Pressure treated timbers for garden bed?

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bfunk13

Minister of Fire
Sep 11, 2008
765
Wyoming
I bought some 6x6x8' pressure treated landscape timbers for a raised garden bed for the wife.
After some thinking i am wondering if i shouldn't have gone with cedar or something not treated? Is there anything in the timbers that will cause concern for use as a garden bed? Chemicals that may leach into the soil and then into the plants? I know they are no longer treated with arsenic as they used to be. Just need some advice before i start this project. Thanks
 
If you intend to grow any vegetables or herbs in the bed, or think you might want to in future then certainly return them & replace with something untreated (cedar, composite, masonry...). You are right to be concerned with chemicals leaching from the treated wood.
The MicroPro stuff from Menards around HERE is treated with micronized copper & yes it's much less toxic than the old Arsenic-Copper Quaternary stuff, but it is still definitely not what you want to be growing vegetables in.
 
We are putting in some raised garden beds this year. I used rough cedar bought at an Amish Saw Mill. Bought the boards at a reasonable price. I'm not sure if using treated lumber is good or not, however I did not want to worry about it. Plus the Cedar was cheaper than treated. Good luck with your gardens.
 
I did the same with pressure treated lumber, but I have stapled empty pellet bags to the top, inside, and bottom of these boards. Then I filled them with gaden soil. I don't think I am exposed to chemicals leaching out of the wood. My wood won't rot before I do, so it seems a good deal to me.
 
I emailed the manufacturer and they say the new treating process is safe. Although they do recommend a plastic liner between the soil and the wall.
 
I milled some 2x6's out of black locust. They won't last forever, but they'll last long enough.

Make sure you use the right type of plastic. Some types will get really brittle and break down when underground for a while. I would use something spec'd for burial.
 
I've read in a few places that the new PT wood is OK. One article suggested that the copper would kill the plants long before the fruits or veggies would be toxic.
 
I read that too Flatbed.
 
With all the law suits going on these days I doubt the manufacture would give the ok if they weren't sure its safe. That being said i build mine out of plain old pine. My reasoning is the price of cedar or other rot resistant woods are so much higher that I'm not sure the added cost is worth it. I just built 4 raised beds last weekend in under 2 hours. Maybe I'm being short sighted but I'd rather rebuild sooner than shell out a fortune for cedar.
 
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I was going to build a garden bed out of treated wood myself out of some extra pallet wood that was laying around until my friend told me about the possible dangers of using treated pallet wood around edible plants. I did some research on and it kind of turned me off, so I decided to keep to untreated wood. It erodes after a long time, but it doesn't introduce you and whoever else is eating from your garden to possibly harmful chemicals like fromaldehyde, etc. When in doubt, wikipedia it.
 
Just a side note, my pellet bag liners on the raised beds haven't broken down in two years. But if they do, not much to lifting up the frame and adding another layer. It's a free liner! Cut the bag down both sides and leave the bottom seam intact. That gives you a long peice. I also have used them under some walking rows. No weed roots get through.
 
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I would use cedar, but the risk sounds pretty low. If you want to use the PT boards and are concerned, line the entire bed sides with a continuous sheet of heavy plastic. Leave the bottom open for drainage.

After years of using different systems that always rotted after about 5-10years, we settled on cement! No more rot.

http://www.finegardening.com/how-to/articles/are-pressure-treated-woods-safe-in-garden-beds.aspx

IMG_0720web.jpg
 
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