Hardwood in the garden: how to keep its natural strength and beauty
Tips & maintenance · Maintenance
MaintenanceKeeping hardwood in top condition
Hardwood asks for little, but not nothing. One treatment a year in spring is the difference between furniture that lives and furniture that merely stands there.
- Oil once a year
- No pressure washer
- Turning grey is not damage
What hardwood really needs
Hardwood does not rot easily and does not need protecting to survive. What you do, you do for its looks.
Tropical hardwood such as teak and iroko naturally contains oils and substances that deter fungi and insects. A hardwood garden bench that you leave alone for ten years will still be standing in ten years — only silver-grey instead of warm brown.
So maintenance here is about colour and the surface, not about lifespan. Dirt and green algae hold moisture and make the wood rough; a yearly clean solves that. An oil treatment afterwards keeps the warm tone and seals the surface.
The only real mistake you can make is a pressure washer at full power. It blasts away the soft fibres between the growth rings, so the surface becomes rough and actually holds dirt faster. What you clean in ten minutes then costs you years of smooth surface.
If you let the wood turn grey and in three years still want the warm colour back, you can largely bring it back by sanding and oiling. So doing nothing does not commit you to anything.
- Oiling
- once a year, in spring
- Right in the sun and rain
- twice a year is fine
- Cleaning
- lukewarm water, soft brush, mild or green soap
- Never
- pressure washer at full power
- Drying after cleaning
- 24 hours, preferably 48
- Sanding
- 120 to 180 grit, only where needed
- Winter
- can stay outdoors; a breathable cover extends its life
To be fair: oil is not a one-off decision but a subscription. Once you start, you have to come back every year, because a half-worn oil film looks blotchy — worse than untreated wood. If you do not fancy that rhythm, you are better off simply letting the furniture turn grey; that is a perfectly valid choice and it saves you an afternoon every spring.
In pictures · The big yearly treatment
Schematic drawing.
The big yearly treatment
- CleaningFirst brush away loose dirt, then wash the furniture with lukewarm water and a mild or green soap. Work along the grain. No pressure washer at full power — it damages the wood fibres.
- Let it dryAt least 24 hours, preferably 48 hours of dry weather. Oil on damp wood does not soak in and stays sticky on the surface.
- Sand lightly120 to 180 grit, only where the surface is rough or stained. Then wipe off the dust with a dry cloth.
- OilingApply thinly and evenly with a brush or cloth, along the grain. Wipe off excess oil after a quarter of an hour — whatever is left becomes sticky.
A bundle of rags soaked in wood oil can spontaneously catch fire while drying. Lay used rags out flat on a non-flammable surface or soak them in water before you throw them away.
Let it turn grey or not?
Do nothing
Under the influence of sun and rain, untreated hardwood weathers to a silver-grey patina.
- Purely cosmetic — no damage
- No yearly chore
- Uneven in colour for the first few years
- Still clean it against green algae
- Always reversible with sanding and oiling
Oil every year
One treatment a year keeps the warm, original tone.
- Deeper colour and visible figure
- Surface stays sealed and smooth
- Come back every year, or it becomes blotchy
- Choose an oil in the colour of your wood
- Two treatments for furniture right in the sun and rain
Green algae, stains and winter
Green algae
Remove algae with lukewarm water, a soft brush and green soap. Stubborn? Let the soapy water work for ten minutes and then brush along the grain. Afterwards, put the furniture in a more open spot: algae thrive on moisture and shade.
Grease stains
Soak up as quickly as possible with kitchen paper, do not rub. Then degrease with soapy water. An old grease stain in untreated hardwood can be sanded out.
Black dots
Often mould spots on damp wood, sometimes a reaction with metal. Sand lightly and make sure there is more air circulation around the furniture.
In winter
Hardwood can withstand frost and can stay outdoors. Putting it away under cover or using a breathable cover extends its life: fewer moisture cycles mean less movement in the wood.
Never wrap it airtight
A plastic sheet traps moisture and causes condensation. That is more harmful than ordinary rain.
Cushions separately
Even if the fabric is water-resistant: cushions left outside for months collect dirt and algae. In a cushion box they last years longer.
Frequently asked questions about hardwood maintenance
How often should I oil hardwood garden furniture?
Once a year is enough for most hardwood species, preferably in spring after cleaning. If the furniture stands right in the sun and rain, twice a year is fine.
How do I remove green algae?
With lukewarm water, a soft brush and green soap. For stubborn algae, let soapy water work for ten minutes and brush along the grain.
Can I use a pressure washer?
Preferably not, and certainly not at full power. It blasts away the soft fibres between the growth rings, so the surface becomes rough and holds dirt faster.
Can hardwood stay outdoors in winter?
Yes, hardwood can withstand frost. A breathable cover or putting it away under cover does extend its life. Never wrap it airtight: condensation is more harmful than rain.
Is turning grey harmful?
No, it is purely cosmetic. And it is reversible: by sanding and oiling you largely bring back the warm colour.
Which oil should I choose?
A wood oil in the colour of your wood. An oil that is too dark closes up the figure; one that is too light lets the grey show through.
Everything for the yearly treatment
Wood oil in the right colour, and the furniture worth such a treatment.
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