How To Build a Metal Raised Garden Bed

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Growing food in metal raised garden bed is a crucial step in one of my house goals. I love the zen of combining beauty and function. I was able to turn a pretty ugly portion of the yard into a thing of beauty.

After days of deliberation over logistics, size, aesthetics, and cost between the different types of raised garden beds, I eventually settled on corrugated metal raised garden beds. I read several other accounts across the web and planned out my own version, a combination of the best parts, plus some fresh, original ideas. This is the result.

DIY Raised Metal Garden Bed finished
DIY Raised Metal Garden Bed Finished at Last

Thoughts and Process

Some questions I’ve been asked and have asked myself.

Will the corrugated metal rust?

Nope – it is galvanized and will last a long time. However, the galvanization is a coating on the metal. I’ve broken that layer when cutting some of the pieces and drilling holes with the screws. I’m not sure how fast rust will spread, but I am now on my way to finding out!

How hot does the metal raised garden bed get?

So far, I’ve felt the metal in 90+ degree weather. It remains fairly cool to the touch. Partially the galvanization and partially insulation from the soil on the other side. It still has a wicked glare, though.

How does this affect frozen soil?

While I don’t live in a growing zone nor climate where the soil has freezes, I was told a raised beds means warmer soil sooner, increasing the potential growing season.

Are the sheet panel edges sharp?

The precut edges aren’t sharp at all. They haven’t cut me yet and I’ve gotten pretty wild with handling them. The edges I cut with the reciprocating saw are wicked sharp. That was part of the reason for using wood corners on the outside instead of inside.

Why is the raised bed so high?

Mostly aesthetic, partially so I don’t have to bend over as far when picking shorter plants like chilies. Having a higher bed also provides a bit of disease resistance.

Where can corrugated metal sheets be purchased?

These are in the roofing section of your local home improvement or hardware store. They generally come in 8 foot, 10 foot, and 12 foot sections. I based my size on what would create the least amount of waste or leftover materials.

Are galvanized steel garden beds safe?

Absolutely! There is nothing in part of the galvanization process and steel process which will leech and harm you through the foods you grow. Zinc (from the galvanization process) poisoning comes from inhaling the metal, not ingesting it. You will hear about galvanized steel not being safe when you are cooking with it. Soil and metal garden beds are completely fine.

Planning the Metal Raised Garden Bed Layout

This whole project started when I had 3 large trees die and come down in the yard freeing up tons of potential sunlight space. I wanted to slowly tackle the yard in stages, and home-grown food was a priority. With a kind of L shaped open area between grass, bulbs, and the fence, I had a large stump to work with.

To help guild the layout and maximize potential sunlight, I put down several bricks at different parts of the day, marking shady areas. After several days of adjusting bricks to ensure the beds were in the sunlight for the most amount of time, I had a basic area to work with.

Grading dirt for metal raised garden beds
Grading dirt for metal raised garden beds

I took the time in between evaluating shade to level and grade this entire area. I also pulled up a lot of very large roots from the tree in the process. As for the weeds? One of my favorite tools is a sharp hula hoe. In addition to destroying the root systems of weeds, it tills the soil.

Clearing weeds with hula hoe and prepping
Clearing weeds with hula hoe and prepping

The shade ended up being in the perfect spot for me. I had enough of a buffer between the planned beds and fence to walk and tend to plants, which happened to be where most of the shade fell.

Planning raised bed layout with old bricks and scrap wood
Planning raised bed layout with old bricks and scrap wood

I lucked out with my bulbs as well. I knew the metal raised garden beds would be 8 feet long, based on metal sheet and lumber sizing in order not to have waste. The bulbs were 11-15 feet from the fence, providing enough room on each side for beds.

Leaving 4 feet width for each bed and 3 feet between them for walking, I found I would be able to fit 3 raised beds between the large stump and the shaded areas. That is 96 square feet of growing area. 96 more than I had before!

With bricks placed on each bed corner, distances between metal raised garden beds measured for comfortable walking, and making sure things were aligned in a way which looked good from multiple angles, I began trenching for irrigation.

Digging trenches for irrigation pvc pipes beneath the raised beds
Digging trenches for irrigation pvc pipes beneath the raised beds

You know those roots I mentioned. Yeah. This happened several times. It also screwed up my wonderfully leveled area. I laid down piping like this to make sure I was digging mostly straight. Let’s just say I use the term “straight trenches” very loosely. I’m also making sure to post my mistakes to properly dissuade any friends (Robert) reading this from asking for help. After filling in the trench, I have to admit I got pretty lazy on re-leveling the area. I found out just how bad I not-leveled later on.

