Choosing a garden bed material can be confusing – every material has its own benefits and drawbacks. That said, galvanized steel is a clear winner for many people, as it offers the most extended lifespan of all raised bed materials and comes with a clean, stunning appearance.
Galvanized steel raised beds will last at least 30 years, but they can last over 120 years depending on the climate, the quality of the steel, and the acidity of your soil. Overly humid, acidic soil can wear away the zinc plating on steel beds, leading to rust and deterioration.
So, let’s discuss the longevity and practicality of galvanized steel garden beds. I’ll tell you more about how long these beds last, the pros and cons of going with steel, and tell you more about the safety and other concerns surrounding galvanized steel raised beds.
Do Galvanized Steel Garden Beds Rust?
Galvanized steel garden beds rust, but only if the zinc plating on the steel wears away. The main factors that impact how long a galvanized steel garden bed will last before rusting are the thickness of the zinc plating on the steel, the humidity in your garden, and the acidity of the soil.
Galvanized steel usually consists of steel sheets coated with zinc. Zinc does not corrode, so this plating ensures that your garden beds don’t rust and crumble away.
However, over time, the zinc may destabilize, chip, or wear down, leaving the steel sheets in your garden bed exposed to moisture, air, and the chemicals in your soil. This process directly determines the lifespan of your raised bed. Naturally, it’ll take longer for a thick zinc plating to wear away than a thinner one, so quality matters when choosing a steel garden bed.
Once the zinc has worn away from your steel bed, rain, soil moisture, and acidic chemicals such as salt, vinegar, and acidic soil amendments can expedite the rusting process. This leaves holes and unmanageable rust spots in your raised bed.
Depending on the quality of your garden bed, the soil conditions, and the thickness of the zinc plating, it can take anywhere from 20 to 100 years for rust formation. However, once the rust takes over, your garden bed likely only has a few years left.
To compensate for the lifespan of galvanized steel beds, some garden bed manufacturers apply plastic, aluminum, or enamel paint coatings to the galvanized steel.
Although these garden beds come at an extra price premium, they are incredibly long-lasting. However, if you get one of these high-quality models, you won’t have to replace your bed or negotiate with rust for at least 50 years.
Is Galvanized Steel Safe To Use for Garden Beds?
Galvanized steel is safe to use for garden beds. While galvanized steel usually contains zinc, a potential toxicant, the zinc will not leach into the soil unless your soil pH is lower than 5.5. This pH is unsuitable for plant growth, so garden beds rarely reach this level of acidity.
Some people worry that the zinc coating on galvanized steel will leach into a garden’s soil, where edible plants such as vegetables will absorb the mineral. While the zinc may mobilize and enter your soil, it is not toxic, and it takes special conditions for the zinc to peel away from your steel garden bed.
According to research and many reviews, zinc is not toxic unless you ingest large quantities. Zinc is one of the minerals commonly included in daily multivitamins and dietary supplements, and it’s a necessary micronutrient that helps us replicate DNA and form new cells. So, zinc is healthy if you do not consume too much.
Luckily, the zinc in galvanized steel garden beds is not “mobile.” This means that the zinc plating is relatively secure and has chemically bonded with the steel. Acidity is the only thing that interferes with this chemical bond (and therefore moves the zinc into your garden’s soil).
Highly acidic chemicals such as vinegar may destabilize the zinc plating, causing it to leach into your soil. As this takes place, it leaves the steel exposed to the air, allowing rust to form. So, these acidic conditions aren’t just bad for the zinc plating but will also decrease the lifespan of your raised bed.
However, plants do not grow well at the acid levels that destabilize the zinc plating. So, if your garden bed’s soil was acidic enough to release the zinc into your garden, it’s likely that your plants would die from the exposure to acidic conditions before any zinc dissolved into the soil.
You don’t need to worry about a zinc overdose with a galvanized raised bed – just don’t pour raw vinegar or pickle juice into your garden.
If you are thinking about growing vegetables in galvanized steel beds, I recommend reading my other article. I’ll explain why it’s safe to use galvanized steel to grow food and what you need to look out for: Is It Safe To Grow Vegetables in Galvanized Tubs?
Is Galvanized Steel Good for Raised Garden Beds?
Galvanized steel is good for raised garden beds. Galvanized steel is durable, rust-resistant, and chemical-free, and it can help you keep your garden as low-maintenance as possible for many years to come.
In my opinion, it’s hard to find a better material for raised garden beds than galvanized steel. However, galvanized steel isn’t the best choice for everyone, so let’s look at the pros and cons so you can weigh out your options and form your own opinion.
- They last many years. Steel lasts an incredibly long time compared to other materials, such as plastic and wood. Steel garden beds last three to eight times as long as wood beds, so it’ll save you the effort of rebuilding and repairing your raised beds.
- Steel keeps out pests and weeds. Steel is tough, which means that weeds and pests can’t climb into them through the soil. So, these beds offer chemical-free, organic pest and weed control, eliminating the need to use herbicides and pesticides to keep your garden healthy and vibrant.
- Steel ensures that your fertilizers don’t wash away. Whether you worry that your garden fertilizers will interfere with the ecosystem in your garden, or you want to preserve that precious compost you’ve spent years preparing, steel beds have got you covered. Since steel beds are rigid and have no holes in the top, they’ll keep your fertilizers and soil from running off.
- They look fantastic. Steel beds look clean and slightly industrial, adding a lovely contrast to your landscape. These beds make a true aesthetic statement and can make any garden look more well-cared for and organized.
- They can be almost any size or height. Steel beds come on legs or not, and you’ll find them in sizes ranging from tiny pot-sized planters to giant troughs. With such a wide variety of shapes and sizes (and the ability to easily customize), you’re sure to find steel beds that fit all of your needs.
- They are organic-safe. Since galvanized steel does not contain chemicals, preservatives, fungicides, or pesticides, it’s entirely safe and appropriate for organic gardening. The other most popular garden bed materials – plastic and wood – are rarely safe for organic gardening.
- It is challenging to allow for ample drainage. Because metal traps moisture, steel can inhibit your garden’s drainage. However, it won’t be too bad since steel beds usually have large holes or mesh in the bottom (or don’t have a base) to ensure that the excess water runs away.
- They can get very hot. Since steel is a thermal conductor, it can get hot under the sun’s heat, drying out your soil and potentially reflecting too much sunlight onto your garden plants. So, steel beds do best when you plant other plants around them to block some of the sunlight from the metal.
- They are costly. Steel beds are much more expensive than most other options, such as plastic or wood. However, you won’t have to worry about chemicals leaching from the bed into your soil with steel, and steel lasts many years. Ultimately, a steel bed is worth it if you can afford the initial investment.
Galvanized steel garden beds will last at least 30 years, but they can last much longer if you purchase a high-quality model with thick plating and protective coatings of paint, plastic, or aluminum. These beds are incredibly safe for garden beds, cost-effective, and easy to maintain, making them ideal for any gardener.
Of all the garden beds I’ve tried, galvanized steel is my favorite since it is versatile, chemical-free, and long-lasting. So, give them a go, and see what you think. I think you will be pleasantly surprised for many years to come.