Is treated lumber safe for building raised bed vegetable gardens?

After posting a photo of my new raised bed garden frames in last weeks “what did you do to prep this week” post, I received several emails from readers asking if I had built my frames using treated lumber and they then proceeded to inform me of the health risks involved with  the use of treated wood in my garden.

One readers email gave a dire warning to the effect that I would surly die from the first bite of produce taken from the garden if treated lumber was used to construct the frames because arsenic would leach into the surrounding soil and into my food, then kill me when I ate it…

I would like to thank you for your concern, it is appreciated and noted. And to answer the question, yes, my new raised garden bed frames were built using treated lumber but I’m now concerned about it… not even a little bit.

Years ago many folks including several national magazines and agencies suggested that it was “possible” for small amounts of chemicals to leach into the soil from treated wood when that wood was used to build frames for a raised bed vegetable garden. The main health worry was arsenic, because treated lumber at the time contained arsenic that was used in the treating process.

According to this article from University of Missouri Extension Office:

“Pressure-treated lumber uses CCA (chromated copper arsenate) or ACA (ammoniacal copper arsenate) as a preservative. However, studies done by Texas A&M Agricultural Extension Service showed insignificant movement of these compounds into surrounding soil. Pressure-treated lumber has no proven effect on plant growth or food safety.”

But, this is all a moot point because arsenic has not been used to treat lumber for residential use (with the exception of some woods for marine purposes) since December 31 2003.

So the admittedly small risk, associated with using treated wood before that date to construct raised vegetable garden beds and frames have been further removed with the elimination of  arsenic in the treating process.

According to Becky Wern, Master Gardener with the Duvall County Agricultural Extension Service and the University of Florida:

Today’s pressure treated lumber “is safe to use around children and animals and for gardens with edibles.”

Also according to The National Gardening Association:

There’s still a lot of controvery about using treated wood for vegetable gardens. There was a time when pressure treated lumber contained arsenic (CCA) and was not considered safe for use in raised vegetable gardens because the arsenic leached out into the soil. The newest method for treating wood is Micronized Copper Quaternary (MCQ).

It is chemically different than the old CCA treatments. It is made of tiny (micro) particles of copper. These particles are forced into the wood cells or pores during the pressure cycle. Once in, they stay in, also forming a barrier keeping in the quaternary. The leaching of chemicals out of MCQ is practically non-existent and using the treated lumber for a vegetable bed is safe because the chemicals do not leach out into the soil.

However if you’re still worried then don’t used treated wood to frame your raised vegetable gardens, it’s that simple. Or line the inside with heavy plastic (but then I’m sure some will worry about the plastic “leaching” stuff  into the soil) or line the sides with rock or some other material.

Comments

  1. Whew, I’m safe! My raised beds are not made of treated lumber. Mine are pure man made plastic fake wood. I’m sure I don’t have to worry about the hundreds of chemicals in these things!

  2. riverrider says:

    THANK YOU!!!!!!!!!!!!

  3. Backwoods Prepper says:

    Had me skeered. I have been using treated lumber for my raised beds since 2007. But I did blame it for killing myh tater plants in a tater tower one year. I had been using old tires and decided to build some extra out of wood. The two I built had hardly no taters but my old tires had plenty. I’m sure it was the would but maybe not.

  4. I remember when they were built with railroad ties.

  5. Thanks for all the useful information, buddy. Always good to have all the info we can get about these things.

    Staying informed is very important in these times, I think!

  6. Shades of Green says:

    I built mine out of treated lumber but my DH lined them with a heavy duty rubber pond liner. It is the same liner we have used in our pond and my fish are nice and healthy. I did leave the bottoms free for drainage and the gardens grow great.

    • Encourager says:

      Shades of Green, that is exactly what we did – lined it with rubber pond liner. But we did it so the moisture would not evaporate as fast. We lined the bottom with coated hardware cloth with two layers of landscaping fabric to prevent the dirt from dropping through. The bottom also has cross pieces to prevent sagging. We used treated lumber for the legs but non-treated lumber for the sides. Our raised beds are hip-high so us older folks don’t have to bend over so far to weed!

