Everything you need to
plan your planter box
Planter panels come in six widths, at 400mm or 560mm high. Draw the outline of your planter in the Design Tool and it lists every panel, corner set and brace you need. Then take that list to your nearest stockist.
6
panel widths
400mm to 2m
2
heights
400mm and 560mm
1.2m
free‑standing
width per bracing set
1
finish
weathering steel
3
tools
drill, hammer and pliers
5,837km
steel sold
edging, beds and planters
Draw your planter, get the full parts list, then take it to your nearest stockist.
In their own words
What planter box buyers and landscapers say
Reviews from people who have built with Straightcurve, word for word from Trustpilot.
Jason Chalker
Trustpilot review · Australia
Great product, looks amazing in all shapes and sizes. Goes together easily and saves a lot of time with the ease of use of this product.
5★
Trustpilot review
Natasha Riley
Planter box buyer · UK
Superb brand to deal with, the team were very helpful when we needed advice and when we made a mistake with our order they got the additional parts out ASAP for us. It arrived very quickly and was really easy to assemble.
5★
planter review
Nick
Trade customer · Australia
Their products are literally very quick to put together and certainly look great when finished. I have used the 560mm, 400, 240 and 150mm flexline with great results and will be trying out their 560mm planters next week on a new job.
3
bed heights used
Real gardens
See planter boxes in finished gardens
These are real projects built with Straightcurve steel. Click any garden to see the panels, height and finish that were used. Square and rectangular planters can be drawn in the Planter Box Design Tool. Round planters and tree rings are made from Flex raised garden bed panels.
Ferny Hills, QLD
2 years old
Floating Concrete Steps Through a Native Garden with Weathering Steel
Perth, WA
7 years old
Cluster of Round Weathering Steel Planters at Different Heights
Canberra, ACT
2 years old
Matched Weathering Steel Cubes with Frangipani
Victoria
2 years old
Bottle Tree in a Round Weathering Steel Bed Beside a Timber Deck
Weathering Steel Planter of Flowering Aloes and Yuccas
Victoria
2 years old
Young Magnolias in Round Weathering Steel Planters Along a Lawn
Perth, WA
8 years old
Square Weathering Steel Planter with a Silver Shrub
Victoria
2 years old
Grass Tree in a Round Weathering Steel Planter
Central Coast, NSW
1 year old
Herb Garden in Weathering Steel Planter Boxes
Seen one you like? Draw your own in the Design Tool.
Installation videos
Watch a planter box go together
Three videos on planning a custom planter, joining the panels at each corner and bracing a tall box so it keeps its shape when it is full of soil.
3
join sets
straight, corner and reverse
90°
corner sets
reverse sets make L and U shapes
3
bracing options
cross brace, universal set or posts
Living material
How weathering steel changes on your planter boxes
Weathering steel, often called corten, arrives dark and builds a rust-coloured patina through ordinary wet and dry weather. That patina slows further corrosion. On a planter box every side stands above the ground, so you see the full change on each face.
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The Raw Starting Point
Dark, near-black surface from the mill-scale oxide layer. Each panel may vary slightly in tone. This evens out as the patina develops.
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Breaking Through
Orange patches appear as the mill-scale breaks down. Development may be uneven initially, particularly on faces with different weather exposure.
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The Orange Phase
The full surface transitions through shades of orange. Against green foliage and fresh soil, this phase is particularly striking.
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Warming and Deepening
Reddish-brown tones replace the brighter orange. The patina builds its protective density. Adjacent panels converge in colour.
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Finding Its Character
A deeper brown develops. The surface becomes increasingly uniform. The protective layer is well established.
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Rich and Stable
Deep, rich brown tone. The patina is stable and self-protecting, and asks very little of you. A quick rinse and an occasional check are all most gardens need.
Coastal conditions
Within about 2 km of the sea, airborne salt speeds up corrosion and makes it hard for the patina to form. Weathering steel can still be used near the coast with good drainage, gravel rather than mulch against the steel, and regular checks, as set out in our Product Care Guide.
Inland climate
Inland, ordinary wet and dry weather builds the patina, usually over the first 6 to 12 months. That layer slows further corrosion, and good drainage helps it keep working.
Downloads
Technical resources
The catalogue, and our two guides on how weathering steel lasts and how to look after it.
Product Catalogue
The full Australian range: heights, profiles, finishes, specifications and what comes in each box set.
Longevity Guide
What decides how long weathering steel lasts, from distance to the coast to drainage.
Product Care Guide
Practical guidance on looking after weathering steel products for the best possible patina development.
Visiting a stockist
What to expect when you visit
You have seen the gardens and watched the videos. A visit is where you get to handle the product and settle the questions that are hard to answer on a screen.
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Try it yourself
Ask them to open a ClickConnect™ box. Push two lengths of ClickConnect™ edging together until they click, bend a Flex length by hand, and run your finger along the rolled top edge. You have seen how easy it is in the videos, and this is where you find out for yourself.
