Is Pressure Treated Wood Harmful to use in the Garden?

Is Pressure Treated Wood Harmful to use in the Garden?

When selecting wood to make raised beds often people will recommend avoiding pressure treated wood siting the preservatives may be harmful. In this month’s installment of our testing garden assumptions series I thought I would put this to the test.

Dead wood if left to the elements will decompose. If the wood has been used in a raised bed it is probably not favourable to have the bed decay quickly.
There are two solutions to this. The use of a hard wood or cedar will slow the decay process but in most areas these woods cost a lot.
Alternatively more common lumber can be treated and preserved in order to slow the decay process.
In recent decades the three most common treatment processes include Creosote, Chromated copper arsenate (CCA) and Alkaline Copper Quaternary (ACQ).
Both Creosote and CCA were abandoned in 2003 voluntarily by industry in North America for the sale to the general public. This was done as there were concerns over the hazard of hydrocarbons and heavy metals used to preserve the wood. [1] [8]
ACQ treatment remains available in most lumber yards.

Our hypothesis today is that pressure treated wood may be harmful if used to build a garden.
ACQ treated lumber is most commonly used residentially. The method uses Copper with and an companying biocide to help resist the decay process.
Lets take a look at both biocides and copper to see if they are potentially harmful in a garden.

Biocides are any chemical or microorganism that deters harmful organisms. Biocides are used in medicine, agriculture and industry such as forestry.
Most commonly in pressure treated wood the biocide is DDAC Didecyldimethylammonium chloride. [7] It is also commonly used as a disinfectant for surgeries and restaurants.
When tested for leaching in an extreme environment researchers showed leaching results into the environment between 0.19 and 0.22% well below the industry allowable standard of 4% [4]These extreme conditions were designed to facilitate leaching and are highly unlikely to be replicated in your back yard garden.

References:
[1] https://en.wikipedia.org/wiki/Wood_preservation
[2] http://www.ncbi.nlm.nih.gov/pubmed/23295179
[3] https://en.wikipedia.org/wiki/Didecyldimethylammonium_chloride
[4] http://pubs.acs.org/doi/pdf/10.1021/es0493603
[5] https://en.wikipedia.org/wiki/Copper_toxicity
[6] http://ceqg-rcqe.ccme.ca/download/en/263
[7] http://www.epa.gov/oppad001/reregistration/cca/acq.htm
[8] http://www.epa.gov/ttnatw01/hlthef/cresols.html
[9] http://soils.wisc.edu/facstaff/barak/soilscience326/listofel.htm

50 Comments

  1. Britt My on May 25, 2022 at 8:34 pm

    This is just the video I needed !!! I had extra wood left over from doing my fence and I had wanted to use it to start my Gardens but was wary about it . this has been a very informative and easy to understand video

  2. K E Carter on May 25, 2022 at 8:34 pm

    Using Treated Lumber in Raised Garden Beds https://www.youtube.com/watch?v=NzL6gLKUq_4

  3. Nutrition Facts on May 25, 2022 at 8:37 pm

    you areso appreciated

  4. Caleb Tabor on May 25, 2022 at 8:38 pm

    Fantastic breakdown! Great video.

  5. Joshua Lehman on May 25, 2022 at 8:38 pm

    Excellent!

  6. Psylacus on May 25, 2022 at 8:40 pm

    Thank you for this video so informative and not full off superstition and old wives tales. I have been on the fence with what lumber to use. I don’t want to use the standard white wood and tends to break down in 5 years or so here in Utah. I am looking at using a pressure treated hemlock such as: https://www.lowes.com/pd/Top-Choice-Common-2-in-x-8-in-x-12-ft-Actual-1-5-in-x-7-25-in-x-12-ft-Pressure-Treated-Lumber/50017306

    However it says not treated for ground contact? Not sure if I can find anything that is meant for ground contact? Any suggestions? Is this fine. Lastly if all else fails lining it in a plastic (only the sides) would stop leaching almost entirely?

  7. Brian S on May 25, 2022 at 8:40 pm

    I was wondering if you could just paint the inside of the lumber with some clear paint to act like a barrier from the wood. Thanks, great video. Brian

  8. Kevin Christian on May 25, 2022 at 8:47 pm

    Exactly what I needed!

  9. odd petrichor on May 25, 2022 at 8:47 pm

    Great video! Very helpful.
    Where might MCA treated wood fall into this analysis I wonder?
    Keep up the great work!

  10. M B on May 25, 2022 at 8:48 pm

    Buy cedar and stop worrying it. $100 for a raise bed that will feed you for years and making you healthy isnt that expensive at all.

