raised beds with galvanized steel?

In your application, I am not sure how long you would galvanized last but I wouldn't imagine it would be much shorter than galvanized beds out in the yard?

I believe the conservative estimate expected life is advertised to be around the twenty year mark for normal applications. I have seen 30 years also mentioned so take that as you will. PH, Chlorides, Moisture can all reduce this so it is hard to give the best estimate. I think the only thing that would leach from galvanized would be zinc?

Maybe someone here has better more in-depth knowledge to assist

We use raised galvanized steel beds in our community greenhouse. Some are lined either for experiments using hugelbeds or self watering beds.

Regarding toxicity: this is an issue I care about, since I garden in stock tanks, and raised planters I made with roofing metal (though those were made with 8’ x 4’ green and white sheets, so that’s probably a different question).

1.  Zinc vapor is toxic. It is produced when zinc is heated. Welders, be careful. However, hot summer weather is not hot enough to produce this effect.
2. Zinc should not be used to process or store acidic foods. So don’t pickle your veg in your stock tank or galvanized bucket.
3. I also read that zinc is toxic to fish. We always had mosquito fish in our galvanized takes used to water our horses and cows, and they and their progeny lived for years. So I guess there wasn’t a lot of leaching going on. And trust me - those tanks were old.


We do need some zinc in our diet. Normal growing practices shouldn’t leach zinc, or at least enough to exceed our thresholds.

Maybe avoid growing plants that require acid soil.

A couple of links:

https://www.oregonlive.com/hg/2020/01/are-galvanized-troughs-safe-to-use-for-veggie-gardens-ask-an-expert.html

https://onehappylemon.com/is-galvanized-steel-toxic/

https://accessiblegardens.org/the-pros-and-cons-of-using-galvanized-steel-in-your-garden/

https://ask2.extension.org/kb/faq.php?id=324102

All of the industry related sites also say it’s ok.
But ideally I would like to see this topic discussed in the scientific literature but did not succeed in finding any. If there are any chemists or material engineers, etc, out there, I would appreciate your thoughts.

I'd be more concerned about lead (and possibly other heavy metals) than the zinc itself. Some hot galvanising processes use a small amount of lead on purpose to help the zinc flow and stick to the steel. And even when that is not the case, sometimes the zinc itself is not very highly refined and there are other substances that got mined along with it, which can include lead, mercury, cadmium, arsenic and other nasties. If you're worried about it, get a test done or find a different material.

DON'T DO IT!!!
Gnar shred. Never considered the toxicity of the metal. I spent a lot of time building beds from used roofing metal in one of my greenhouses. Even with the white side out, the metal gets hot, the soil dries out on the edges, becomes hydrophobic, yields suffer. I will be slowly rebuild them as time allows. The walls of the new beds will be made from two separate sections of 1/4" hardware cloth backed with cattle panel. In between the two sections will be a 4" space to be filled with wood chips. Say hello moisture retention, temperature regulation, air pruning and mycelia explosion!
Yes a little metal,  but I've got a sneaking suspicion something else will pick me off first.

My experience has been positive. The self watering beds have been able to go over 40 days without watering. A pepper bed 7x3 with ollas was prolific and usage of water was, an incredible 35 gallons for the season. Does the underbed reservoir mitigate overheating ? Possibly. The hugel beds don't seem to be overheating. Our trials are still in their infancy but so far we have been pleased.

Robert Ray wrote:My experience has been positive. The self watering beds have been able to go over 40 days without watering. A pepper bed 7x3 with ollas was prolific and usage of water was, an incredible 35 gallons for the season. Does the underbed reservoir mitigate overheating ? Possibly. The hugel beds don't seem to be overheating. Our trials are still in their infancy but so far we have been pleased.

Very good point.

I always fill most of the space in my tanks with wood and big yard trimmings, then about 12” of organic soil for containers. In winter I bury my kitchen waste directly into the soil, just deep enough to so that critters (including my little terrier who can jump high), don’t dig it up, and plant a cover crop. We get frost here occasionally but no ground freeze.

I just moved, and had to empty my tanks to move them (big mess, hard work, worth it). As a result I got to see the that wood that had been in them for two years was chock full of mycelium.  And worms! Many worms. I was pleasantly surprised. Maybe because of the winter kitchen waste? (Yes, I moved the wood too!).

I also found that I needed to water far less than I expected. Even less than wood raised beds sitting directly on the soil. My soil does not overheat, and believe me, summers here are very hot now.  And the plants thrive. I grow peppers, beets, tomatoes, tomatillos, cucumbers, peas, beans, squash, and greens. As well as volunteer potatoes and sweet potatoes that sprout from the kitchen waste I bury when I don’t eat my supply fast enough.

