Desparately seeking solutions to pressure treated wood beds.

I was browsing on Dave's Garden today and came a cross an article on Pressure Treated Wood ( the kind with arsenic) and found it very interesting. I then went out to my raised vegetable garden and checked the label on the wood to see if it contained arsenic. It does.

Groan. The garden is quite large. I was a little worried about the issue when I had it built ( it's three beds about 30 ft. long and 3 ft. wide) but there wasn't much research about that at the time. I did line part of the inside with landscaping fabric which is now starting to fall apart and sealed the rest of the wood inside the beds with some cheaper version of Thompson's water seal. That was about 5 years ago.

It is now full of soil and has been producing wonderful veggies for all that time. We aren't sick, but I understand a safe distance from the edge is 15 inches. If that is the case I can grow exactly 3-30 ft. rows.

On top of everything else, I can't find the article I was reading anymore. It was here on Dave's garden and linked to another article from a county extension agent.

Basically, I would like to find the article again -- if one of you wrote it or knows where it is. Or I would like some advice. Is there anyway to salvage my wonderful, automatically irrigated raised bed garden?

This message was edited Jun 23, 2006 8:21 AM

Hi,

I think it might have been the response that I wrote in another thread that you were talking about because it has the link to the extension article. Here is the link to that thread:

http://davesgarden.com/forums/t/617201/

If it's the wrong one, sorry, it just sounded like what I had responded to someone else. I did a lot of research into the topic myself before building my raised beds.

CMox

Incidentally, in case you are interested, I ended up building my raised beds with construction grade pine, I lined the insides with 6 mil plastic. I know it will eventually rot, but I figure I can replace boards one at a time. The pine was relatively cheap, didn't have arsenic issues, and was available in lots of sizes. Zeppy, another DG person, has a recipe for making an organic treatment for pine with linseed oil, turpentine and something else which I forget offhand (I have the recipe somewhere, it might be parrafin) and you can treat the wood with that to make it more rot-resistant. Anyway, there are options! You might be able to replace boards one at a time or something? I'm not sure, once you replace the boards, how long it takes for the arsenic that might be in the soil to dissipate.

Yes, yours is definitely the post I read. I guess, I will need to replace all of the timbers in my raised beds which now have soil in them. I will definitely use the construction grade pine and line it with 6 mil plastic and treat it with something. The linseed oil mix or some other polyurathane treatment would be very good. I have a farm with a lot of large down trees in Mississippi but the cost of having them made into heartwood timbers and shipped to New Mexico would be outrageous.
Anyhow, I very much enjoyed your post and link and I began to feel rather desperate when I realized the beds which I had constructed were actually toxic!
At the time, no one would say it. The studies just hadn't been done. A friend of mine, a chemist who I decided knew little or nothing about agriculture told me to plant marigolds all around the edges with crops only in the middle. Now I wish I had listened to her.

Well, I think that your having sealed the wood on the inside probably cut down considerably on any arsenic that might have leached out, so that was a good idea. The marigolds probably would have helped in hindsight, but since you're not sick, and you've had great veggies, I would not worry too much. I think it's worst for root crops, like potatoes, carrots, etc, that are right in the soil. I'm not so sure that it translocates up into tomatoes and such very easily.

Another thought, in case you want another idea, is this thing from Lee Valley Tools for making the raised bed with pavers. See this link:
http://www.leevalley.com/garden/page.aspx?c=2&p=47455&cat=2
I considered this option quite strongly but was concerned about the winter freeze/thaw cycles with those pavers. Iowa is more of a concern for that than New Mexico. It's a different look to the wood so it depends what you're going for.

I think people didn't think much about the arsenic until recently. I have read about kids playground equipment made with that treated lumber and how all these sandbox type areas were contaminated with arsenic and kids were playing in it all this time. Now they are replacing a lot of those play structures too. I think people have had raised veggie beds made from the stuff for years without becoming ill. It's just a better-safe-than-sorry situation, in my opinion. I still used the newer ACQ treated stuff for edging perennial beds - but I didn't want to use it for the veg beds.

I think I will be uncomfortable with my arsenic treated wood until I do something. I am thinking about having them replaced -- perhaps in the fall, with pine which I first coat with polyurathane to keep it from rotting too soon. I will look into those pavers. They might work fine here. It doesn't matter what it looks like. It is beyond my wall on a vacant lot but not easily visable to neighbors unless they really look hard.

Just a thought.
I don't use wood in my raised beds because they rot so quickly here in the PNW. cinder blocks are relatively cheap, solid and look nice too! I grow herbs in the little hollows of each stone to compliment my vegi garden. It cost about $20 to put in a 4x6 foot bed.

