Types of Raised Garden Beds and What’s Best

Raised garden beds offer many advantages from the traditional ground level planting strategies. They’re more ergonomic and keep weeds at bay much more effectively. Some are easy to setup and others make a bold statement on the backyard. In this article we will discuss the pros and cons of each style of raised bed and make some suggestions along the way.

We well be covering the cost of each style, along with these aspects: Cost, Difficulty of installation, Durability, and my Recommendations.

Raised Bed Types:

• Corrugated Steel
• Stock Tank
• Wood Pre-Fab Kit/DIY
• Cinder Block/Stone

1. Corrugated Steel Beds

Corrugated steel beds come in a kit with everything you need, including the tools. There are a wide assortment of shapes and sizes to fit your needs and most are easy to assemble. I would strongly suggest bringing your own tools though since the pro bono ones provided are always cheap and take longer to complete the assembly than quality tools.

Cost

Corrugated steel beds can be had for as little as $30 at the time of this writing. Beds that cheap are pretty small, only offering about 8 cubic feet of space for your plants. While this may be suitable for some with space limitations, it’s not the best for those of us looking to start an off-grid garden. Stepping up to a larger size can net you anywhere from $60-$150 per unit. If you’re setting up a garden large enough to feed a family of four, that kind of investment can add up, but if you’re just expanding a little here and there, it’s not too bad.

Difficulty of Installation

Probably the easiest of all the styles to install, raised beds typically come with tools provided for complete assembly. However, those tools are produced en masse and are cheap, thus, substandard. Regardless of the tool set used, assembly of corrugated steel beds is straightforward and the provided instructions, while not perfect, are usually enough to get you where you need to go.

Durability

This is a situation where you get what you pay for. The cheaper beds can hold up given that care is taken to avoid damaging the flimsy panels. If you’re using long-handled tools to work the soil inside the beds for subsequent planting years, take extra care because it can be easy to make a wrong move. However, the more robust models, typically costing more, will take a fair amount of abuse before giving up the ghost. If taken care of they can last a lifetime.

Your biggest issue with any steel bed is likely going to be rust, and given enough time, rust will eat through the thicker panels too. I would definitely have a plan for rust mitigation when you purchase. It won’t happen right away, but by the end of the first season of use you could start seeing rust spots. The earlier these nucleus points are addressed, the better. If you’re concerned about aesthetics, then you’ll need to grab some paint that matches the finish of the beds, otherwise, any old rattle-can paint will do. When you see a rust spot forming, hit it wire a wire brush (or wire wheel) until all the rust is gone, then touch up the area with paint.

Recommendations

2. Stock Tanks

This is a popular idea that works well. If you’re looking for a quick installation, one-stop solution this is likely your best option.

Cost

For the same volume as a corrugated steel bed, you’ll pay more for a feeding trough. This is because feeding troughs, or rather, watering troughs are designed to be water tight. They utilize thicker steel designed to hold back water pressure, hence, an increased cost. But that cost does save you time during setup. This option is going to be the most expensive in terms of upfront cost, but will be the least in terms of installation time.

Difficulty of Installation

This is the easiest option to install. Just place is where you want it and fill with your choice of soil. The only other aspect you need to concern yourself with is making sure the spot you’ve chose is flat. While feeding troughs are tough, they aren’t impervious, this is why I usually suggest that no matter how flat the spot is you’ve chosen and prepped for installation, it’s better to spread out a thin layer of sand on the area. This will settle into a perfectly supported flat base for the trough to sit on once you starting adding weight in the form of soil.

Depending on what you plan on growing in the bed it may be necessary to add drainage holes in the bottom of the trough. Holes can be as large or small as you want and should be tailored to fit the use you’ve designated for the bed. I would suggest placing a layer of sand on the bottom of the trough to keep the holes free of debris and allow drainage to occur. Gravel can be substituted for the sand, you should select holes sizes and aggregate sizes to create a bed that can drain well.

Durability

This type of bed is the most durable on our list. Watering troughs are made to stand up to livestock abuse, it’s likely you won’t do any damage short of running it over with a vehicle.

Recommendations

Of the many shapes that are available, one doesn’t lend itself very well as a raised garden bed; circular. While you’ll see the same benefits regardless of the size and shape you choose, having a large circular bed introduces ergonomic problems. Primarily, if the circle is large enough you won’t be able to reach plants in the middle without significant strain, thus mitigating some of the benefits of a raised bed in the first place. There are smaller circular options which are only about 2 feet across, that would be fine, and work great for plants like cucumbers, squash, and zucchini which grow in a circular pattern. Just be careful not to go too big with circles because your back will end up regretting it down the road.

3. Wood Pre-Fab Kit/DIY

So you have a few options when it comes to wood. You can go with a kit, which will be very similar to the corrugated steel beds discussed earlier, or you can go the DIY route and build your own. Within the DIY realm you also have a couple of options focused around material selection; primarily, using a naturally rot resistance wood like cedar, or selecting a pressure treated species designed to be in contact with the ground. We’ll discuss the pros and cons of each option in this section.