I credit the 1-1.5’ of wood in the bottom for these benefits. And I don’t have to haul so much soil with all that wood taking up space. Win win.

Now that I have seen the wood after 2 years, I’m estimating that maybe every 4 years or so I should peel off the soil and add more. The “old” wood will still be doing its job, but by then of course filling less space. Adding new wood about then should give it the year or two it needs to come up to speed while the old wood continues to provide benefits, and also free me from having to top off the soil as much due to the old wood settling.

I just got a Medicare card in the mail and I have a few health challenges.

I have no idea whether stock tanks are cost effective for people growing things as a business.

But they have allowed me to be able to continue to feed myself and to do it as close to a “permaculture way” as I can. And in addition to food, I get the fun of experimenting.

It would have been a lot cheaper to use the “rubber” tanks (ick) or to build wood or concrete tanks.

But, I can move my tanks around. And they are high enough to work in without getting up and down from the ground. There are fewer weeds, and they are easier to manage by hand (I do mulch the plants, chop and drop, etc). They have a built in drainage hole just the right size.

I’m a fan. Can you tell?

Ralph Anders wrote:DON'T DO IT!!!
I spent a lot of time building beds from used roofing metal in one of my greenhouses. Even with the white side out, the metal gets hot, the soil dries out on the edges, becomes hydrophobic, yields suffer. I will be slowly rebuild them as time allows.

I had the same experience with my roofing beds (I am sad that I had to leave them behind 2 years ago,  especially because they are a foot taller than stock tanks, and cheaper, too).

This is what I used to do when the soil pulled away from the sides: shove wood in the spaces. Mostly I got it from my little orchard (I miss that too). Green, dry, it didn’t matter.

I did it when the soil was an inch or so from the sides. It served to insulate the soil (and in the long run helped with soil building).
When the wood was there, the soil stayed put.
At first I  did it twice a year (spring and midsummer). After a couple of years, mostly just once.

Of course different climates likely have different results. Where I live it rains all winter, sometimes night temperatures dip below freezing (often enough for one to make sure outdoor spigots are insulated). And of course the occasional ice storm that brings us to our knees.  Summers are dry and increasingly hot (like in the mid to high 90s hot).

I built several raised beds with used corrugated steel panels and reclaimed redwood fencing. I like them a lot, and have had no issues with veggie yield. I'm not sure, but I believe they are about 3 years old. One of them ever took a hit from a shed we took down, and only had minor damage, easily fixed.

Jen Fulkerson wrote:I built several raised beds with used corrugated steel panels and reclaimed redwood fencing. I like them a lot, and have had no issues with veggie yield. I'm not sure, but I believe they are about 3 years old. One of them ever took a hit from a shed we took down, and only had minor damage, easily fixed.

Nice looking planters!
I have some stuff left over after the recent move. I am inspired to build some like yours.
In fall when the crazy heat goes away.

Thanks
I'm not a carpenter by any standards, and these were some of my first beds. Built using a circular saw and drill.  There's a lot of mistakes, and flaws.yet still they have held together, and function well.
I really like them. My only issue has been where the wood meets the steel leaves a small gap, where Bermuda grass sneaks in.  If I were to do it again I would try to block that gap.  Otherwise they are great.
These days I'm just Building wood beds made from pallets to save the steel for other purposes.
I'd love to see what you built when it's cooler.
Happy growing, and building

Jen Fulkerson wrote:Thanks
I'm not a carpenter by any standards, and these were some of my first beds. Built using a circular saw and drill.  There's a lot of mistakes, and flaws.yet still they have held together, and function well.
I really like them. My only issue has been where the wood meets the steel leaves a small gap, where Bermuda grass sneaks in.  If I were to do it again I would try to block that gap.  Otherwise they are great.
These days I'm just Building wood beds made from pallets to save the steel for other purposes.
I'd love to see what you built when it's cooler.
Happy growing, and building

Oh, I remember Bermuda grass! (I lived in Bakersfield for many years). I will be sure to watch out for gaps. Instead of Bermuda grass, here we have Himalayan blackberry.

I don’t have corrugated steel, but I do have the flat-ish roofing steel. When I come across “scraps,” I like to put them under my stock tanks so it's easier to just mow around them instead of weeding.  But somehow after organizing my tanks here at my new house, I have leftovers .

I  would like to have some tall planters again that are open to the ground, like I did 2 houses ago.
I think your design will be perfect for using those leftovers, and not having to shop for supplies.
Except the circle saw. I have my trusty sawsall, but gave away my circle saw (I got tired of packing and carrying things that I wasn’t using often).  I bet another one will show up by fall.