You have a good point there about the cinderblocks. I guess I could put a board over the top to keep them from being so abrasive. That wouldn't add much to the $20, really. I do understand that the cinderblocks contribute to the alkalinity of the soil, though, which is a problem here in the SouthWest. The wood doesn't rot, but I don't think I want to eat arsenic etc!

The central portion of a garden I took over last year was ringed with rotting railroad ties. I removed the last of them this year and also removed the soil to a point about 2 feet from them (arbitrary,I know.) The soil was used elsewhere in non-food-producing areas. The beds are all double-dug with mounded edges and no need for solid sides. An adequate amount of organic matter seems to stablilize the soil against hard rains.

Wayne

Here's a link to an article I found (written in 2003) that suggests you have little or nothing to worry about regarding arsenic treated wood. Hope this is is helpful and correct.

http://www.oznet.ksu.edu/news/sty/2003/treated_lumber011503.htm

Thanks to michael_angelo!
I appreciate that article because I have been eating wonderful veggies from these beds for about 5 years. I do think I will replace the lining this fall, though, just to be on the safe side. The beds have been wonderful. Everything I plant seems happy there.

The article represents one side of the debate only. But I'm sure lining will make things much safer.

Zeppy,
I believe CMoxon said that you hand an organic method of treating wood -- linseed oil and some other stuff. Do you still like that recipe and if so, would you give it to me? I think I will try the plastic liner in the fall. The beds are fully planted in the fall. They have coatings -- landscape fabric on some and water sealent on others. The landscape fabric is beginning to shred in place. Water seal doesn't last that long, as I recall from when I had it on the exterior of my house.

Here is the chief article that got me worried.

http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-June0101.html#as

At the time I built these beds, there wasn't much available on the subject. I live in a scientific community and most of the scientists didn't think it was a big deal. But more recent research is of concern to me. Others are less worrisome, but who knows what will be found when my husband and I have eaten from these beds for 10 or 15 years?

Betty

i know it won't help anyone else, but when i need grow bed sides i usually use black locust lumber, i have eastern cedar but that's normally saved for nicer things. however i may use some cedar in future as i have plenty. it all comes right from the woods by way of chain saw, tractor, and a small sawmill I've run for the last 17 yrs. I quit running the mill for income, just selling logs till i can get enough veggies growing to sell instead.

rubenT:
How lucky for you to have such good wood available to you without harmful chemicals! I have a farm in Mississippi with lots of pine and some hardwoods, many of which fell in Hurricaine Katrina. But I don't have a sawmill and my veggie beds are in New Mexico. I wish you luck using your lovely timber to make raised beds and making money with the veggies you grow there. Here in New Mexico there is a good market for such veggies. Lots of people have come to understand that they need to eat more veggies and that they would just as soon skip the pesticides if at all possible.
As far as I can tell, here in New Mexico, to be completely safe, I will have to line my raised beds with plastic. It could be worse.
Betty

Of course it could! Your liners should work well.

The recipe I have for wood probably isn't nearly as effective as pressure treated stuff. So far it's holding up fine but it's only been a year and a half. I heat paraffin, mix w/ linseed oil, and add to a lot of turpentine. Then I paint two coats. It smells gorgeous. I use pine.

I think I'd recommend re-sealing the treated wood directly with something like polyurethane rather than simply replacing the liner... it does not seem to me like landscape fabric or the like would prevent anything from leaching out of the wood. Studies on the arsenic-treated wood did vary in their findings, but I believe all of them agreed that the problem is only with *unsealed* wood.

hey sorry to hear about your problem, it would always be in the back of my mind when i was eating my food i harvest from my garden. I work in the construction business and a couple of years ago when we were building a hospital i salvaged 12" steel studs , welded them together with a wire feed, put fabric down, and put in really good soil, and i had a almost weed free garden. I run a hula hoe around the plants and it looks like i spend hours weeding. the steel studs keep the dirt warm in the fall and early spring. i bet if you went to a big commercial site you could salvage alot of studs. they even come in 1.5" studs that i built a greenhouse out of with tufftex outter core.hope the helps. craig in montana.

What a beautiful garden! Believe me. Believe me. mine is going to get a heavy plastic lining this fall and in the spring. The chemicals do worry me.

Great idea 888111 - a very resourceful way to recycle building materials! How heavy are those 12" steel studs? It makes me think of those steel I-beams that I see in the construction of new homes around here, but I think it would take a small army to lift one. Must be a bit different to what you are using. Looks great!