exists, and why tropical hardwood comes from far away.
Hardwood means: from a broadleaf tree
It says nothing about how hard the wood is, and certainly nothing about how long it lasts outdoors. Balsa is botanically a hardwood and you can press your thumb into it. Pine is a softwood, and properly impregnated it lasts for decades.
Click a chapter or use the arrows · the rain test shows the order by durability class, not years.
The two that last outdoors
Robinia — Robinia pseudoacacia
Also known as black locust or false acacia. Durability class 1–2, which makes it the only European species that can match tropical hardwood. Golden yellow that deepens with age, and naturally resistant to rot and insects. The tree grows twelve to thirty metres tall. Its only drawback: it often grows crooked, so long straight lengths are scarce and expensive.
Oak — Quercus
Heartwood class 2: durable, strong, and with a figure that lasts for generations. A pedunculate oak can reach thirty metres and live for centuries. Two points to watch: the tannic acid reacts with iron to leave blue-black stains, so use stainless steel fittings, and the pale sapwood should be cut away for outdoor use.
The other eight: beautiful, but for indoors
| Tree | Wood | Class | What it is good for |
|---|---|---|---|
| Black walnut (Juglans nigra) | dark, luxurious, deepens with age | 3 | furniture, veneer, indoor tabletops |
| Maple (Acer) | pale, fine-grained, shock-resistant | 5 | indoor furniture, floors, bent parts |
| Ash (Fraxinus) | flexible and shock-resistant | 5 | tool handles, chairs, sports equipment |
| Birch (Betula) | light in colour and weight | 5 | plywood, light furniture, interior work |
| Poplar (Populus) | very light, fast-growing | 5 | packaging, board materials, interior work |
| White willow (Salix alba) | flexible, light | 5 | wickerwork, baskets, decorative pieces |
| Elm (Ulmus) | strong, striking grain | 4 | indoor furniture; susceptible to Dutch elm disease |
| Alder (Alnus) | soft, orange-red after sawing | 5 above water, exceptional below it | interior work — but piles under water last for centuries |
Above ground, alder is not durable, but fully submerged it lasts for centuries — without oxygen, rot fungi cannot get at it. Large parts of Venice and Amsterdam stand on alder and pine piles. As soon as the water table drops and the pile heads dry out, decay sets in after all.
What does this mean for your garden furniture?
Robinia or oak
If you want European hardwood that can go outdoors untreated, these are your two options. Expect a price that reflects this, and limited availability in long straight lengths.
Pressure-treated softwood
The affordable route, and the reason most garden furniture is made of spruce. Pressure-treated, it lasts for years — joints included.
Tropical hardwood
Teak and iroko reach class 1–2 without treatment. They are heavier and more expensive, though, and their origin is an extra question to ask.
Modified wood
Thermally or chemically modified softwood reaches the durability of tropical hardwood, with an origin closer to home.
Indoor wood is not inferior
Walnut, maple and ash are beautiful furniture woods. They just don’t belong in the rain, and that is not a judgement on their quality.
Ask for heartwood
With every species. Sapwood is never durable, not even in robinia or oak.
Frequently asked questions about broadleaf trees and their wood
Does hardwood mean the wood is hard?
No. Hardwood means it comes from a broadleaf tree. Balsa is a hardwood and remarkably soft; pine is a softwood and, pressure-treated, lasts for decades outdoors.
Which European tree gives the most durable wood?
Robinia, also known as black locust or false acacia. With durability class 1–2, it is the only European species that can match tropical hardwood.
Can oak go outdoors untreated?
The heartwood can — it is class 2. The paler sapwood cannot. Also use stainless steel fittings: tannic acid reacts with iron to leave blue-black stains.
Can I use poplar or willow for garden furniture?
Better not. Both are durability class 5 and rot away outdoors within a few years, even though they are botanically hardwoods.
Why is so much garden furniture made of tropical wood?
Because few species that grow in our climate can naturally withstand years of rain. Robinia and oak are the exceptions; otherwise, pressure treatment or import is the way to go.
Is it true that alder lasts for centuries under water?
Yes. Without oxygen, rot fungi cannot get at it. Parts of Venice and Amsterdam stand on alder and pine piles. As soon as the pile heads dry out, decay sets in after all.
More in The Wood Guide
Every tree and every wood species has its own page, with the figures.
Have a question about your project? Just ask — we're happy to help.
Photos via Wikimedia Commons: Robinia pseudoacacia — Gerda Arendt, CC BY-SA 4.0 · Quercus robur — AnRo0002, CC0 · Juglans nigra — R. A. Nonenmacher, CC BY-SA 4.0 · Acer pseudoplatanus — Gordon Leggett, CC BY-SA 4.0 · Betula pendula — Юрий Д.К., CC BY 4.0 · Populus × canadensis — AnRo0002, CC0 · Salix alba — AnRo0002, CC0 · Ulmus glabra — AnRo0002, CC0 · Alnus glutinosa — Willow, CC BY 2.5 · Fraxinus excelsior — Willow, CC BY 2.5