  11. Kyle Dewar on May 25, 2022 at 8:48 pm

    If i build a brown treated raised garden bed and install a liner inside the box will that be safe

  12. Simon Inga on May 25, 2022 at 8:49 pm

    ACQ is harmful to life and health, a carcinogen and damages the liver, kidney and nervous system.
    Acute Toxicity (Dermal), Category 4
    Acute Toxicity (Oral), Category 4
    Skin Corrosion / Irritation, Category 1
    Eye Damage / Irritation, Category 1
    Skin sensitizer, Category 1
    Specific Target Organ Toxicity – Single Exposure, Category 1 (kidneys and liver)
    Specific Target Organ Toxicity – Single Exposure, Category 3 (respiratory system)
    Specific Target Organ Toxicity – Repeated Exposure, Category 2 (kidneys, liver, lungs, and nervous system)
    Hazardous to the Aquatic Environment – Acute Hazard, Category 1

    ACQ Preserve and Preserve Plus Pressure Treated Wood –
    http://treatedwood.com/uploads/Preserve_Plus_MSDS.pdf

  13. Chewning Witmer on May 25, 2022 at 8:49 pm

    Woodglut has a lot of designs to choose from.

  14. M R on May 25, 2022 at 8:53 pm

    This was brilliant. Thank you!

  15. z1522 on May 25, 2022 at 8:54 pm

    While this should reassure folks about the use of commercially treated wood, keep in mind avoiding DIY materials like used motor oil, which many use in fence post installs, and which could end up in proximity to a garden bed. Another more complex issue is whether some plants concentrate certain materials like selenium, such that safe soil concentrations might still result in higher levels in the actual consumed produce.

  16. Antoine on May 25, 2022 at 8:58 pm

    Good research! this is the kind of youtube video that we need!

  17. Lost Beagle on May 25, 2022 at 8:58 pm

    Assuming that I have treated lumber for a raised vegetable garden and want to avoid all leaching into the soil, what type of liner should I use and where can I get it? I’v been told that 8 millimeter plastic, rubber or pool liner would work but I don’t know for sure. What do you recommend?

  18. Janiqua Qua on May 25, 2022 at 9:00 pm

    I made my 4 beds with treated lumber and I’ve always wondered if the risk was high/low or non-existent, I couldn’t find a definitive answer anywhere so just fired ahead and hoped for the best, thank you for this 👍

  19. J Glazebrook on May 25, 2022 at 9:01 pm

    I would like to see this same test with CCA treated wood. Because from my reading, it was the general public fear of the Arsenate (arsenic) rather than the science of Chromium being a bonding agent of arsenic to the wood that caused it to be banned.

    In Australia CCA treated pine is still allowed to be used. CCA treated wood elsewhere is allowed to be used for structural material where it gets touched by hands much more regularly.

    So my question would be, is CCA treated would showing leaching to the extent that vegetables take it up?

  20. Drew F. on May 25, 2022 at 9:01 pm

    Thanks for this video. Any thoughts on using treated pine and lining the beds with plastic before filling with soil?

  21. Louis Pacheco on May 25, 2022 at 9:03 pm

    Could you please comment about Fly Ash used in cinder blocks for vegetable garden beds and their possible Toxicity ?

  22. Naiyo on May 25, 2022 at 9:06 pm

    You my friend are the only person on Youtube that explained this subject vividly with facts. Thank you

  23. April Moore on May 25, 2022 at 9:07 pm

    Wow you are so amazing. Thank you so very much!

  24. Ded Ede on May 25, 2022 at 9:09 pm

    This video sounded like it was produced by a PR company and "scientists" for a cigarette of big tabaco. Lol

  25. John Henry Sheridan Music on May 25, 2022 at 9:10 pm

    Thank you for your friendly video!

  26. BSAsVlogz on May 25, 2022 at 9:10 pm

    Hi mr. Alberta would you mind answering my question?…for the sake of my research please…here is the question…..Is pressure treated woodchips dangerous for my plants if I mulch it or if I put it in my compost?

  27. josh russo on May 25, 2022 at 9:11 pm

    I appreciate the in depth information… Thank You

  28. Our Backwoods Homestead on May 25, 2022 at 9:11 pm

    I got a bunch of free fence wood 5/8 pickets 6 ft long.
    Its really old and dried out would that be ok to make raise bed frames?

  29. Bestbuilder on May 25, 2022 at 9:11 pm

    Thank you for the research. I would have hoped you would have taken a control from the middle of the yard also, so that there would be a real example of the chemicals (not just copper) difference between the bed itself and the area. Of course, we can go a bit crazy trying to define a true control, at some point you just have to go with what time and money, allows.

  30. mike johnson on May 25, 2022 at 9:12 pm

    Thx dude. I was planning on cedar anyhow.

  31. Hunter Phung on May 25, 2022 at 9:13 pm

    Should I use liner to protect wood?