Cost

Per cubic foot the cost here can be very affordable. With a pre-fab kit you’re looking at roughly the same cost-to-volume ratio as the corrugate steel options. In the DIY space you can easily rack up a larger bill, or shave some dollars by going with a less expensive material. Unfortunately I can’t offer any more acute comparisons beyond that. Most will opt to use a pressure treated 2-by option for the material. A 12’ x 4’ x 1’ corrugated steel bed goes for about $60 on Amazon. Replicating that size using AC2 treated 2” x 12” boards will run you about $85. About a 40% increase in price. If you opt for some 1-by boards you’ll be on the cheaper side of the steel counterparts. The trade-off here is durability. If you do opt for the DIY method, note that pressure treated lumber will be cheaper than a naturally rot resistant wood like cedar.

Difficulty of Installation

If you’ve ever had any experience in construction, installing a wooden raised bed is imminently doable. The pre-fab wooden bed kits are about the same skill level as the corrugated steel kits. DIY beds require more from you, but they’re very attainable. The biggest element of DIY beds is you get to decide what everything looks like. It makes a great option if you have odd shapes and spaces you want to fit a bed into.

You’ll need a larger array of tools for DIY beds. At a minimum you’ll need a drill driver, with associated bit for the screws you’ll use, a level, possibly clamps, a shovel and other dirt moving tools, a cross-cut saw, and some layout tools including a square. Most of us DIYers have those tools on hand due to a long history of accumulation, but if you’re new to the DIY space I have a recommended tools list for building planter boxes in the conclusion section below.

You also have the option of lining either a pre-fab kit or a DIY box with plastic. There’s lots of options when it comes to plastic liners, and there’s really not one that’s better than the others. Easiest is probably a thicker painter’s plastic drop cloth. You can get quit a bit of material for pennies on the dollar. Just measure it out and staple it to the inside on the walls, and floor if applicable, for a better way to protect the wood, increasingly longevity.

Durability

Wood is a durable substance that will stand up well to the work that will need to be done from year to year in the raised bed. Random dents and dings won’t be noticeable and will add to the character of the bed. Wood can be painted and that opens up lots of possibilities for aesthetics. While not as durable as the feeding trough style, wood will hold up for many years.

The real downside with wood is that no matter how well it’s been treated, or how naturally rot resistant it is, eventually is will break down and need to be replaced. This process can be slowed by treating the wood with stains and protectants, including painting, but you’ll need to do your own research to determine whether or not those chemicals will leech into the soil. The last thing you want is to get done building your beds then realize that the paint you used may be absorbed by the tomatoes you’re planting next spring. Which brings me to an important point. If you are going to use treated lumber, make sure it is safe for use as a planter box. Research the chemicals used to treat the boards. Back in the day copper sulfate was a primary means of pressure treating which would lead to excess levels of sulfates in the soils and can cause health problems down the line. Today’s chemicals are much safer but some of the older stuff still gets used, so double check before buying. Also, never use railroad ties to make garden beds. Railroad ties are cured with creosote and other chemicals that make them great for keeping trains on track, but will leech chemicals into the soil that you don’t want in your food.

In general you can expect to get 5 years out of most wood options; longer if you take protective measures. I would advise against using regular, untreated lumber as it will only last you about 2 years at most out in the elements.

Recommendations

DIY MATERIALS

Since there are no DIY kits per se, I will simply link to the major parts you’ll need to build a raised bed to your own specifications.

Tool List

• Drill Driver
• Bits
• Level
• Shovel
• Landscape Rake
• Hoe
• Cross-cut Saw
• Speed Square
• Pencil

4. Cinder Block/Stone

Technically you’re probably not going to use ‘real’ cinder block for garden beds. It’s likely the Lowe’s down the street doesn’t even sell the stuff. Real cinder block was made from left over ashes and binders and has been phased out of the last 50 years. What we commonly refer to as cinder block today is actually a concrete block. I make the distinction to point out that real cinder block should not be used to build garden beds for the same reason that you shouldn’t use railroad ties. Chemicals will leech into the soil causing problems. However, concrete blocks are perfectly fine and work great as a raised bed material.

Cost

Concrete blocks are pretty inexpensive on their own, but can add up quickly if you’re making complex shapes for your beds. This concept is true regardless of you’re DIY material of choice. Making a container in the shape of a circle will always yield the greatest internal volume to perimeter length ratio. Any other shape will reduce that ratio, and more complex shapes like horse shoes will really add up the cost.