With a lot of measurements taken, trenches dug, and an idea of how many raised beds I could fit in the area, it was time to go shopping. As an experienced DIY’er, I know that any project has a 3-trip minimum to the hardware store. I always overbuy small parts. Its terrible to have to make the drive back to the store for one measly 29 cent part.

Plans for Raised Metal Garden Bed Materials and Supplies

I wanted to use screws which would blend in with the wood, so I opted for red star headed screws.

For wood, I ended up with redwood based on availability, although cedar would have been a great option as well. I am one of those people that spends a ton of time bringing down half the pallet of lumber evaluating curves and how dry each piece is. And yes, I put it all back. I bought 16′ pieces, but you can buy 8′ as well and double the amount appropriately.

I wanted to get some kickass soil for my new raised beds, so I got a “veggie mix” which was comprised of “premium” organic topsoil, humus, mushroom compost, sand, lava fines. Each bed needed 2.25 cubic yards per bed, but I also wanted extra for some other garden areas while I was getting it delivered.

While corrugated metal was the main project, I also opted to get some pavers are build a 4th bed in order to deal with a strangely shaped area and large stump, which had me stumped for ideas. Yeah, I just went there.

In addition to building the metal raised garden beds themselves, I wanted to redo my irrigation and reroute some of the underground piping to each bed. I always buy new cement and primer for large projects, as I usually go a ways between irrigation fixes and the pvc cement expires quickly.

The adapters and connectors purchased were on a case-by-case basis. I already had some parts, and had to get more than necessary in other areas. You shouldn’t follow my irrigation purchases exactly.

Irrigation Protip: If the cement is jelly or gel like in the least bit, it has gone bad. The cement should be very runny.

Laying out the supplies for the metal raised garden beds
Laying out the supplies for the metal raised garden beds

List of materials for 3 metal raised garden beds:

  • Raised bed: 8′ corrugated metal galvanized – 9 pieces – $157.32
  • Raised bed: 1 pound pack 3″ red star/pax screws$8.47
  • Raised bed: #8×3/4″ self drilling pan sheet metal screws$7.25
  • Raised bed: 2×4-16′ redwood – 3 pieces – $57.81
  • Raised bed: Soil compost mix – 6.75 yards – $350
  • Raised bed: Tan pavers – 60 pieces – $31.18
  • Irrigation: Purple primer$6.41
  • Irrigation: PVC cement$5.40
  • Irrigation: 3/4″ Thinwall 10′  – 3 pieces – $5.70
  • Irrigation: 1/2×3/4 pvc male adapters  – 3 pieces – $3.42
  • Irrigation: 3/4 pvc el45 slips – 2 pieces – $2.28
  • Irrigation: 3/4 pvc 90 degree elbow – 3 pieces – $1.41
  • Irrigation: 3/4×1/2 pvc bushing – 2 pieces – $1.92
  • Irrigation: 3/4″ pvc coupling  – 2 pieces – $0.95
  • Irrigation: Manifold with adjustable flow 4 outlets – 3 pieces – $17.34
  • Total cost: $681.51. Without the soil, that is $110.40 per bed.

Tools and Equipment Used

Estimated Time

  • Planning, thinking, measuring, prepping land: 5 days
  • Irrigation setup: 3 hours
  • 3 raised beds materials purchase and assembly: 1/2 day
  • Moving dirt: 1 day
  • Planting: 1 hour

Irrigation

The plan was to run 3/4″ lines from 2 main pipes. Based on distance and roots discovered, I didn’t want to feed all three beds from the same line. I also wanted to minimize the amount of elbows I would need to fit. If I had to dig around in the future, simplifying the lines would make this easier to not break things.

I discovered another secret to plumbing irrigation. I wanted to photograph some of the process for this blog, so I managed to convince my dad to do a lot of the work for me. I told him the entire point of my blog was a long-term plot to get him to do the shitty part of the work for me. I like to think it worked.

He started by priming both ends of the pipes. When connecting multiple pieces together, try to do them all at once and quickly. You must wait 15 minutes before moving them around to allow the cement to cure. If you have to do 4 or 5 pieces on a strange turn, as pictured below, that can be a lot of wasted time.

Priming pvc irrigation for the raised beds
Priming pvc irrigation for the raised beds

You’ll also want to keep a couple clean rags nearby. A clean work area and clean pipes will ensure you have a problem-free process. After applying the purple primer, add on a nice thick gob of cement, covering all sides. Try not to inhale. Push the fittings together and hold them together tightly for about 20 seconds. This is a good time to ensure things are straightish and aligned correctly. You won’t get another chance unless you want to cut and redo things.

