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topic 45056

Galvanized steel for planting vegetables



A discussion started in 2007 but continuing through 2018

(2007)

Q. Is galvanized steel safe to use as tomato planters? I am worried about leaching of metals into the vegetables.

Barbara Meserve
hobbyist - Fallston, Maryland


(2007)

A. Zinc is an essential dietary element.
It is extremely unlikely that any will end up in the tomato but if it does you can put the price up.

geoff smith
Geoff Smith
Hampshire,
       England



(2007)

A. Galvanized steel is commonly used for tomato plant towers. Don't process the fruit in galvanized (or bare steel) containers though, as the acidity will dissolve some metal.

Ken Vlach
- Goleta, California
contributor of the year

Finishing.com honored Ken for his countless carefully
researched responses. He passed away May 14, 2015.
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May 27, 2009

Q. I bought some large galvanized planters with no drainage holes (for indoor or outdoor use). Since they are square, I am having a hard time finding liners that allow me to maximize the space. I would like to plant some herbs and small tomato plants in them. If I drill holes in the bottom and plant directly in the steel, would the planters be considered food safe for planting?

Linda Gates
consumer - Bethesda, Maryland


June 17, 2009

Q. I use galvanized screen and fencing around my garden. It is buried in the soil, around the plants, to support vines. I also allow my vegetables to sun and dry on a galvanized screen tray. Are there any human health problems associated with vegetables or roots coming in contact with galvanized screen wire? Thanks.

Lance Laton
- Atlanta, Georgia


June 18, 2009

A. Hi, Linda. The earth is largely iron, and zinc is an essential nutrient. There is no safety issue with your plan but, placed in the ground, the planter may rust away to nothing sooner than you expect.

A. Hi, Lance. We relocated your posting to this thread which probably answers it for you. It is safe.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


May 7, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I'd like to grow an herb garden outside my kitchen door. Crate and Barrel has a "Wide-rimmed planter in lightweight, zinc-finished galvanized steel" with an over-the-railing plant holder that fits over my aluminum railing - very convenient to run out the back door and grab what I need while cooking. And the plants wouldn't take up space on the very tiny patio.

Is there any reason to think that this zinc-finish on galvanized steel could leach toxins into the soil, and then into the herbs? The planter is made in Vietnam. I am somewhat leery of the safety of food related items imported from China or outside the US. If there is the slightest chance of toxicity, I won't use it.

Mary McShane
gardener - Westfield, New Jersey, USA


Galvanized Planter

May 7, 2012

A. Hi Mary.

We appended your inquiry to a similar thread which should help reassure you about galvanized planters. On top of that, your planter is sold as a planter, i.e., it is designed for the purpose, which should offer some indeterminate extra amount of assurance compared to using something that wasn't designed for the purpose.

But with cadmium in children's jewelry that was sold in Wal-Mart, lead in the paint of kids' glasses given away at McDonalds, antifreeze in the dog food ... to require that there not be "the slightest chance of toxicity" is asking too much. Nobody can promise that, but I think we can say that it will be safer than using imported herbs :-)

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


45056
May 17, 2013

Q. I have read a lot of answers regarding the safety of galvanized aluminum planters. My question is, what about galvanized aluminum sheets? I saw a raised garden bed on Pinterest made from a wooden frame but on the sides they used galvanized roofing material =>

Would that be just as safe as planters made from galvanized aluminum? I have the same concern that over time the zinc or other metals would leach into the soil. However this would be for a flower garden and not vegetable garden, but the planter would make a nice raised vegetable garden as well...

Roger Ross
- Manchester, Connecticut


May , 2013

A. Hi Roger. Aluminum has nothing to do with this. Aluminum is never galvanized; these sheets are made of steel dipped into molten zinc.

