There are so many options when it comes to raised bed garden materials that it could make anyone’s head spin. When you’re deciding how to build your garden from the ground-up or how to make additions to an established garden, you want to go into the planning process informed and aware. The following content also has some reference value for raised garden beds.
The truth is that there is no perfect material on the market. When you decide to create raised garden beds, you have to weigh your options based on the conditions of your region and, more specifically, your garden. There are garden bed kits you can buy, but too many options can lead to confusion.
That’s why we’ve developed this piece that helps you organize your thoughts around which raised bed materials are best for you and your situation. We’ll discuss each material and the advantages and disadvantages of each based on regional and financial factors, as well as how difficult the materials are to work with.
Now, let’s talk about raised beds of all kinds!
Metal raised garden beds are made of different steels that are sometimes sold in a kit, and sometimes put together from reused corrugated steel. You can build raised beds from cheaper reclaimed steel, corten steel, or powder-coated steel. Some are expertly crafted for durability, while others aren’t as good.
Epic Gardening sells metal raised beds made by Birdie’s, which are the best metal raised beds on the market. You can find Birdie’s beds in our online store. But before you spring for them, let’s discuss their use in organic gardening.
Advantages of Steel Beds
Steel beds have thin sides that take up less space in your yard, garden, or field. They won’t take up as much as a wooden bed will. In particular, steels that are made of alloys are designed to last a long time. While there’s a lot of talk about how heat is bad for steel raised beds, this isn’t a concern. Steel beds can hold up to both hot and cold conditions and don’t experience significant temperature changes over other types of raised garden bed materials.
You might think steel raised beds aren’t cost-effective, or wonder if their longevity doesn’t match their price. However, the cost of lumber often makes metal beds more affordable, and they last much longer. A good powder-coated galvanized steel or corten steel bed lasts for at least 20 years due to varying coatings, whereas a wood bed generally doesn’t even last 15 years.
As for the actual cost, you’re likely to find some variability between distributors. They hold garden soil well, and unless there is some chemical imbalance, such as high salinity or chemical contamination of the soil, they hold up for decades. This makes them one of the best materials for raised beds today.
Most steel beds (save plain galvanized steel) come in a kit and are easy to build, requiring no power tools and no need to drill pilot holes. This is the case for all Birdies beds. Conducting maintenance on the beds is easy too! There’s very little you need to do to keep them up, and they can be disassembled and transported easily.
Disadvantages of Steel Raised Beds
Galvanized steel beds that lack a coating or treatment, like repurposed stock tanks, won’t last as long as other coated or heat-treated beds will. They are prone to rusting out over time, meaning stock tanks won’t last as long as a wooden bed. They are exceptionally cheap, but chemicals from the manufacturing process may leach into garden soil and end up in food crops.
A more acidic soil mix or peat moss-heavy blend will corrode these beds faster. Therefore, unless you’re ok with replacing them after less than a decade, it would be better to go with a more sustainable material. Constructing a bed from repurposed galvanized steel can be a chore sometimes and may require more than one person to execute.
It’s worth noting that corten steel beds can also deteriorate and stain the surface they are placed on. However, this doesn’t cause any harm to the surrounding environment, nor is the staining irreversible. You can place the corten planter or bed on a draining tray, or divert the runoff away from your concrete surface. Pressure washing the concrete every now and then should also remove the staining.
Before we get into the pros and cons of wooden raised beds, let’s discuss types of wood. Hard wood holds up longer than softer or composite wood. Most wooden raised bed guides recommend using cedar lumber that has been treated to withstand the elements. You can also use oak, pine, fir, cypress, and redwood to build beds. Factors like cost and availability will come into play when you decide what to build.
Advantages of Gardening in a Wooden Raised Bed
Wood is sometimes a cheaper and more aesthetically pleasing choice for a natural garden setting. Especially if you’ve located a good source of non-pressure treated wood that is made of high-quality materials like douglas fir, cedar, or redwood, both you and the garden benefit. Raw materials that don’t contain chemicals can even be reincorporated into other projects after you’re done using them as raised beds.
Upcycled wood isn’t hard to find for building a raised bed. The modularity involved when you build a raised bed out of wood means backyard gardeners have complete creative control. Adding soil annually can be as difficult or as easy as the design allows.
Disadvantages Associated With Wooden Beds
Treated wood may hold up for longer, but untreated wood could be better for a food crop garden. There are plenty of stains and sealers out there that are designed to be used to fortify wood garden bed materials. However, there are plenty of raised bed kits that contain treated wood that might not be safe for growing food.
Pressure treatments are sometimes advertised as safe for garden beds, but that’s not always the case. Avoid those treated with chromated copper arsenate, as they leach into the garden bed and into the area where you grow food. Untreated wood may be an easier option to build a raised bed overall, but this means your wood will rot faster than a sealed or pressure-treated bed.
So while wood is one of the best materials for raised beds, finding the right rot-resistant woods can be difficult. Acquiring wood at an affordable price is also difficult these days. If you choose to use recycled wood, you could run into rot issues even faster than you would with new pressure-treated wood. The difficulty of building the bed is high compared to other materials too.
Brick and Concrete Beds
Reused brick, cinder block, concrete block, and concrete planters are all viable options as raised bed materials. You can lay bricks in the appropriate fashion, and have a raised bed in no time. You can go one step further and mortar or cement the beds together. There are even kits that come with wood paneling and concrete corners.
Brick, Cinder Blocks, or Concrete Bed Advantages
Bricks and concrete blocks are very easy to find. People get rid of them all the time on resale websites, and they’re widely available in big box stores. You can easily design whatever size and shape of raised bed you want too. When it comes to modular building materials, you’re working with one of the lowest design difficulties with bricks and blocks.
One really awesome thing about brick is that it withstands cold best of all the materials we mention here. It holds the most heat, especially when you work with a good quality brick. Older, antique bricks tend to be made of stronger materials, standing up to the elements longer. This means it’s possible to work with reusable materials when you choose bricks.
Disadvantages of Brick or Cement Blocks as Raised Garden Beds
One of the main concerns involved with cement blocks and cinder blocks is that concrete can be toxic. That means not only could the concrete leach into the surrounding soil of your front yard garden, it can also leach chemicals into food crops. Concrete blocks of all kinds are made with fly ash, which is an aggregate used in their manufacture. This aggregate contains heavy metals and other materials unsuitable for growing food crops or plants in general.
Not only could they be toxic, but all of the materials in this section are heavy and may be difficult for one person to set up by themselves. For those who use equipment to be mobile in their gardens, this may not even be an option due to the heft of each brick or cinder block.
Poor-quality bricks can crack easily in cold, wet environments. So can concrete, cinder block, or cement materials. This issue thwarts their rot-resistant capabilities. While they won’t rot like cedar or redwood, they may not last as long in certain environments, meaning the effort you made could be thwarted within a couple of years.
Frequently Asked Questions
Q: What is the best material to make a raised garden bed?
A: High-quality galvanized raised beds with a coating or a long-lasting wood like cedar are best.
Q: What is the cheapest material to use for raised garden beds?
A: Concrete blocks or cinder blocks are the cheapest raised garden bed materials available.
Q: What do I put on the bottom of a raised garden bed?
A: Unless you’re working on a slope or on concrete, you don’t need to line the bottom of the bed. Leaving it open to the native soil allows the soil microbiology to freely spread through your raised bed soil.
Q: What should raised beds be made of?
A: Use the raised garden bed materials that work best for your garden’s needs. Consider your financial, physical, and spatial capabilities, and go from there!