Waiting for the pvc irrigation pipe cement to cure and set
Waiting for the pvc irrigation pipe cement to cure and set

I somehow managed to plan the beds with the biggest root found right where I wanted to place one of the irrigation manifolds, dead center in a bed. I adjusted for off center, but it was still a bear to get into place. Correction: It was a bear for my dad. When placing vertical pipes, it is crucial to make sure they are straight. A level is recommended to assist with this.

Setting vertical pvc irrigation to come up through the middle of each raised metal garden bed
Setting vertical pvc irrigation to come up through the middle of each raised metal garden bed

If the pipes aren’t perfectly straight, the mistake shows up immediately. Short of redoing the entire thing, there isn’t much you can do about it. I got the idea about using a level on the third pipe plumbed, featured in the forefront.

Filling in the irrigation trench and ready to move the metal raised garden beds in place
Filling in the irrigation trench and ready to move the metal raised garden beds in place

The curing process for the irrigation takes a couple hours, which meant it was time for building the actual raised beds while the PVC cement did its thing.

DIY Corrugated Metal Raised Garden Beds

Positioning each raised metal garden bed over its spot and eyeballing the layout
Positioning each raised metal garden bed over its spot and eyeballing the layout

Cutting the corrugated metal panels

With x9 8 foot panels, 3 needed to be cut into 4 foot pieces for the ends. The sheets were laid out on some scrap lumber to keep them above the ground and the reciprocating saw was put to work. 4′ / half was measured out and marked with a sharpie to stay on task with the reciprocating saw.

Preparing to cut each corrugated metal panel
Preparing to cut each corrugated metal panel

In cutting the panels, I ended up being so happy to have an extra set of hands helping. The extra pair helped in stabilizing the metal and keeping it from shaking too much from all the saw action.

Cutting the corrugated metal sheets with a reciprocating saw
Cutting the corrugated metal sheets with a reciprocating saw

As you can see below, the cut edges are pretty sharp. The redwood 2×4 corners would serve to help mask imperfections and prevent accidental injuries.

Cut corrugated metal panels ready to be screwed back together into garden bed form
Cut corrugated metal panels ready to be screwed back together into garden bed form

Redwood Corners

The redwood 2×4’s were all cut down into 2 foot pieces. But therein lies a problem. You’ll notice when you buy lumber, 2x4s are all slightly smaller. An 8 foot piece will yield 3 four foot pieces and a fourth slightly smaller piece, plus you have to account for the width of your saw blade removing wood. The found solution was to make sure whichever piece was short was used on the backside of the assembled bed.

Putting the raised metal garden bed together
Putting the raised metal garden bed together

In addition, when screwing 2 of the pieces together to make a single corner, pay attention to which side of the wood is showing. Consistency will keep everything looking amazing.

Make sure to pre-drill all of your holes to prevent the wood from splitting. This is a critical step and you will find yourself incredibly frustrated if you need to replace a single 2 foot piece. This didn’t happen to me on THIS project, but I’ve had it happen plenty of other times. This is when you will be so happy to have 2 drills going. One for drilling and one for screwing.

I did 3 holes and screws per corner.

Predrilling the redwood to reduce the chance of splitting the wood
Predrilling the redwood to reduce the chance of splitting the wood

You might be wondering why I told you to get the pax/star/torx screws. For one, they resist cam-out much better than Philips and slot head screws. Less stripping for your screwing. Uh huh. It also allows a higher torque to be used. You can reach your desired torque consistently and better drive the screw’s head into the wood without the bit slipping out when maximum torque has been reached.

Installing the screws halfway into the redwood in preparation of attaching the corrugated metal panels
Installing the screws halfway into the redwood in preparation of attaching the corrugated metal panels

Corrugated Raised Bed Assembly

With your redwood corners screwed together, law them out and set the sheets on top. Start with the 8 foot longest sides. Again, make sure you are consistent and careful with how your corners are placed. Don’t forget about the one short piece to accommodate.

You will notice the sheet extends past the length of the wood. You have 3 options for this. The least recommended is to cut the extra. What I ended up doing was making the extra the bottom portion and bending it inwards. What I would have rather done is evened it out and bent both top and bottom. The bottom holds dirt and helps to keep the sides stable with the weight of dirt and water once the beds are filled. Bending the top as well would allow me to install a wood railing, adding some extra stability. I might still do something, depending on how the growing season goes.

Grab a handful of sheet metal screws and start attaching. I did 4-5 screws, attached to the inside, depending on how the sheets were bending.

