Corten Steel: A longer lasting, more modern alternative to wood raised gardening beds
We completely- from scratch- designed and built the backyard this winter. Yes, winter. In January Chris and I started the important but not fun process of building fences and walls pouring concrete, and moving eight tons of gravel. But then we got to the fun part: the garden. Our kitchen garden, a mini potager if you will, is a series of Corten steel raised planters and it has been a great decision this season.
What is Corten Steel?
Corten steel (aka Cor-ten) is ‘weathering steel’. This trademarked name is a group of steel alloys that create a special finish on metal.
Why we used Corten Steel raised beds instead of wood
In the long run, Corten Steel was a better investment than the ‘correct’ wood you should be using in edible gardens.
Pressure treated wood, the stuff that resists degradation of weathering, is filled with chemicals. It’s literally soaked in chemicals (that’s its job!). And we don’t want that soaking into the soil we’re using to grow food. The same goes for those ‘fun DIY’ gardens where people like to use old railroad ties. Which are soaked in creosote. Which you also don’t want in your soil.
Pressure treated wood has its place. That’s why we used it to build a fence and retaining wall for our non edible garden. With that said, we also took time to line the back of the retaining wall so the soil wouldn’t directly come in contact with the dirt.
The bottom line being, the only wood you should really be using that would last a long time for an edible garden is cedar. That shit is EXPENSIVE. And eventually you do have to replace it. We ended up calculating it out that really buying Corten Steel beds would mean spending less in the long run.
You never need to paint or seal Corten since a stable rust-like look is naturally formed after several years, completely resists corrosion. (the problem with using metal outside) and you never need to worry about rain, snow, humidity etc. It’s completely resistant to frost and cracking that can happen in colder climates.
But after all that practicality…they look amazing. Chris and I describe our backyard as ‘controlled lush’. We like a ton of plants that combine and overlap and grow like crazy, but we also want modern, clean lines. Corten steel was the perfect linear, modern balance to other choices we made in the yard.
What planters did you buy?
For a longer, narrow space, we purchased 3, four by four foot square Corten steel garden planters and put them immediately next to each other to form a rectangular but segmented bed. We looked at multiple websites but this one was the best price by far.
This company also sells corner raised planters if you choose to create walkways between your beds which, in the long run, would be my goal with a larger yard. (PS you can totally move these with you from house to house).
Does it go through an ugly phase with the oxidation process?
You might fall in love with the look of the product right out of the box. It’s a pretty warm metal look. I mean, I liked it! But it does get ‘better’ looking with time and if you look at photos on Pinterest of well developed gardens, you’ll typically find these planters. They don’t stand out and scream ORANGE, just modern natural vibes. They’re used at the Highline in NYC and a ton of other architecturally driven locations.
It takes different amounts of time in different climates but in general the more wet to dry moments that happen, the faster it tends to go.
In these photos you’ll notice the tops of our beds have oxidized looking ‘scratches’…it’s because we originally put them the other side up…so that’s wet grass! Those are grass blades. We could sand them off and give it a fresh start, but I think it looks totally fine.
What dirt did you fill your raised beds with?
The base of these planters is totally open, meaning full drainage. Good drainage is crucial for plants, so take stock of what kind of soil your yard has before you make decisions. We wrote a garden 101 post on how to find out your soil type and how to decide what to plant.
We filled the beds with a blend of garden soil, compost and soil conditioner. It’s totally from scratch, no yard dirt to ensure no lead paint chips etc were in the soil we were growing food in. Since our house is over 100 years old..lead is just around. From there, we did a rough square by square planting method, planting items that had similar needs with each other together (basil and tomatoes and marigolds).
Did you use Preen or landscape fabric under your raised beds?
We have been asked this several times. No and no. Preen (a product that prevents weed germination) just was never part of my gardening or Chris’s gardening experience. We also chose not to use landscape fabric since we wanted to make sure worms could come up from the yard into the beds. Worms are super important for soil health.
How do you maintain your raised kitchen garden beds?
The steel requires no maintenance so it’s just about weed control, watering and fertilizing the plants inside! Most days, I spend ten minutes outside weeding, cutting off dead leaves, training tomatoes to the cedar trellis that Chris built and checking on plaint health. For the areas between plants I like to use a hand held hoe/cultivator tool to fluff the dirt and make sure nothing is trying to grow between them that shouldn’t be. And between the two of us, I think it makes the dirt look dark and clean and pretty.
Dietitian Nutritionist. My husband Chris and I create food and beverage photos, videos, stopmotions and recipes. And they're really cool.