This is just an opinion-based public forum. I certainly don't expect that any epidemiologist will ever, ever conduct a proper double-blind longterm study of vegetables grown in galvanized planters vs. vegetables grown in other containers. But again, zinc is an essential nutrient, not a toxin. And if you are not doing a soil analysis of the dirt that you are planting the vegetables in, or the wood that the frame is made of, or the fertilizers and plant foods you may be adding, trying to estimate whether there may be a slightly high zinc level in the soil as a result of using a galvanized planter box seems to me to be focusing on the inconsequential. I'd say study the origin of the seeds or seedlings, and any insecticide or herbicide use. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


June 24, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hello, I have recently bought some large old galvanised drinking troughs. The idea I have is to fill them with soil and plant them up with edible fruits and vegetables. Should I be concerned about the cadmium and zinc leaking out into the vegetables? I have noticed that the bottom of the inside of these troughs is showing signs of rust so should I be concerned that the coating is breaking down and leaching into the ground also? Is it best to use some sort of liner and what sort do you suggest is the safest to use? Thanking you in advance for your advice. Regards David

david lee
- salisbury wiltshire England


June 25, 2013

A. Hi David. There will be no cadmium is a drinking trough, and the zinc is an essential nutrient.

You may need to be concerned about their durability if they are already rusting -- so you may want to paint them. But no worries about toxicity. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


June 26, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I am trying to find out if there are any long-term issues with growing edible plants in galvanized steel stock tanks or garbage cans. Does galvanization only use zinc in the coating (in which case I don't have much concern) or does galvanization also involve other "heavy" metals, like cadmium? I understand that after several years, the coating will begin to flake off, so I am concerned about uptake into the plants, and hence into the edible parts of the plants. I want to plant in large metal containers to confine the spread of the plants, so it is for long-term perennial use.

Can you compare if pre-galvanized steel or post-galvanized steel would be better for this purpose?

Robert Healey
- Norwich, New York, USA


June 26, 2013

A. Hi. Galvanizing does not use cadmium. There may be small amounts of lead or chrome in galvanizing, but everything is relative, and galvanized containers will be safe to plant in. Post galvanized are probably heavier and therefore longer lasting.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



Galvanized Sheet and Composting Rack

April 22, 2016 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Dear Sirs, I am interested in building an above-ground composting rack. One component will be corrugated galvanized sheet metal. Eventually this material will rust. In your best available opinion will the leaching metals be concentrated enough to be harmful. I know that is a broad question, but simply looking for some general guidance. Thanks in advance for your help. Scott

Scott Steinbach
- Waco, Texas


April 2016

A. Hi Scott. No.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


March 2, 2018

Q. I saw an ad for a space saver strawberry garden. It is made of 3 stacked rings made of corrugated aluminum bands. Is it safe to plant vegetables in aluminum containers?

Linda Griffiths
Home gardener - NORTON, Ohio United States of America


March 2018

A. Hi Linda. There may be more aluminum in the soil in the strawberry garden than could dissolve from those bands in a lifetime. Aluminum is over 8% of the earth's crust, and the 3rd most abundant element of the earth.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


March 3, 2018

thumbs up sign  Thank you very much for answering my question

Linda Griffiths [returning]
Home gardener - NORTON,Ohio United States of America



April 10, 2018

Q. Hi! I am planning on using galvanized mesh cloth to line my raised beds. It is steel galvanized post-weld.
Should I be concerned at all about metals leeching into my soil over time? I understand that acidic soil may leach the zinc. Would it be able to leach toxic levels? And I'm worried that the weld is lead based. Is that a possibility? And if so, does the galvanization process seal it in? Would I need to be worried about lead leaching over time as the galvanization degrades?
Or I guess, what would be your suggestion of what to look for in gardening mesh that will be underground to control gophers in a veggie garden.
Thank you!

Jenny Ladd
- Atlanta, Georgia USA


April 2018

A. Hi Jenny. I don't understand your question about lead-based welds. To my knowledge steel is welded with steel welding rod.

What I would look for is any product designed for the purpose. The chance of you being harmed by it then is quite small; it is when we re-use things that were designed for other purposes that we must worry about what they might be made of. But even galvanized wire cloth may not last more than a couple of seasons underground.

45056-2

The zinc "leaching" question has already been answered many times already on this page; if you are not confident about internet opinions you can obtain white papers on the subject =>

Luck and Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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