Safe wood preservative treatment for raised vegetable beds

Discussion in 'Organic Gardening' started by donnacanadensis, Jan 22, 2009.

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  1. donnacanadensis

    donnacanadensis Member

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    I am starting a new organic vegetable garden and plan to use cedar boards to build the beds. I would like to preserve the wood but don't want to use anything with copper, boron, etc. I heard of Life Time Wood Treatment made by Valhalla on Saltspring Island. They say it's completely safe but I am sceptical unless I know what the ingredients are. Does anyone know what is in it?

    I have consiered using other materials such as bricks, stone, etc. but my veg patch is small and I want to maximize the growing area.

    Any other suggestions would be greatly appreciated.
     
  2. Millet

    Millet Well-Known Member 10 Years

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    Why would you preserve cedar? If you have good quality cedar boards, you do not need any preservative. Ranchers here in Colorado use cedar post for fencing, because they last forever. Cedar is very good against rot. - Millet
     
  3. joclyn

    joclyn Rising Contributor

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    if the boards are SOLID cedar, then they won't need any kind of preservative at all.

    if they're some kind of composite thing, then, yes, i'd say you'd need preservative. i have no idea what would be the prefered product to use in an area where edible plants are to be grown, though.
     
  4. silver_creek

    silver_creek Active Member

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    Cedar in the PNW, even solid 2 x 12's won't last very long untreated. We eked out 10 years (they were disintegrating when we relaced them). Our current beds use a copper (no arsenic) treated board, completely lined with bamboo barrier (30 ml plastic). I would have gone with manufactured stone, until I priced it.
     
  5. greengarden bev

    greengarden bev Active Member

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  6. Ron B

    Ron B Esteemed Contributor 10 Years

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    Unless you do all your work from a standing position you might want to edge with beds with something you can sit on.
     
  7. cowboy

    cowboy Active Member

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    Here is an article about preserved wood products that you may want to read. It's focus is more about the older CCA product with a little about the new ACQ product that you should find in the lumber yards now.

    http://www.taunton.com/finegardening/design/articles/pressure-treated-wood-in-beds.aspx


    The main concern in our neck of the woods was with the CCA product and its use in playground equipment; exposing children to inorganic arsenic. Concern is one thing, action is another. The 20-year old CCA playground equipment in the little park down the street is still there.

    Cedar is not as good as it once was since the harvested trees are much younger and don't have the same resistance to rot as the older trees. Unless we start getting better access to old growth forests, my inclination would be to use cheap spruce with or without a preservative. If you use 2X (2X6, 2X8, 2X10) material in spruce, you should get 15 to 20 years out of it. You get a longer life out of the wood by moving the bottom boards to the top and reversing them so the interiors of the boards are now on the outside. I do this with 1X4 spruce compost bins and get 20 years out of the sides. The bottoms are replaced after 10 years when the sides are rebuilt.

    Good luck.
     
  8. joclyn

    joclyn Rising Contributor

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    hhmmm, learn something new every day!! i thought cedar was impervious to everything - especially water/rot.

    i wonder if teak would be a better solution? or would that not fare well in pnw, either?
     
  9. Millet

    Millet Well-Known Member 10 Years

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    I still would not bother treating cedar. For use as a raised bed, it will last many, many, many, many years. - Millet
     
  10. soccerdad

    soccerdad Active Member 10 Years

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    Here in the PNW, where it normally rains all winter, cedar simply does not last as long as it seems to last elsewhere. Above ground it will last quite a while, but when in contact with the ground it will disintegrate within a decade at the most. For example, I use 1x2 cedar stakes for tomatoes and beans, and after several years the in-ground parts have to be cut off because they look like beavers have been chewing them
     
    Last edited: Jan 25, 2009
  11. RootlessAgrarian

    RootlessAgrarian Member

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    sounds fine to me -- after 10 years, the wood turns into compost and gets recycled into the soil. it only took me and my partner 1.5 days to whack together 4 large raised beds from some recycled-construction-material cedar (good skookum stuff) we got for free (for the effort of hauling it away). call it 3 days labour in all, if you count the hauling and stacking and thinking and cutting and building.

    3 days of labour every 10 years seems very reasonable to me. heck, if our beds last only 8 or 7 years I would still be pretty well satisfied. only plastic lasts forever... and that's (see http://www.cdnn.info/news/article/a071104.html) a very, very bad idea. maybe one of the notions that organic gardners need to jettison is that our human-made structures can, or should, last indefinitely?
     
  12. JanR

    JanR Active Member

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    I totally agree. I made some raised beds out of spruce last fall. I know it won't last forever. I will just replace it when necessary. :)
     
  13. bob 2

    bob 2 Active Member

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    The URL opens on a patent for a lubricating system for aircraft???
    http://www.wipo.int/patentscopedb/e...7064535&QUERY=pa/university+AND+DP/27/09/2007
    I guess you didn't read the patent then?
    Bob
     
  14. bob 2

    bob 2 Active Member

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    Donna:
    I see this one advertised but have no stats on it as yet.
    http://www.valhalco.com/
    I have to replace mine(landscape ties) this year as well as they are about 12 years old.
     
  15. greengarden bev

    greengarden bev Active Member

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    Bob, thank you for pointing this out. The link given in the New Scientist article runs a query on the WIPO patent database, and the result given is obviously not for a wood preservative. I tested the link a couple of time, and the search result was always number 4 of 131.

    Thinking that perhaps New Scientist was a digit or two off, and noticing that the aircraft patent was listed as "withdrawn", I checked a few of the adjacent patent applications and when I returned to number 4 of 131, lo and behold, there was listing for the wood preservative patent. Databases are fascinating, aren't they?

