Shiny, lustrous, rusty or painted, metals can be used both structurally and decoratively in your garden. Here are some ideas on how to use and care for different grades of steel, as well as aluminium, zinc, brass, bronze and copper.
1. Be careful how you mix your metals
There are some metals that you just can’t mix as they will start to corrode where they touch, especially if they get wet. This happens because when two different metals touch and a slight current can flow between them, using water as a conductor. Some metals are called ‘active’ or sacrificial metals, like aluminium, carbon steel and zinc. These will corrode if they’re put with a ‘noble’ or passive metal like copper, nickel or titanium. This becomes really important when you’re choosing fastenings for something metal outside where it’s likely to be regularly wet from either rain or condensation, especially in salt-affected zones. This process, called galvanic corrosion, means you need to match your fastening screws and bolts to the main metal. Combinations to avoid include water running off copper onto zinc-coated steel, or using aluminium rivets in steel. Steel fastenings that have been galvanised, which uses a zinc coating to protect steel from rust can corrode quickly in stainless steel (especially the higher grades) as stainless steel has a percentage of chromium (a noble metal) and a bigger surface area, generating more corrosive current.
2. Using weathering steel in your garden
Weathering steels, which is often called COR-TEN steel, are steel alloys which develop a stable rust coating on the surface that will not continue to rust away like ordinary steel. Often used in outdoor sculpture and screens, thick weathering steel can also be used in other landscape applications like retaining walls and cladding. However if used where it is subjected to salt-laden winds it will eventually corrode, especially if water can collect in pockets. Be careful using weathering steel over pale coloured paving as water runoff can produce rusty stains.
3. The soft lustre of zinc
Zinc planters and statues became popular in Europe during the early 1800s as they could produce work with fine detail that was much cheaper than bronze and be gilded to look like gold. Zinc has lower embodied energy than metals such as aluminium (one quarter) and copper or stainless steel (one third) and it can be easily recycled. Zinc develops a beautiful soft bluish-grey patina as it ages, which protects it from corrosion. Replica (or real if you can afford it!) zinc French antique garden pieces such as tubs, house numbers and planters have a quiet and ageless appeal.
4. Copper water features and birdbaths
Copper is an excellent sculptural metal to use in the garden as its malleability means it can be easily bent and manipulated into beautiful shapes. Round pieces are often created while being spun on a lathe, producing ‘spun copper’. As it doesn’t rust, copper is ideal for water features and the patina that forms actually makes the metal stronger too.
Its thinness also means that the metallic ‘plink’ as water hits it can be used in waterfalls and fountains with very pleasing pitch combinations. The very smooth surface of a solid copper birdbath makes it super easy to keep clean and you’ll find also that mosquitos are not as attracted to water contained by copper. You can buy copper water features in a range of sizes and finishes like a soft autumn patina or green verdigris. Copper is also easily recycled so many decorative copper outdoor items are yesterday’s discarded scrap metal copper pipes and tanks.
5. Art from reused and recycled metal
DIY metal sculpture from found objects is very popular with gardeners. We don’t like to throw things away! With a bit of ingenuity and handiwork you can use old barbed wire to make rolled wire balls or even animals and birds, reuse discarded metal stamped and cut sheets as screens and garden decorations, and old metal containers as quirky plant pots. Even old cutlery can be recycled into windchimes and sculpture. Old rusting farm machinery can become a sculptural piece in the appropriate garden. Leftover steel reinforcing mesh can be meshed together to use as a light garden screen or rods fastened together for a climbing plant trellis. Old teapots and saucepans look quaintly cute when filled with a mix of colourful succulents.
6. Behold a blacksmith at festivals and classes
Blacksmithing is one of our oldest trades. Although not so common these days there are still blacksmiths in most cities creating bespoke wrought iron fences, gates, lights and sculpture. Most countries have an annual blacksmith festival or you can contact a guild of blacksmiths to find out about classes, workshops and demonstrations. In Australia, there’s Melbourne’s Waterside Metal Art Studio and also the fabulous annual Ironfest every April in NSW. In the UK there’s the National Heritage Ironwork Group and the British Artists Blacksmith Association. The USA has the Fire on the Mountain Festival in North Carolina in April, and you can contact the Northwest Blacksmith Association in Washington. For blacksmiths around the world go to the FeBlacksmith site for a list of guilds and associations.
7. Bronze – does it make the best sculptures?
Many of us have lusted after an original bronze sculpture for our gardens. Bronze is an alloy metal of mostly copper with tin, although it can also have small amounts of other additives such as silicon or aluminium. It’s longevity is well recorded with some of the oldest art in the world made from cast bronze.