  7. I use copper treated wood as well and not concerned for my health. I’m more worried about the copper fungicide in the wood throwing off the soil ecology. These little guys are really important for plants: http://en.wikipedia.org/wiki/Mycorrhiza

  8. For one thing the leach rate has to be very low or pt lumber would rot fairly quickly. Another thing is I don’t think gravity would allow the chemicals to leach sideways so they would probably conentrate an inch or two on the bottom and sides of the soil. If you have a 2×12 for the sides I don’t think most garden vegatables have a root system that would reach to the bottom and sides of a bed unless they were planted right on the edge of the bed. I am sure we get way more into our system from just the environment we live in and the crap big ag sprays on the food anyway. Hell some of us may have enough chemicals and preservatives in us already that we don’t need to be embalmed when we go !

    • SurvivorDan says:

      I have been treating my glorious body with alcohol for many years to ensure adequate pre-embalming so my exs can keep me around for their viewing pleasure.

      But seriously folks, I appreciate the information and the common sense approach to the chemical ‘contamination’ phobias that, in this case, have no basis in fact. Or pose such a minuscule likelihood of passing any toxicity that the benefits out weigh the risks.
      That said I do appreciate the purists. My great aunt Peg was a very strict organic gardener (never used treated lumber or chemical fertilizers). Her produce was delicious and her and my uncle lived well into their nineties. My uncle regularly replaced her raised bed garden frames when necessary.

  9. I’ve been using treated lumber for years and have had no problems. If I used untreated lumber the termites would have it destroyed in a year or two. Untreated lumber in heavy clay soil breaks down very quickly also.

    • Dan
      I’ve seen people use a 2×2 or 1×2 strip along the bottom of their wood boards as a sacrifice, when it rots in a year or two just replace the small strips.

    • I agree Dan. I use untreated lumber and I have to replace sections every year. I would say on average, the untreated lumber in my yard lasts about 4 years before it is worthless.

      I keep saying I am going to replace them with something else, but I compare the price and the untreated lumber is the cheapest even with the replacement costs. Although, I know I won’t be able to replace them when the world ends.

    • Unless they used something root resistant like cedar…

  10. I’m not sure about building your raised beds with PT lumber, but I know that you DO NOT EVER burn it. I know of people who used it for campfire wood. She nearly died from breathing in the smoke from it, and he did.
    I know “they” also say never to use pallets for food storage, if you don’t know what they were used for previously, because they may contain chemicals.
    So….I guess I might think twice about using pressure-treated for raised beds.

    • I wish I had not burned it a few years ago. Made me sick for weeks, and I acted very oddly. Didn’t think anything of it until I read online that you weren’t supposed to burn it.

      oops, guess I should be lucky I’m still alive.

  11. junipers says:

    We used “regular” non treated wood around our garden beds almost 10 yrs ago, and they have all rotted & need to be replaced. We plan on using treated lumber to build raised gardens this year. Now, all we have to do, is to train our wannabe Border Collie, Riley to stop playing and digging in the gardens. We had to put a wire fence around our garden last year. (She loves to eat carrots!) Thank you for taking time to share valuable information with us. It is greatly appreciated!

  12. I didn’t use treated wood for my raised garden but I did coat it will with linseed oil to extend the life of the wood.

  13. peanut_gallery says:

    I had used treated lumber almost 30 years ago, they finally started to rot, so when I re-did the raised garden I switched to manufactured stone. I didn’t think that I would be up to re-doing the whole thing in another 30 years. A little more expensive, but permanent. I will never have to worry about it again.

  14. ladyhawthorne says:

    And we all grew up with lead paint and survived that too.

    • ladyhawthorne,
      We werent’ eating the paint, and when it was eaten it caused many health issues. Breathing the particles isn’t good for you either, like when sanding or cutting lead painted or treated wood.

  15. ozhillbilly says:

    Thanks for this information M.D. I’ve always been concerned about using treated wood around the garden so now I know. Unfortunately my whole backyard is surrounded by a 25 year old treated fence. It is also where my garden is. It’s not good news but we are exposed to so much these days anyway I guess one more thing won’t matter???