    If you're still interested in this research and you don't want to click in the patent search results page, you could follow the other link given in the New Scientist article, the one for the researcher Tor Schultz. His most recently published paper, about the wood preservative, is there as a pdf.

    FYI, I did read the first page of the patent application and just assumed it was put forward by a company that made airplane technology. A stretch, but possible. Mea culpa. Happy now?

    Bev
     
  16. bob 2

    bob 2 Active Member

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    Last edited: Jan 30, 2009
  17. Ralph Walton

    Ralph Walton Active Member 10 Years

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    There are several different definitions of "organic"; as in "organic chemistry" which considers many compounds that most of us would not accept as organic as in "certified organic".

    The chemical biocides referred to in the wood preservative patent are:
    2-(thiocyanomethy]thio)ben2θlhiazoIe;
    3-iodo-2-propynylbutyl carbamate;
    quaternary ammonium compounds;
    chlorothalonil;
    dichlofhiam'd;
    4,5-dich3oro~2-n-octyl-4-isothiazoline-3-one;
    methylene bis-thiocyanate;

    Just taking one of these (details summarized from Wikipedia)- Chlorothalonil is a broad spectrum, non-systemic fungicide. It is a Category I "severe" eye irritant. It is not considered to be acutely toxic by ingestion but is toxic when inhaled. In animal tests, long term chlorothalonil exposure resulted in kidney damage. It is highly toxic to fish and aquatic Invertebrates, but not toxic to birds. The main breakdown product of chlorothalonil is 4-hydroxy-2,5,6-trichloroisophthalonitrile. It has been shown to be 30 times more acutley toxic than chlorothalonil and more persistent in the environment.

    Apparently 12 million pounds are used annually in agriculture in the US, but I think not in my vegetable garden thank you very much.

    Ralph
     
  18. bob 2

    bob 2 Active Member

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    Hi Ralph:
    I dont mean to get a debate started about the viability of this preservative but I think we should discuss just what the measure of toxicity is in terms people can understand.

    For chlorothalonil the oral LD50 is greater than 10,000 mg/kg in rats and 6000 mg/kg in mice.
    This equates to 10 grams per kilo.
    For us oldies that about 1/3/of an ounce.
    That amount of this substance will kill half of the test rats.

    If the toxicity remains the same in humans then average an 160 lb human( 72 kg) would need to ingest 720 grams of chlorothalonil ingested at one time to have the same effect.
    If memory serves me thats roughly 1-1/2 lbs .

    I would think we must be talking ranges of chemistry far lower than these criteria available on the surface of treated lumber?

    Bob
     
  19. cowboy

    cowboy Active Member

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    As someone said, "The poison is in the dose." What about aspirin?

    Material Safety Data Sheet

    Acetylsalicylic Acid 99%

    Oral, mouse: LD50 = 250 mg/kg;
    Oral, rabbit: LD50 = 1,010 mg/kg;
    Oral, rat: LD50 = 200 mg/kg;


    This is obviously a more toxic substance than Chlorothalonil, yet we ingest it in the name of health. Ralph, please stop trying to scare us with long chemical names. There is too much scare mongering in our society in an attempt to increase product sales and effect philosophical conversions.

    We will all die at some point in the future and some of us after a lingering and painful illness. It seems to me that there is an implicit belief that by eating "organic," the inevitable demise will be posponed and that any pain will be ameliorated. In the absence of any scientific research showing this to be true, such a belief is only a philosopical, religious belief.
     
  20. Millet

    Millet Well-Known Member 10 Years

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    Forget about all this fatuity of how toxic, or how non-toxic, these substitute suggestions are, and JUST SIMPLY USE cedar or redwood. So what if it rots in ten years, as Soccerdad injects, that's not a big deal. After ten years, take an afternoon and repair it. We are not talking about building a bomb shelter or residence. It's just an every day simple raised bed !!! - Millet (1,434-)
     
    Last edited: Feb 15, 2009
  21. Warrior 101

    Warrior 101 Member

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    Now this is very useful. At our new home, given the space limitations (wife does want some lawn!) I was thinking of growing some veggies in a raised bed beside our parking pad and using pressure treated timbers (I guess my choice of timbers tells I was not "thinking" lol).
    I can't picture at the moment putting the money out for cedar, but this formula on spruce just might do the trick Thank you
     
  22. Yubalover

    Yubalover Member

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    Is there anyone in northern California???
     
  23. bob 2

    bob 2 Active Member

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    I'm replacing my 5"x5" landscape ties that I have used for about 10 years.
    They have rotted through in some spots and not others.
    I am going to go with them again.
    I built them 3 high last time. I think this time I will put landscape cloth around the interior just to help prevent weeds from visiting from the lawn.
    They should cost me about $75.00 each ( 5' x 5') plus rebar to lock them in place.
    That's about $7.50 per year.

    I forgot to mention that anything that lasts 10 + years in a garden setting dosen't really need additional preservatives. You will replace thes ties probably fewer times than your car or bicycle.

    I'm o.k. with that.
    Bob
     
    Last edited: Apr 27, 2009
  24. orgcol

    orgcol Member

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    Yes and asprin is poisonous even at low doses over a long period. I know that because I have suffered the consequences of taking the 'perfectly safe dose'.

    The question of organics is complex but I believe that if you constantly eat poison, even at the low doses of pesticide residues, they WILL have an effect on health. New studies are coming out to show that even at residue levels pesticides can increase the chance of getting diseases like Parkinson's. Personally I do not want low dose poisons in my food so choose organic food and never use treated timber in the food garden.
     
  25. bob 2

    bob 2 Active Member

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    It's nice to live in a world where each person can make descisions based on their current knowledge.

    Bob
     
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