  32. Nutrition Facts on May 25, 2022 at 9:13 pm

    does it get absorb by plants?

  33. Phillip Esch on May 25, 2022 at 9:14 pm

    Awesome video! Thanks for all the work you did!

  34. Jill Marie Hungerford on May 25, 2022 at 9:14 pm

    Hi, I’m concerned because I sprayed the inside of my planter box with Copper-Green to preserve the wood (before I learned that redwood has its own natural preservatives).

    The smell was SO bad, I had to immediately wash my hands, hair and clothes! It’s not the 10% copper naphthenate I’m concerned with as much as the 90% Inert ingredients, which include petroleum distillates. Three days later and the smell is still very strong, and now Im concerned about planting my edibles in it!

    Do you or any readers here have any experience with Copper-Green and ideas of how I can remove or dilute some of the chemical residual (other than sanding it down)?

  35. suffolkshepherd on May 25, 2022 at 9:15 pm

    First video and I have subscribed. Gardener Scott suggested this channel.

  36. puneet gill on May 25, 2022 at 9:16 pm

    The lady in the home depot said me to use cedar wood only !!! It’s bit expensive than the treated one only.

  37. K W on May 25, 2022 at 9:17 pm

    Hmm, great video and nicely presented but I do have a concern. How do we know that the control hasn’t been impacted by the leaching? A better control might be to use soil from a raised garden that doesn’t have any pressure treated wood at all. You’re also mentioning that it’s only harmful if at toxic levels– but I wonder if things like copper accumulate in our system, especially over time? Things to consider.

  38. Scott O'Keeffe on May 25, 2022 at 9:18 pm

    Good to see someone using proper scientific methods to answer some of these horticultural questions. Well done!

  39. Brian Duguay on May 25, 2022 at 9:23 pm

    So I think what remains is that the PT lumber, even if it says it’s rated for ground contact, still will eventually break down. So if you want them to last longer, then using an HDPE (type 2) or LDPE (type 4) plastic barrier might be a smart move anyway. Also being sure to use a ceramic coated screw because the copper will react with any disimilar metal fastener and corrode it so the joints weaken faster than the wood. The sun can do quite a bit of damage to PT too. They say you can put a U/V protective finish on it about 6 months after it’s had a chance to dry out.

  40. johnny le on May 25, 2022 at 9:25 pm

    Research paper quality, very good.

  41. Robert William on May 25, 2022 at 9:25 pm

    Should have made the control outside the garden or from beds without PT lumber. How do you know your soil or your watering methods were introducing the copper?

  42. JavaBro on May 25, 2022 at 9:25 pm

    Well, being new to gardening, it looks like I’ve made a pretty bad mistake; I stained my garden beds with a sealant/stain when making my garden beds. Is there anything I can do to still be able to use the beds, such as lining the wood with a liner, or by placing a more suitable container within the beds to be planted in?

  43. Mike G on May 25, 2022 at 9:26 pm

    At 4:00 you are sitting next to railway ties used as a raised garden bed. This is dangerous as railway ties were treated with harmful chemicals. At least that is what my findings on the internet have found…

  44. Chris Birck on May 25, 2022 at 9:26 pm

    Thanks for the video Stephen!

    I would like to use pressure-treated wood for construction of my
    garden, but I plan on using a plastic liner between the wood and soil. I
    have a few questions though:
    1.) Do I have to line the bottom of the garden, even if it is not directly in contact with the pressure-treated wood?
    2.) If so, do I poke holes in the bottom of the plastic so that water can drain from the soil?
    3.) At what depth do I bury the plastic? In other words, how much soil do I
    need to have so the roots won’t penetrate the plastic?
    4.) How thick (what MIL size) should I use?
    5.) How often do I need to replace it the plastic?
    Thanks!
    – Chris

  45. kingbiscuit28 on May 25, 2022 at 9:27 pm

    Thanks for the video, as there is very little real world testing out there regarding the use of pressure treated lumber. I am concerned that the copper decreases over time and possibly the 1st year might have had much higher levels. It would be good to see a time release study, done by a lumber company or university.

  46. Nunya Biznis on May 25, 2022 at 9:29 pm

    Have you done a video on using concrete blocks for raised beds?

  47. Satish Soni on May 25, 2022 at 9:29 pm

    Thanks for taking time and doing this analysis. I guess adding a layer of plastic from heavy duty garbage bag may help isolate soil from leached copper.

  48. Andoniades on May 25, 2022 at 9:29 pm

    Very good unbiased investigating!

  49. Romaine Athey on May 25, 2022 at 9:30 pm

    Quick easy access to many projects with Woodprix plans.

  50. Nicholas Huss on May 25, 2022 at 9:32 pm

    Great video thank u for ur time and the results from the soil samples.

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