Traditionally, raised garden beds were all made with wood, and occasionally brick and stone. But nowadays, you can find galvanized steel as a viable option for raised beds. Galvanized steel is an underrated material that has a host of benefits, but both galvanized steel and wood have their advantages & disadvantages.
Galvanized Steel Raised Garden Beds
There is currently a resurgence of interest in galvanized steel as a material for raised garden beds, with companies specifically manufacturing galvanized raised bed kits that are easy to assemble, safe to use, and are guaranteed to last longer than any type of wood. Galvanized steel beds are pricy, but offer the best long-term, low-maintenance solution for home gardeners.
Advantages of Using Galvanized Steel
Galvanized steel is zinc-coated steel which protects from corrosion, making it ideal for any outdoor applications. It can take years before it will start rusting, with galvanized beds lasting at least 20 years without needing replacements and with minimal maintenance.
Galvanized steel won’t rot, won’t degrade, and is extremely durable. While there is nothing stopping you from building taller raised beds out of wood, galvanized steel bed kits often already come in taller versions. Taller raised beds, around waist height, make it easier for planting, weeding, mulching, and harvesting, especially for older gardeners or those with mobility difficulties.
Disadvantages of Galvanized Steel
Going with galvanized steel beds seems like a no-brainer but there are costs to using galvanized steel.
The first is the cost: Raised garden beds made of galvanized steel have much higher upfront costs than their wooden counterparts. While a 12 sq. foot wooden raised bed made with readily available pine can cost less than $30 or can even be free using salvaged wood, a galvanized steel bed of the same size could easily run you more than $100, especially a heavy duty one.
Galvanized raised beds are not as easy to find as wood. Suppliers are far and few between, and scavenging your own galvanized steel often means getting steel that is already starting to rust. The one situation where galvanized beds won’t last as long is in acidic soil. Acid will gradually eat away at the zinc coating. Use plastic-lined galvanized steel if you are filling it with soil for acid-loving plants like blueberries.
Lastly, galvanized raised beds won’t do much to insulate the soil for winter gardening. Yes, galvanized steel will heat up faster in the sun, but it will also release heat more quickly at night.
Where to Get Galvanized Steel Beds
There are different styles of galvanized steel beds, but I would strongly advise against any galvanized raised garden beds that use plastic posts or fittings, as the plastic will degrade or break long before the galvanized steel.
Instead, look for all-steel designs or those with wood frames or posts. At least for wooden frames, they will be easier to replace over the lifetime of your raised garden beds.
Wood Raised Garden Beds
Wood is one of the world’s universal building materials and the most popular choice for gardeners worldwide - for good reason. It’s cheap and can be found anywhere. And although it doesn’t last forever, wooden raised beds can last several years before needing to be replaced.
Advantages of Using Wood
The advantages of using wood for raised garden beds are its price, customizability, and universal availability. They also boast some of the best thermal properties of all raised bed materials.
Wood, by far, is the cheapest raised bed material you can use. You can even salvage wood for free from people’s curbs, wood pallets, and even old furniture. And of course, you can source your own wood from a forested woodlot. But for most gardeners, you will source your lumber from the hardware store, and a wood like pine is very affordable, even to build a large raised garden bed.
Wood is extremely easy to source, no matter where you are: in the city, the countryside, or growing a survival garden in the middle of nowhere.
Wooden raised garden beds are very customizable. You can trim lumber to the exact size you want so you can build your raised beds according to your exact specifications. Galvanized steel beds, while they can come in different sizes, are still limited in the variety of sizes and shapes available.
Another advantage of wood, which is not often talked about, is how good of an insulator it is. Wood will insulate your soil far better than galvanized steel, which makes wood ideal for building raised beds with cold frames for winter gardening.
Disadvantages of Wooden Raised Beds
The main downside of using wood is that it doesn’t last as long as galvanized steel. This is especially true if you live in a humid or rainy climate.
Wood will rot over time and can also be eaten by termites or sowbugs. If you’re a DIY kind of gardener, this isn’t a problem as you can easily replace boards as needed. However, if you don’t want to fuss with your raised beds once you build them, you should consider galvanized steel instead.
Generally, unless you use cedar or redwood, expect your wooden raised beds to last up to 10 years.
Types of Wood for Garden Beds
Although wood can be one of the cheapest materials for a raised garden bed, it depends entirely on the type of wood you use.
Most gardeners will use untreated pine since they are so readily available and very affordable. The downside of using pine is that it won’t last quite as long as other types of wood. Untreated pine beds will typically last 7 to 10 years. However, if you live in a very humid climate, like the Pacific Northwest, or in the deep South, that could significantly shorten the lifespan of your wooden raised beds.
The most expensive but most durable choice is either cedar or redwood. Cedar is also widely available but can be very expensive. However, if you can source cheap cedar or are willing to pay more, expect your cedar beds to last 10 to 20 years.
For DIY raised garden beds on a budget, an option that has become popular recently is repurposing wood pallets. Often you can get pallets for free if you ask around various distribution centers, large stores, or even check local online ads. You can also find local pallet recycling centers which can give you pallets for free or for a small nominal fee.
If you use pallets to build wood raised garden beds, avoid any colored pallets or pallets with MB stamped on them. MB stands for methyl bromide, which is a toxic chemical used to treat wood pallets.
Wood pallets stamped with HT (heat-treated), DB (debarked), or KD (kiln-dried) should be safe for use in the garden.
Should I Use Galvanized Steel or Wood?
In the end, it really depends on your circumstances and budget.
If you have an unlimited budget, you will have good results with either cedar or galvanized steel. It’s all a matter of style. Some people prefer the rustic appearance of wooden raised beds while others like the industrial look and finish of corrugated galvanized steel.
For those on a budget, you can’t go wrong with wood. Wooden raised beds are easy to build and you can even salvage wood for free. Wood also allows for more flexibility of design and customizability.
If you live in a humid climate, galvanized steel offers a more durable, long-term solution.
Gardeners who don’t want to fuss with their raised beds or have mobility issues could also opt for galvanized beds, since they will last for decades and many are a standard 2-ft or 3-ft tall, making it easier to grow your vegetables and flowers.