  16. tommy2rs says:

    When I used raised beds (from the 80′s up until a couple of years ago) I never could figure out why folks put lumber around their beds anyway. I always just loosened the soil and shaped it up into beds with a shovel. It stayed in place just fine and the produce didn’t seem to know any better, it grew thick and lush. Since then I’ve gone back to flat earth growing for the main garden so I can use a wheel hoe for plowing, planting, seeding and weeding. Much less lifting and bending involved for my arthritic back and hands. Even got a hitch for it so if the going gets tough while plowing I can use the riding mower (with The Boss driving) to provide some extra ooomph.

    • tommy2rs;
      I know why we have raised beds for the garden, our soil is good old rock. Very little soil, and I do mean next to no dirt and if you find dirt it is a blessing. We joke about sharing “our soil” with the other neighbors, we do not want them to feel left out. We have learned over the years to make the garden beds narrow (not over 2-3 feet wide), and what ever length you have room for. Saves on your back, and you can rototiller the soil.

  17. Years past they even warned against breathing the dust made when sawing treated wood. I’m glad they changed the chemicals for treating the wood. I’ve made raised beds from it as well here in Louisiana ,the termites are the size of rats and they are just waiting for an untreated piece of wood to hit the ground.

  18. The information you provide pretty much jives with everything I’ve learned over the years. I know several people who’ve also used railroad ties with no ill effect. It’s largely a non-issue.

    The REAL issue is one of how long will the beds last. I’m in the south and most treated lumbers will deteriorate in as little as 10 years including red cedar. Composite (a bit ugly) and borate treated lumber (expensive but nice) will typically last much longer and have are often favored by those who care about evil chemicals.

    If you really want to do it on the beautiful side without any concern for those terrible poisons waiting to attack your children and pets, then go with masonry or stone.

  19. k. fields says:

    Personally, I don’t use it.
    I’ve read all the reports on how safe it is and how it will have no detrimental effects but I always ask these questions; Would I use PT wood to build my picnic table? Would I use it to build children’s playground equipment? Would I build crates out of it to store fruits and vegetables in? Would I use it to build an unlined water tank?
    If I ever get to the point where I can answer yes to those questions, I would use it to build garden beds, but not before.
    But everyone is different.

  20. Nan in NC says:

    I’m living proof that pressure treated lumber does not kill you after the first bit of veg harvested from a raised bed built from it! I’ve been doing it for 20 or more years with no ill effects. I know there will be folks who say “Well, it’s the long-term effects that harm you.” My answer would be “How long is long-term, and at my age should I really worry about it?” I use landscape timbers for mine, stacked 4 high, since the soil here is really bad.

    • Totally agree with you, Nan.
      Perhaps the Pack should be more concerned bout whats in the dirt and water used in your garden? EPA.gov….follow links to your state then zip code. Keep the link bookmarked, if you’re looking for a Bug Out location.
      Using Heirloom seeds? No…what’s in your seeds?
      What about the chemicals in all the packaged food in your pantry?

  21. “then I’m sure some will worry about the plastic “leaching” stuff into the soil”

    Then they should avoid soy products.

  22. I use use treated lumber in my raised beds beds and I don’t have any trouble. I I do have this stutter that that started about 3 years ago. Come come to mention it thats when I started using using the treated lumber for for raised beds. hmmm

    • Copperhead says:

      Thanks, gil, for my giggle of the day! I thought your computer had a glitch in it at first. Happy gggggardening!

  23. Copperhead says:

    Thanks, M. D., for all your research into this. I have used raised beds for years.

  24. Sw't Tater says:

    I already have tin and old, old concrete blocks…and that is what I’m using. But there were some bad incidences of arsenic effects on ppl who were building using and breathing. I am glad this has been addressed. as we will have to do some building soon..

  25. I built all mine out of white cedar, 2′hx4′wx20′l about ten years ago just because of the ACC stuff. Still have about 30 years to go before these start to rot. Or so I’m told.I screwed a 2×4 to the outside of the top lip and then put on a 6″ Trex bullnose decking seat all the way around. Works great. I either till it by hand with a 2′ long 6 tined clam rake, or a Mantis gas tiller.