There are several significant advantages in choosing a bronze sculpture. First, it won’t ever rust, even in a seaside location. Second, it lasts pretty much forever and won’t chip, crack or shatter, even in icy climates. Third, it’s virtually impossible to damage. Fourth, as bronze ages its soft, lustrous patina just gets better and better. Fifth, the ‘lost wax’ process of bronze casting means that your bronze sculpture can carry the most amazing detail so it looks incredible both from a distance but also close-up. Bronze has a most interesting quality – it expands just before it sets, forcing the metal into the tiniest parts of the mould, and then shrinks slightly as it hardens, so the sculpture can easily be removed from the mould without damaging that detail.
8. Brass in the garden
Brass is an alloy of copper and zinc producing a yellowish, lustrous metal that can be highly polished. Brass with a high copper content forms a protective oxide layer that prevents corrosion while the zinc gives it strength. Traditionally used for garden tapware, you can also find brass sundials, planters, bells, small statues, decorative handles and fastenings.
9. Choosing metal garden furniture – hot, or not?
Metal outdoor furniture can absorb or reflect heat more than most surfaces. This can be either a disadvantage or an advantage, depending on your climate, the amount of shade/sun and the season. In summer, heavy and dark coloured steel quickly heats up to skin-singeing temperature, so you need to keep this furniture for shady areas. Lightweight and reflective aluminium furniture stays surprisingly cool even in the summer sun but all metals outside in the colder months can chill you to the bone unless you bring out some thick cushions for both for the seat and back.
10. Choosing the right grade of stainless steel
There are several different grades of stainless steel, with the number descriptive of its corrosion resistance. 304 grade stainless steel has added chromium and nickel and is generally suitable for outdoor uses, while 316 grade has chromium but also higher carbon, nickel and added molybdenum to resist corrosion in salt-laden maritime environments. Stainless steel comes in a range of surface finishes such as mill, brush and mirror. If you’re going to work with stainless steel, then use a newly sharpened drill on a low speed and lots of lubricant, or cut it with a thin disk on your angle grinder. Otherwise, heat build-up from a blunt drill or thicker disk will harden the steel.
Outdoor stainless steel still needs regular washing with warm, detergent water to remove corrosive deposits. Drying will reduce smearing. Tea staining is small areas of brownish rust stains on stainless steel that don’t usually damage it but look ugly. Ask the manufacturer for a cleaning recommendation, which usually involves either nitric or sulphuric acid. Stainless steel near a pool is especially vulnerable to corrosion if the water is sanitised using either chlorine or bromine so wash it frequently with fresh water.
11. Metal screens in the garden
Metal screens are now not just for those who can afford something bespoke, with cheap laser-cut metal screens available at hardware stores from around $100. As they’re very thin you can use them to separate even a small garden into different areas, or create a private nook while still maintaining a good airflow. Mounted in front of a coloured wall or back lit at night, they also make a dramatic statement. Attach them to a strong steel framework for an attractive ‘peep-through’ gate. Whether you’re into circles, geometrics, flowers, traditional or abstract patterns you can find a screen to suit your style and in a range of metals such as aluminium, weathering steel, stainless steel, copper and brass.
12. Metal garden edging
Available in aluminium or steel and in a range of either natural metal or painted colours, continuous metal edging makes a crisp and narrow garden edging, so you’re not losing valuable planting space. Metal garden edging is flexible so you can use it in informal gardens along sinuous curves, or in more formal designs for circles, straight lines and squares. Choose metal garden edging that has a rolled top for extra strength and safety. Lighter weight aluminium edging is good for paths and garden beds and lawn edging and can be easily cut by the home handy person but if you want something more structural and retaining, use either steel or special heavy-duty aluminium rated for this purpose. Metal garden edging is available in depths between 50mm (2 inches) to 150mm (6 inches) making it very versatile.
13. Outdoor firepits and braziers
The ever-popular firepit is evolving into a variety of decorative metal braziers, chimineas and even hanging pods, which can be moved about for the best seasonal position. Some can even double as ice buckets for chilling summer drinks.
14. Preserving and repairing corroded metal
If you’ve got some old, rusting garden furniture or artwork, you can save it from further damage. Rust converters work by using tannic or phosphoric acid (the tannic acid often works better) to change iron oxide (rust) to a more stable blackish compound, which can then be painted over. Although you can use rust converters on decorative items, unfortunately you can’t use it to salvage structural steel, which you’ll will need to grind back to fresh metal and them re-prime. Wrought iron can be protected with rust-preventing wax.