Either way, using our previous comparison, a single-tier raised bed that is 12’ x 4’, made of concrete blocks will only run you about $50, using approximately 26 blocks. This isn’t a true apples-to-apples comparison as a concrete block is about 8” tall with no reasonable way to get a 12” height out of complete blocks. Adding a second tier will put you around 15-16” tall and double the price. You can make the bed as big or small as you like with a price to match. What’s really nice for this option is that the savvy DIYer might be able to find a few blocks here and there on places like craigslist and FB marketplace for cheaper or even free. I was able to score about 250 blocks from a guy cleaning out his parents backyard after a fire had destroyed some of the house. Everyone was evacuated safely, but the fire prompted a change and he decided the junk in the back yard needed to go. The blocks I got were not standard 8 x 8 x 16 block though. They were custom molded from a while back and came in various sizes. So keep an eye out and take a tape measure to ensure you’re getting standard sized blocks if you go this route. It’ll save some headache during the build.

Difficulty of Installation

This type of an installation requires the same skill level as wood planter boxes, but in different areas. You won’t need to do any cutting or joining, but you’ll still need some layout skills.

Unless you need a funny shape, you won’t need to cut the blocks. I advise you to avoid this unless it is absolutely necessary. It slows you down and creates an odd shape that you’ll need to replicate in the future if you want to add beds that are the same size for aesthetic purposes.

The build process is pretty simple, but it involves more physical labor. First you need to layout the area the bed will be, then level it so the blocks will all line up perfectly. That will take some time. Since you’re going to be eradicating any weeds or grasses from the area I suggest tilling the spot thoroughly to loosen the soil, making it easier to level when installing each block. Next you’ll have to layout a level line along one side, then start laying blocks. Use sand under each block to make it perfectly supported and level. Keep going down each side until you’ve made your way around the perimeter. Once your done, add something into the holes to really anchor them in place. This can be anything from concrete to soil, even pea gravel. I like to add soil and plant things like marigolds and other herbs in the holes. This gives me more planting space and marigolds repel insects that eat your garden.

No need for mortar since there won’t be enough soil pressure to move the blocks once they settle. If you’re concerned about the blocks moving due to soil pressure or rain, etc., then you can grab some rebar and pound it down into the ground through the holes of the blocks. This will give the block something to grab if it does start to go.

Durability

Concrete blocks are very durable and will last a lifetime if installed properly. A hard strike from a hammer or other implement will damage them. But given that the blocks aren’t mortared in place, replacing one is a simple as removing it and putting a new one down.

DIY Materials

More Thoughts

There are many ways to skin a cat, and building a raised garden bed is no different. I’ve covered some of the more popular options, but you can do it however you like. I like using materials that will last, so I usually opt for stone or steel. I don’t like doing the same project twice, but for some instances, the cheaper option may be better. I do want to mention that there are other materials that can be used, like old tractor tires, bathtubs, etc. If you want to, just pick something that’ll hold dirt and you’re good to go. The following paragraphs are meant to be a guide on some things to consider that are universal to all the different styles of raised bed.

Weed Mitigation

Probably the most important aspect of using a raised garden bed is to control weeds, at least it is in my neck of the woods. We’ve got Bermuda grass around here, and it spreads via both rhizomes and stolons. It is a formidable foe. I’ve even seen it growing from stolon cuttings inside the watering trough for our cows. No idea how they got there, but they stayed for a few weeks before I pulled them out.

While you may not be dealing with such invasive enemies, weeding is something we all hate, and frankly don’t have the time for. So when looking at raised bed designs there are a couple of aspects that will directly affect the amount of weeding you have to do.

First is the bottom of the raised bed. With some like the water trough idea, the bottom of the planter is completely protected, hence, those underground spreaders are stopped dead in their tracks, so you’ll only be worried about our second issue, wall height. With beds that have open bottoms, species like Bermuda grass will easily push up through anything less than 2 feet of soil and mulch, making your life that much harder. That being said, 2 feet of soil and mulch will deter weeds from growing, but it’s not a 100% deterrent.

The height of the walls will directly affect the amount of weed intrusion, the higher the better. Higher walls means less seed blowing in from the favorable winds. Combined with a thick layer of mulch and you’ve got a potent weed control method.

All forms of raised bed will provide some weed control. Understanding why will help you decide what’s most important to you.

Ergonomics

Along with the benefits of weed control, higher walls (a taller raised bed) will make all operations performed in the garden easier. There is one exception to this; initially filling the bed with soil, but everything else is much easier. Having a taller bed prevents bending over and saves your back, especially if you’re working for long hours.

The downside to taller beds is finding soil to fill them up with. Soil is expensive, so striking a balance can be an important task. One way to solve both issue is to buy/build a raised bed that’s shallow (maybe 12” deep) on legs that brings it up to table height, like this model. This is a great solution for a minimal added cost. You’ll need a bottom to the bed since its raised, but that’s a decent trade off. However, if you’re planning on planting a crop which has deep roots, this will present a problem. When a bed is bottomless on the ground, roots can grow as deep as they want. In a bottomed bed you restrict the places the roots can go.