  26. It still contains arsenic That’s one of the reasons it is used out doors Doesn’t attract bus or terminates There is a water proofer in the wood also. It is highly toxic also

  27. The old arsenic type was more dangerous as it would leach into the soil and then be taken up by the plants, which then were eaten by you. Over time it could build up in your body causing health issues. Newer non arsenic is safer. Using old tires may also be dangerous as they break down over time. Now, it may take large amounts over a long time to add up to dangerous levels in your body , but why take the chance? Using these components will make the crops grown not suitable for ‘organic’ labeling. It would be like using plastic buckets or barrels that contained these compounds to store food or water in, no matter how much they are washed there’s still potential for contamanation.
    One other thing to consider is the soil. Good organisms in the soil will be harmed and may cause growth or development issues with the plants.
    You will most likely be fine, but issues with liver, kidney damage, immune system dysfunction, or mental development with children should trigger at least an inspection of the plants and soil.
    It’s funny how all the studies initiated and funded by the lumber companies never found anything ‘ signifacant’.
    I’ve always used rocks to ring my garden beds to hold the soil, no chance of chemicals, keeps the heat at night, provides nice little homes for the toads and garter snakes so they can gobble up the slugs, bugs, and mice.

  28. I bought a picnic table made of the old treated wood. All the grass died underneath. No, it was not from lack of sun. I got a picnic table of the new treated wood and put it in a different place. The grass under it died too. The grass has not grown back where the first one sat. There is lots of sun on the table and under it late in the day because it is in full sun. So, something should grow there, weeds at least.

    Sure, lots of people survived lead paint. But, how many IQ points did they lose? Some children were retarded but they are not on here to say lead paint is dangerous. The sawdust from treated wood is to be avoided at all costs. Read the directions and warning on the new stuff. Just because the government says anything is GRAS, doesn’t mean that it IS safe.

    I remember Thalidomide. I don’t trust the government and the companies that control the government.

  29. Thanks, M.D. I have been using treated lumber for raised beds for 30 years. No such thing as soil in NW Arkansas. The most reliable crop here is the annual rock crop. Clean out the garden this year and next year a new crop double the size of this year’s crop is the usual. Raised beds solve the problem. Back in the days of arsenic in treated wood, I used the plastic liner with drain cuts. Now, I do not bother. Just remember to use man made growing medium in raised beds. It is amazing how well plants grow in the beds.

  30. DocJ, I could use them rocks you are sprouting, neighbor. Nada here but clay with no rock.
    I have rr ties around the asparagus bed, treated Lumber beds, annd old tire planters. the air we breath is more dangerous. Remember, we drank untreated well water from garden hoses when we were kids. A zillion years ago. We are still kicking.

  31. MD Please get your soil tested as time goes on because even a small
    amount of extra copper can create severe depression in people.
    I am also a Master gardener . Arlene

  32. When I built my first raised bed about 5 years ago, I heard the warning about PT lumber. I searched online, found a report from an extension service. Their study found not significant leaching and what little was found was in root crops grown within 2″ of the lumber. None in the vine veggies or root veggies away from the edges. So if you are concerned, just avoid root veggies within 2″ of the sides.

  33. Thanks for the links MD. Many years ago we worked for a few farmers
    who didn’t realize (nor did we) the problems with some materials.
    We creosoted over a mile of fencing.(now its a known carcinogen and we would not touch it) Asbestos has given my husband mesothelioma.
    I believe a combination of many pesticides and chemicals are contributing to many types of cancers. Yes you will most likely be fine
    but please watch the copper because its very minimal in vitamins and minerals for a reason. Enjoy your garden !!! Arlene

  34. breadmomma says:

    I used old brick and cinder block and built three large raised beds waist high…the old back plus I plan on staying here for many years…works like a charm…plumbed it with water, and have electricity close for lights and can cover with a nice hoop house…plus I don’t have to bend and can sit on the edge to harvest…few weeds, hardly any critters and all the food I want…beats the heck out of the wood ones that needed constant attention from our nice wet Oregon rain…

  35. charlie (NC) says:

    When I was a kid on the farm in the 50′s the primary chemical
    we used in the garden for pest control (bugs and worms) was
    lead arsenic. Of course they eventually outlawed that but not before
    it killed me………….. oh wait. I’m still here….50 + years later.
    My point is that the garden dust we put directly onto the plants is
    a lot stronger than anything that leaches out of the wood. No arsenic now days but the new chemicals still kill the bugs. I

    I heard that whole treated wood arguement here on the coast when the worry warts and do gooders wanted to do away with it because it might
    harm “aquatic life”. I’ve seen treated dock pilings and sea walls (built with lumber treated for immersion. much stronger than what you get at lows) with barnicals and shell fish growing on them within a year of them being placed in the water.