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See it at full size
Stand next to a full-height raised bed panel and feel the weight of the steel. The height and thickness are much easier to judge in person than in a photo.
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See both finishes as they arrive
Weathering steel arrives dark grey and builds its rust-coloured patina over the following months. Galvanised steel arrives silver and stays that way. Seeing them side by side makes the choice easier.
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Talk through your project
Ask the team for advice on which product profile, height or finish would best suit your project, based on factors such as your soil type, slope angle or proximity to the coast. They can also check your quantities, so you leave with the right number of sets, corners and accessories.
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Take it home today
If your products are in stock you can start the same day, and pick up the soil and mulch on the same trip.
Before you go
Four things to do at home, so the visit is quick and the advice fits your garden.
Measure the space
Measure each run in metres and note the curves and corners. For raised beds, choose a height: 240mm, 400mm or 560mm.
Call ahead
Stock varies between stockist locations. Call ahead to check they have your preferred products or can order them in. You can find your nearest stockist's contact details on our Nearest Stockist page.
Photograph the spot
Photos of the area, the soil and anything nearby, such as paving, a fence or a slope, help the team advise you.
Check what is underground
Edging spikes and bracing go into the ground, so find out where pipes and cables run. Before You Dig Australia is a free service.
Material comparison
Steel planter boxes compared with timber, fibreglass and plastic
| Feature | Straightcurve Steel | Timber | Fibreglass / Plastic |
| Size and shape | Any straight-sided shape you can draw, from panels 400mm to 2m wide. Draw yours in the Design Tool |
Custom sizes mean cutting and building it yourself, or paying someone to. | Moulded in set sizes, so you choose from what is made. |
| Strength when full | Steel panels braced across the box, so the sides stay straight under wet soil. See the bracing options |
Sides can bow outward as wet soil pushes on them and the timber softens. | Thin walls can flex when full, and a light empty pot can tip in strong wind. |
| Base and drainage | Bottomless, so water drains straight out. On paving or a deck, line with geotextile and sit it on packers. | A timber base holds water and is usually the first part to rot. | Drainage depends on the holes moulded into the base. |
| Getting it into place | Flat-packed panels carried in through a side gate or doorway and assembled where it will stand. | A built box is heavy and hard to get through a house or side gate. | A one-piece planter has to fit through every gate and doorway on the way in. |
| How it looks over time | Weathering steel builds a rust-brown patina over the first months. How weathering steel changes |
Turns grey and splits unless it is stained or oiled regularly. | Colour can fade and the surface can go chalky in strong sun. |
| Growing food | No treatment chemicals in contact with the soil. Growing vegetables? See raised garden beds |
Treated pine can leach preservatives, so check the treatment first. | Depends on the plastic, so check it is rated food safe. |
| Looking after it | A rinse and an occasional check. Read the Product Care Guide |
Needs re-staining or oiling to keep its condition. | Little care, but it is replaced once it cracks or fades. |
A planter box usually sits somewhere everyone sees it, such as by the front door, on the patio or around the pool. Before you choose a material, check how you will get it into place, what it will stand on and where the water will drain. For more ideas, read our guide to planter box ideas and the answers to common questions about weathering steel. The Longevity Guide explains how the steel performs in Australian conditions. When you are ready, draw your planter and take the parts list to your nearest stockist.
Good to know
Questions to answer before you buy a planter box
The questions people ask us most before they order a planter box, from choosing a size and height to what it sits on and how it is braced.
Can I get a planter box in my own size and shape?
Yes. Our planter panels come in six widths, from 400mm to 2m, and join at straight runs, 90° corners and reverse corners. That means you can build squares, rectangles, L-shapes, U-shapes and stepped layouts to fit the space you have. Draw the outline in our Planter Box Design Tool and it works out every panel, corner set and brace you need.
What heights do steel planter boxes come in, and which should I choose?
Our planter boxes come in two heights, 400mm and 560mm. The 400mm height suits patios, courtyards and lower plantings. The 560mm height gives more soil depth for shrubs and small trees, and brings the planting closer to working height, so there is less bending. If you are growing vegetables and want even more choice of heights and shapes, look at our steel raised garden beds.
Do Straightcurve planter boxes have a base?
No. The planter boxes are bottomless. On soil or lawn, the planting connects with the ground below and drains naturally. On paving or concrete, sit the planter on packers so water can get out underneath, line it to hold the fill, and leave a clear way for water to drain. The Product Care Guide explains how to set it up.
Can I put a planter box on paving, a deck, a balcony or a rooftop?
Yes. The planter boxes are free-standing, with an optional bolt-down for a permanent fix to a hard surface. Raise the panels slightly on packers so water does not sit between the steel and the surface. On a balcony, deck or rooftop, check first that the structure can carry the weight of the planter once it is full of wet soil. Our bracing options show how to anchor on hard surfaces.
