Summer heatwaves in the Czech Republic have been breaking records regularly in recent years, and as temperatures rise, so does the question of how to protect wood from the sun. A wooden planter on a south-facing balcony, a decoration on the terrace or a raised bed in full sun all have a tough time in July and August – strong UV radiation and the alternation of heat and drought dry the wood out, turn it grey and make it crack. The good news is that with just a few minutes of care during the season, outdoor wood can stay beautiful for years.
Before you start: get some fine sandpaper (grit around 180–240), a clean cloth or sponge, a bucket of lukewarm water and, above all, a good-quality exterior wood oil – ideally one that contains a UV filter or pigment. A brush or flat brush and some old newspapers to put underneath will also come in handy. Work in dry weather and out of the direct midday sun, so the oil soaks in evenly and does not dry too quickly. You can manage most of the steps in one calm afternoon.
How to protect wood from the sun, step by step
1. Find the right spot for the wood
The best protection is the kind the wood does not have to “endure” at all. In the Czech Republic, South Moravia and the Elbe lowlands get the most hours of sunshine, but a south-facing terrace in Prague or Brno can heat wood up in summer just as much. If the layout allows, place wooden decorations and accessories out of the direct midday sun – in partial shade, under a pergola, an awning or a roof overhang.
Planters with geraniums or herbs can happily stay on the railing – the plants themselves give the wood natural shade and help protect it. Smaller decorations, candle holders and accessories are better placed against the wall of the house or under a shelter, where the sun only reaches them in the morning or early evening.
2. Treat the surface with exterior oil before the season
The foundation of sun protection is the right surface finish. Apply a thin, even coat of exterior oil or wood stain to clean, dry and degreased wood. The oil penetrates the structure, replenishes natural moisture and creates a flexible protective layer that does not seal the wood in like varnish, but lets it “breathe”. Choose a product designed for outdoor use – ideally with a UV filter or a light pigment that reflects some of the radiation.
Pigmented oils have one big advantage over clear ones: the colour particles act as a tiny sunshade and slow down greying. For a natural look, a shade just one tone darker than the wood itself is enough.
Tip: Apply the oil in two thin coats rather than one thick one. Let the wood dry for a few hours between coats. Always wipe off any excess oil that has not soaked in after a few minutes – otherwise a sticky film will remain on the surface, attracting dust and pollen.
3. Oil regularly during the summer too
A single spring treatment is usually not enough for the whole season, especially for items in full sun. Repeat the oiling once or twice over the summer. You do not need to wait for a particular date – the wood will tell you when it needs care. As soon as the surface turns matt, stops repelling water (a drop no longer beads up but spreads and soaks in) or starts to feel “rough” to the touch, it is time for another coat.
With wooden planters and flower pots, it is mainly the outer, sun-exposed sides that need renewing. The inside of good-quality pieces is usually protected by a liner, so it only needs occasional attention.
4. Watch out for sun and moisture together
Paradoxically, it is not the sun alone that harms wood the most, but its combination with moisture. A summer storm makes the wood swell with water, the midday sun then quickly dries and shrinks it – and it is this repeated “breathing in and out” that tears the surface into cracks. That is why drainage matters for everything that stands outside: planters need holes in the bottom or a saucer, and decorations should not be left standing in puddles or on a wet railing.
The same rule applies to raised beds – regular watering is fine, but the structure should never stand in water permanently. Good drainage of the soil protects not only the plants, but also the wood itself.
5. Clean and check regularly
Summer air is full of pollen, dust and, after storms, muddy splashes. This thin layer holds moisture and speeds up the ageing of the surface. So every few weeks, wipe the wood with a damp cloth or sponge, or wash it with lukewarm water and a drop of mild soap. Do not use harsh cleaners or a pressure washer – a strong jet of water tears the fibres and opens the way for moisture.
While cleaning, take a good look at the wood. Small cracks, greying edges or spots where water no longer beads are a sign that it is nearly time for more oil. Acting early saves you a bigger restoration later.
6. Rescue grey or cracked wood with restoration
Even if the wood has already turned grey or rough, all is not lost. The grey layer is only on the surface, so you can lightly sand it with sandpaper along the grain, and healthy wood in its original warm colour will appear underneath. Carefully wipe away the sanding dust, let the surface dry and apply exterior oil again. The decoration will look practically new and regain its protection against further sun.
With deeper cracks, first check that the wood is not rotten. If it is sound, small cracks just need sanding and oiling; tighten the joints on assembled products if necessary. This “end-of-summer maintenance” is also ideal preparation before storing decorations away for the winter.
The most common mistakes to avoid: Do not leave wood with no surface finish at all in the southern sun all summer – bare wood turns grey the fastest. Do not use ordinary interior varnish on outdoor wood; in the sun it “works” differently from the wood beneath it and cracks. Do not oil wet or sun-heated wood – the oil will not soak in and will stay sticky. And do not underestimate drainage – a planter with no water outlet will fare worse than one in full sun with good drainage.
Frequently asked questions about protecting wood from the sun
Why does wood turn grey and crack in the sun?
Greying is caused by UV radiation, which breaks down the lignin in the surface layer of the wood. Cracking is mainly caused by the rapid alternation of moisture and dryness – the wood heats up in the sun, loses moisture and shrinks. Regular oiling and a suitable location prevent this to a large extent.
How often should I oil outdoor wood?
For decorations under normal exposure, it is enough to treat the surface at the start of the season and once during it. Planters and accessories in full sun can be oiled two or three times over the summer. The wood itself is your guide – as soon as the surface turns matt and stops repelling water, it is time for another coat.
Can grey wood still be rescued?
Yes. If the wood is not rotten, simply sand the surface lightly with sandpaper, wipe off the dust and oil it again with exterior oil. The grey layer is only on the surface, so healthy wood in its original colour almost always appears underneath.
Can I leave outdoor decorations outside all summer, even in the rain?
It depends on the type of wood and the surface finish. Products treated with exterior oil cope well with short spells of rain; the problem is standing in water for a long time. Planters therefore need drainage, and after heavy rain it is good to let the wood dry out. More delicate decorations are best brought indoors for the winter.
Are AMADEA wooden products suitable for outdoor use in the sun?
Our garden range in the Garden & Barbecue section – planters, flower pots and raised beds – is made for outdoor use and, with regular care, will last many seasons. Smaller decorations and accessories are better suited to a sheltered spot or a covered terrace. For every product made from local wood, a few minutes of maintenance a year will significantly extend its life.
🌳 Getting your garden or balcony ready for summer? At AMADEA you will find handmade wooden planters, raised beds and outdoor decorations made from Czech wood – built to last outdoors.
Browse the garden collectionAuthor: Martin Portych – specialist in wooden products, gift advice and shop content
Editorial policy: Our content is based on the day-to-day practice of the AMADEA shop, the real needs of our customers and a commitment to clear, useful and trustworthy information.