    If you need something to worry about and live in a house built before about 1975 with painted walls or exterior trim and you’ve been planting tomatoes around the house, under the drip line, then worry about lead poisioning.

    IF I was worried about using treated lumber, I’d wrap it with tyvek or one of the other brands of “house wrap”. It allows vapor to pass through but not water or leachates.

  36. AZ Rookie Prepper says:

    I’ve used both treated and untreated wood for making raised beds. Neither one will last forever, and my concerns over health matters dont let me worry about the possible leaching. Much more concerning to me is the HBPE chemical contamination from using plastic “tupperware” type food storage containers in a microwave oven. Apparently, heating those releases chem’s into your food….what next? Eggs are no good? Charbroiled steaks are unhealthy? I say EAT and enjoy.

  37. When I was getting ready to start construction on my raised beds I ran a whole lot of numbers. I decided that I didn’t want to keep building my beds as time went on so I opted for a one time purchase while I am making decent money. I built my raised beds out of 8x8x16 concrete blocks and they are 3 blocks high (on the low side of the slope). They also have a 1 inch cap block which makes for a wonderful place to sit your coffee, produce, or your butt to take a break and enjoy the gardens. According to the numbers and my situation… it was actually cheaper in the long run to just buy the concrete blocks up front vs. having to rebuild wooden beds 3 or 4 times.

    I also set up my beds to be “old folk” friendly cause one day… I may be motoring around in a 4×4 power chair to do my gardening.

  38. My town water supply has high arsenic levels anyway. Every time I water the plants, arsenic is accumulating in the soil. Oh joy!

  39. lee in az says:

    the big problems with the newer treated lumbers are at the manufacturing level and the disposal level– there is no safe way to get rid of scraps or wornout treated wood except to landfill it.

    if you don`t thing treated lumber wears out, wait awhile. the homecenter quality you most commonly find is designed for sitting on top of a nice dry concrete foundation covered by a roof or neatly painted. give it contact with air and soil and humidity and it may be gone in 10 years.

    i stopped reading Mother Earth News when they had an article about the benefits of burning treated lumber, or maybe it was wood soaked in used motor oil.. i also gag when Sunset magazines advocates using redwood.

    The best bet for raised beds is masonry, with local stone being the cheapest and environmentally most benign. I`ve had good luck with old bricks set up dry, although I am slowly reworking them with mortar for my convenience.

  40. Barb Russel says:

    Please note WHO is saying this is safe. Extension, government sources, and universities are for the most part bought and paid for by the Monsanto industry crowd. As a counterpoint to industry-paid-for expertise in this area, please read http://www.gardensalive.com/article.asp?ai=989. Same deal as GMOs and the FDA.

  41. I have a bunch of left over brick that I will be using. Here in South Texas it’s all trial and error. Mostly error. So far I’ve grown a bumper crop of rock and garden store receipts.

  42. What about painting the veggie box on the inside and out with just normal water based paint? Would this seal in any toxins or leach them out of the paint too? I have a partner who is worried about using the elevated garden bed I have just constructed whether I paint it or not…somebody help as I don’t want to throw it away and need some evidence to put her mind at rest so I can paint it and start growing veggies and herbs in it.

  43. Ed Williams says:

    Don’t worry, all that other harmful stuff we knowingly and willingly swallow will kill most of us long before the chemicals in treated wood could have much effect. We recently started a vegetable garden at our church to help a meals-on-wheels program. I asked several agricultural experts at universities and the extension service about using treated wood for raised beds. They all said today’s treated wood is safe to use.