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Raised beds, is it ok to use treated timber?

Hi I purchase some wood last autumn treated with Tanalith E and made a raised bed .I was then told this wood treatment wasn't very safe to use when growing vegetables because the chemicals could leech out :( .

The raised bed has been outside all winter so hopefully it will have had chance to weather a bit and any chemicals will have reduced a little. I have yet to fill it with soil and compost, it is only half full at the moment so it will have some fresh compost in it .

I still need to install another small raised bed and have a bit of wood left over , do I play it safe and buy plastic this time or is it ok to use the Tanalised wood?

Opinions appreciated..

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Super Green Thumb
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Location: Central Sand Hills South Carolina

I have read that the treatment process uses much less harsh chemicals than was the case several years ago. So treated wood continues to be my material of choice for constructing raised beds. Just to be on the safe side, the beds are lined almost to the top, with 3.5 mil plastic sheeting, to help prevent the soil from coming in direct contact with the frame. A few drainage holes are punched in the bottom of the plastic liner. Walmart carries 10 x 25 foot 3.5 mil sheet plastic for about $10. IMO this arrangement limits any kind of leaching into the soil to a bare minimum, such that very little of anything would likely make it all the way into any produce grown in the beds.

Another alternative that I've considered is to line the beds with concrete board. The material is very inexpensive, and could be applied in such a way that would seal most anything from migrating through to the planting medium.

Charlie MV
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if you were in the US I'd suggest a wood like cypress. I know English white oak was used for ship building in the UK and it might be affordable. May be worth a call to a few lumber yards for local suggestions.

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Green Thumb
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I also used treated lumber for my raised bed but as Alex has stated I lined it with plastic just in case. He is also correct stating that the chemicals are not near what they wear a number a years ago. When I did my research on it I found that there were a number of studies done showing a very small trace with in an inch of the lumber in the dirt and in growing a number of different vegetables there were no trace of any chemicals that were used in the boards in the plants.

Also if they are weathered already I would think the chances would go down dramatically since all the treated moister has been sucked out of it already.

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Thank you for the replies everyone :D

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if your growing food in a raised bed, pls try out a product called eco wood treatment,its all non toxic , and the boards wont rot it may be at the sherwin williams store thanks

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Super Green Thumb
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Yes it works fine I have 3 raised beds made with deck lumber 5/4 x 6 x 8. Pressure treated is guaranteed to last 20 years and they do.

I have tried wood that is not pressure treated 2 years and it needs to be replaced.

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Green Thumb
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To each, his own... but, I just can't do it (use chemically treated wood for garden beds).
I grow my garden organically, taking every effort to eliminate chemicals and chemical residues. To me, using treated wood would be a step backwards.

Cedar or Cypress woods will last a long time.

Wood can be replaced; your health can't !

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I prefer cedar, but will still use pressure treated.

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I just purchased the lumber for my raised beds and they assured me that I didn't want treated lumber. I bought spruce which will last awhile (not as long as cedar) especially since I plan to line the inside walls with plastic and paint the outside. I am also placing it on 4" high cement blocks to prevent rot on the bottom.

I am interested in the eco wood treatment and will check around this weekend.

We had built a raised bed many years ago (1990s) with landscape timbers and then learned about the leaching of chemicals. We turned it into a flower bed. It's been about 12-14 years and it is time to take it out due to rot.

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I use regular 2 x 12 lumber. I get a 10 foot piece for $9. It takes 3 to make a raised bed that is 5' x 10'. For $27 I think it is worth it and you don't have to worry about chemicals. These last me at least 3 years. Granted the insides of the boards get rotted etc., but not the outside. I just pulled some 3 year old wood out and I could have left it. In fact, it was hard to get the screws out in the corners. The only reason I switched it out is because I was converting some smaller 4 x 4 beds to one large one. I have built for garden over several years so I don't have to replace wood all at once either.

I only use treated wood for a couple of beds where I grow flowers to attract beneficials insects. Personally, I don't think the treated lumber with the chemicals is worth the risk. My vegetable garden is 100% organic so it wouldn't make sense to use the treated wood.

In my area, the cedar etc. is like $30 for a 1 x 10. I've got around 800 square feet of raised beds so that would get pricey.

I would add an option that I am going to experiment with. The cedar fencing that is 1 x 6 x 8 feet is only $3.50 a board. You could get crafty with that and make something pretty cool looking for about $30 that could be 6 x 8 feet and 12 inches deep with 9 boards. Although I would probably only go 5 feet wide because 6 feet gets hard to reach. The extra foot you cut of each board you can use to brace the corners, etc.


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You know, I'm sure that there's a scientific study somewhere that says using modern treated lumber for a garden bed is totally fine.

However, I just don't like the idea of it. So I guess it's largely personal preference. I personally prefer not to use it :wink:.

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