Screwing the corrugated metal panels into place
Screwing the corrugated metal panels into place

This is where having a second person helps. The person not screwing can provide counter pressure to make sure the corrugated metal is tight against the wood. Standing in the sun so shade is on the person screwing helps a lot, too.

When attaching the short metal pieces to the wood, I found placing the corners on wood to keep them slightly off the ground helped a lot. A second person holding and providing counter-pressure is key in this step. I crouched on the inside of the beds and tediously attached all sides.

All four sides of the raised metal garden bed screwed together, upside down
All four sides of the raised metal garden bed screwed together, upside down

With all four sides attached, the extra metal on the bottom, facing up, was bent inwards, then attached with a sheet metal screw for good measure.

Even with self-drilling sheet metal screws, I had a lot of slippage. I’m pretty sure I had a green thumb of sorts. Or at least a blood blister between slipping and holding the spinning screws waiting for it to catch.

Green thumb or blood blister from the metal screws: gloves advised
Green thumb or blood blister from the metal screws: gloves advised

The first bed was done and it felt pretty successful. The other 2 were knocked out very fast in comparison to the first. It also helped I didn’t stop every moment to take photos.

With all beds assembled, they were easy to lift and put into place.

Perfecting the spacing plans for two metal raised garden beds
Perfecting the spacing plans for two metal raised garden beds

With the beds mostly in place, I grabbed a tape measure and perfected the placement with spacing.

Okay, remember earlier how I mentioned after running irrigation, I was lazy on regrading the dirt? Yeah, this is what happened. Now, I was forced to level. So much for getting away from that.

Aiming for between the bubbles on the short side, a couple shovel-fulls of dirt later, a lot of harrumphs, the beds were ready for the next stage. Dirt.

Leveling and regrading some of the dirt and slope for the metal raised garden beds
Leveling and regrading some of the dirt and slope for the metal raised garden beds

Dirt Delivery

A local company delivered right into my driveway.

10 cubic yards of premium soil compost mix
10 cubic yards of premium soil compost mix

This is what 10 cubic yards of dirt looks like. I was quite pleased with unintentional sign placement alongside the dirt humps. If you recall from earlier, I needed 2.25 cubic yards per raised bed, and ordered additional for the rest of the yard.

10 cubic yards of lovely dirt humps on my driveway
10 cubic yards of lovely dirt humps on my driveway

The downside with creating beds which are 2 feet tall, is filling them with dirt required shoveling from the wheelbarrow to the bed. I could simply dump the wheelbarrow. I contemplated building a ramp, but due to space, I opted for a workout.

When filling the beds, in between each wheelbarrow’s worth of dirt, I sprayed it down with water. This would help with settling and keep the dirt from really going down once I had plants going on. I was incredibly pleased with how everything looked once the beds were full.

Filling the metal raised garden beds up with dirt
Filling the metal raised garden beds up with dirt

In researching this project, a lot of other blogs mentioned support systems and bulging for the sides. I opted for no such thing. Evaluating the sides and their bulge, I felt it was pretty minimal. Everything felt quite sturdy. I liked the seamless aesthetics over extra wood.

“Hey dad, can you fill this bed for me while I take some photos?” Is a line which worked well for one out of three raised beds.

Filling the metal raised garden beds up with even more dirt and some shovel action
Filling the metal raised garden beds up with even more dirt and some shovel action

Those bent insides worked really well in holding the sides together and stable. Dirt rested on the lip and kept the metal from sliding outwards.

Peering inside the raised metal garden bed and evaluating workmanship
Peering inside the raised metal garden bed and evaluating workmanship

With everything filled, in place, and irrigation tops attached, I felt incredibly happy with how the beds turned out. They were beautiful. I couldn’t wait to start planting.

Attaching irrigation valves for each raised metal garden bed
Attaching irrigation valves for each raised metal garden bed
Surveying how crooked my pvc irrigation techniques are. Oops.
Surveying how crooked my pvc irrigation techniques are. Oops.
This raised metal garden bed is a hot spot for chilies and soon to be hot sauce!
This raised metal garden bed is a hot spot for chilies and soon to be hot sauce!

Bonus Round – Pavers Raised Bed

You might be wondering why the third bed is not aligned like the other two. Well, I happen to be the proud owner of a very large stump. I ran back to the store and picked up some pavers. I wanted to dry-lay a multi-tiered bed for larger plants to grow up into the stump and hide it. Doing tiers would also allow me to avoid mortaring.

Building a raised bed with paver stones
Building a raised bed with paver stones

I had to play with a multitude of layouts and designs to figure out what worked and also allowed ample room between raised beds. This is what I ended up with for the bottom tier.