How do the panels go together, and what tools do I need?
Panels join with connector sets that come with the joins: straight join sets for long runs, corner sets for 90° corners and reverse corner sets for L-shapes. You screw the top and foot pieces in with a drill, shape the corner strip with pliers and hammer the wedges in at the back. There is no welding. Watch a corner go together in our installation videos.
Will the sides bow out once the planter is full of soil?
Not when it is braced correctly. A bracing strap set (FHL-BS) ties opposite sides together where they are up to 1200mm apart, so the box holds its shape on its own. For wider planters, use the Universal Bracing Set, and long 2m panels need extra support. Fit the bracing before you fill. See all our bracing solutions.
Which finish do the planter boxes come in?
Our planter boxes come in weathering steel, similar to COR-TEN. It starts dark and builds a rust-brown patina over the following months. If your planter is near the coast or a pool, read the Longevity Guide first, because salt and pool chemicals make it harder for a stable patina to form. Our common questions about weathering steel explain how the patina develops.
Is a corten planter box the same as a weathering steel planter box?
People often search for corten planter boxes. COR-TEN is a trademarked brand of weathering steel. Our planter boxes are made from weathering steel, similar to COR-TEN, which forms the same kind of rust-coloured protective patina. The patina slows further corrosion, but no COR-TEN or weathering steel is completely rustproof. Good drainage and keeping mulch and wet leaf litter off the steel make the biggest differences, as the Product Care Guide explains.
Can I grow vegetables and herbs in a steel planter box?
Yes. The steel has no treatment chemicals in contact with the soil, unlike treated pine. Before you fill it, you can paint the inside face of the panels with bitumen paint for extra protection, which is worthwhile in wet climates and on acidic soils. For a larger vegetable garden, our raised garden beds give you more shapes and three heights.
What should I fill it with, and how do I look after it?
Use gravel, pebbles or coarse sand against the steel at the bottom and sides, and make sure water cannot pool inside the planter. Keep mulch and other organic material from sitting against the steel. After that, a rinse and an occasional check are all most planters need. The Product Care Guide and Longevity Guide explain what makes the biggest difference to how long the steel lasts.
Can I get a round or curved planter?
Not with the straight planter panels. For round planters and tree rings, use our Flex raised garden bed panels, which you bend into a circle by hand. Two Flex panels make a circle about 1.4m across, and we also sell pre-made rings, so ask your nearest stockist about them. See how in our raised garden beds range, or get ideas from our guide to planter box ideas.
Is it made in Australia?
Straightcurve is owned, designed and engineered in Western Australia, where the company started over a decade ago. Our products are manufactured to our designs in Shanghai, China, to the highest ISO standard. As a result, Straightcurve is the highest-precision product in landscaping steel. This also allows us to distribute globally with greater efficiency, furthering our wider mission. Every batch of steel comes with a test report covering strength, thickness, coating weight and composition, and the Longevity Guide explains how that steel performs in Australian conditions.
What do I buy, and where do I get it?
Use the Planter Box Design Tool. Draw the outline of your planter and it lists every panel, corner set and brace you need. Take that list to your nearest stockist, where you can see the steel in person and buy everything you need. Stock varies between stockists, so call ahead to check they have your products. If you would like to see prices first, request our price list. Landscape professionals can apply for a Trade Account to access trade pricing, build product quotes and use our technical trade resources.
BEYOND THE GARDEN
The Ignition Chamber
Straightcurve is part of The Ignition Chamber, an Australian company that builds vertically integrated climate infrastructure companies. Each one funds what comes next.
Circular Design
Zero plastic packaging
Two years of R&D replaced every piece of foam and plastic with waterproof cardboard and compostable tape.
Carbon Capture
Essier bamboo decking
Bamboo boards that are 60% carbon negative, returned at end of life for permanent underground storage.
Climate Housing
Elysium Living
Homes designed to be carbon negative to build, energy positive to live in, and globally deployable.
Why a garden company builds houses
Straightcurve was the first company built inside The Ignition Chamber. The lessons from scaling it across seven countries are now being applied to carbon-negative housing.
Straightcurve started with a redesign of steel garden edging. No welding. No specialist tools. Professional results from a single modular system. But scaling globally meant confronting harder questions. Weathering steel corrodes over time. Packaging depends on plastic. Two years and hundreds of thousands of dollars later came protective coatings developed to help the steel last longer, and cardboard waterproofed with organic oil instead of plastic film. The same perseverance produced Essier, bamboo decking that is 60% carbon negative; and Elysium, housing designed to remove carbon from the atmosphere. Each company funds what comes next.
Start today
Ready to plan your planter box?
Draw your planter in any size or shape, then take the parts list to your nearest stockist. Home gardeners and landscapers have already put more than 5,837 km of Straightcurve steel into their gardens.