Paver stone raised bed with two layers and utilizing a rotten tree stump
Paver stone raised bed with two layers and utilizing a rotten tree stump

For the second tier, I simple placed the pavers on top of the dirt where they stand with their own free will. As much free will as pavers have, at least.

The Final DIY Corrugated Metal Raised Beds

Finally! Please excuse my wild arugula and trampled bulbs. I am thoroughly thrilled with how the beds turned out. As an unexpected bonus, I have a couple hummingbirds that come down and bathe when the irrigation is on.

The DIY Raised Metal Garden Bed Project is complete
The DIY Raised Metal Garden Bed Project is complete
Checking out the beauty of the metal raised garden beds from the roof
Checking out the beauty of the metal raised garden beds from the roof

One Year Later

One year into using these beds – I am thrilled with them. Water retention is great. The metal never got too hot in the summer. The wood and shape stayed intact once the dirt settled as shown in the photos above during installation. This project was totally worth doing.

Metal Raised Garden Bed Corrugated Metal Pinterest

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21 thoughts on “How To Build a Metal Raised Garden Bed”

  1. Warren B. Cederholm, Jr.

    I’ve been trying to decide between cedar and galvanized metal. Your tutorial has just convinced me to go with the metal, it looks great. I notice that you did not put a barrier down at the bottom of the bed; most other videos I’ve looked at do use a weed barrier. Is there a reason you did not?

    I’m thinking of using pvc piping or insulating foam for around pipes to cover the top edge of the metal so it is not so sharp. The foam should not only protect us from scraps and cuts, but also protect the plants if they begin to grow over the sides of the bed. I do want to come up with a means of making a removable frame for on top of the bed so I can cover it with plastic and get an earlier start on the growing season and also protect the plants from an early fall frost.
    I figure some kind of narrow pvc piping should be able to be bent over it to form a frame for a clear plastic tarp.

    I have the advantage of living next to a rather large stream which passes by my house in a cement channel. My plan is to get an electric pump that I can leave down in the channel and turn it on to irrigate the beds using soaker hoses. This should supply me with an endless supply of water whenever I need to water the plants. I’m also going to be planting a few fruit trees in a near by area so that should be a great help especially the first coup of years to get them started. Its possible with a long enough hose I can water everything in my entire yard for only the cost of the electricity. I’m also imagining solar panels in the future to even cut the electric cost.

    Now if it would just stop raining so I can get working on this project. We’ve had a really wet spring and every time we have a dry day I have to spend 3 hours mowing the lawn instead of getting my garden started.

  2. Thanks for sharing your design. How did you tap into the water supply, did you run a line out from your house or from the spigot on the outside? And how do you control it?

    1. Hi Matthew,

      I actually had existing irrigation that I tapped into. There were shrubs, bushes, and bulbs in the area before which received a lot of water, so it was easy to re-run where the pipes went and not worry about water pressure.

      The entire irrigation system is hooked into the main water line, then goes through irrigation valves and manifolds. All of that was done before me, so I’m not too privy on how it works in detail.

    1. I just got mine at Lowes. Building it today and tomorrow with some minor modifications. A few more sides and a top piece of wood around the metal.

  3. Hi, The beds you made are so attractive to the eye! Nice job!
    I want to build 3 for myself ( I need to control rabbits!). They would be 8′ long, like the ones you built. .
    I have one concern. It appears in some of the photos, that the long sides are slightly bowed out. Am I seeing this correctly? If so, any ideas to keep this bowing to a minimum? Thanks!

    Bill

    1. Hey Bill,

      Yes, the long sides bowed out a bit, and the short ones a tiny bit as well. I’d imagine installing a 2×4 on the inside of each side at an angle / from top corner to bottom corner, then drilling the corrugated metal into the wood would prevent this. You could also do the outside, but that would probably ruin the aesthetic a lot more, if you are going for a similar look. Another option would to not have the beds so deep – I’m sure having the beds as tall as they are is a big factor. Good luck with your project!

  4. It looks sharp and is a terrific use of space. I think it will probably rust where you drilled through the metal, but there is probably some type of aerosol coating you can apply

  5. Wow, those roots!!! I would have been using a few choice words while redoing the process. I love this design and all the information in this post! Saving this for when I find my next home. Just moved still haven’t found the right home!


  6. Wow! This post on how to build a corrugated metal raised bed is packed with so much valuable information. My husband and I have been discussing building raised beds in our backyard, but it was hard to visualize the process until now. Thank you so much for all of the step-by-step instructions and images. They’re super helpful!

  7. Ok – I LOVE THIS. I desperately need a solid raised bed structure to keep the idiotic rabbits out of my lettuce patch. Sigh. Thank you for this detailed post!

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