Does anyone know if it is safe to use pressure treated landscape timber to frame in a vegetable garden? I couldn't find much info by Googling it.

Asl long as you are ok eating whatever the timbers are treated with you should be all right.  Whatever is in that wood is going to seep into your soil and concentrate in whatever you plant there.

I have heard its best to stay away from treated lumber. If its all you can find, you should line the inside with some sheeting to provide a barrier between your soil and the wood. Try search for info on square foot gardening. I have seen this issue addressed on various sites/videos.

just No

Arsenic is use in preserving some landscape timbers. EPA has ruled as of March 31,2003 treated wood products for residential use can not contain arsenic or chromium compounds. Ruling applies to ACA, ACZA, and CCA treated woods.
 Copper naphthenate, creosote, and penta are typically used on utility poles, cross arms, railroad ties, post, and timbers.Creosote and penta preserved woods should not be used for playground equiptment. Creosote is a distillate of coal tar. Just sayin.

I'll take the other side of the argument.  I don't worry about it.

The University of Missouri says:


Fine Gardening magazine also has a good article about it here.



I personally think this was an over-hyped risk, at least as it applies to using pressure-treated lumber for garden beds.  I do agree that building playground equipment out of it was a bad idea, since that wood comes directly in contact with children's hands and bodies, but I suspect even that risk was negligible after the first couple of rains and a bit of weathering.

There have been a lot of raised beds built from pressure-treated lumber over the last thirty years or so, and so far I haven't found a single documented case of anybody suffering ill effects from a CCA raised bed.  There are cases of arsenic poisoning in people who were burning it for firewood, or otherwise coming in direct contact with it for extended periods, but that's a different story.  And again, this was with CCA lumber, which hasn't even been available since 2003.

It's a personal health and safety issue that everyone will have to answer for themselves based on their own investigation and conclusions, though.  I'm not trying to convince you, just offering up a contrasting viewpoint.

When I put my 'garden' in using pressure treated, I did quite a bit of research on this topic.  I found some studies claiming the lead/arsenic would leach several (~8 IIRC) inches through the soil in enough concentration to be problematic.  I also found evidence that very little of these pollutants are absorbed in to non-root vegetable plants.  

Some sources recommended replacing the soil along the outer edge of the bed every season.  This is what I do since I always reintroduce some new organic matter to my beds every year.  I also plant at least 4-5 inches away from the edge of all of the beds and don't plant root vegetables.  6 years going and no problems (I get blood work done yearly, lead concentration is on there)... of course, YMMV.

Thanks for the replies.

I wonder how much of the risk (if any) would be eliminated by putting a layer of plastic between the timers and the soil.

I wouldn't use new PT timbers, but if you've got some old ones that you can repurpose, I wouldn't be too worried. If you're really worried, a layer of plastic between the timbers and the soil would help. My veggie bed's made from 10-year-old pressure treated 6x6 timbers. Everything tastes great that I've grown in there.

You just have to figure out for yourself if it is worth it, assess for yourself if you are ok with eating whatever kind of chemical is in the lumber.  Studies can say whatever the manufacturers of pressure treated lumber want them to say and you have to decide if you believe them or not it's just that simple.  Will they make you sick? probably not but might it contribute in some small way to the accumulation of crap in your system that will eventually make you sick I would amost have to certainly say yes.  To me one of the main reasons for planting a home garden is to keep out all the crap that gets in to my food that I don't know about so to add the possible risk of a contaminant that might not even be identified by the manufacturer is just not worth it to me and again you have to figure out if it is worth it to you.

I don't do it. Read the label on the end of a treated board. Still want it in your garden??

If you want raised beds use 8 foot Cedar pickets. Drive wooden stakes into the ground and screw the pickets to the stakes to form a rectangle or what have you. They last about five years are 1/2 the price of landscape timbers and are easy to work with. If you need a taller raised bed use longer stakes and lay the pickets edge to edge. Two pickets used in this manner will make the side of the bed about a foot tall. If you need a bed longer than 8 feet simply scab the boards together.

I won't use treated lumber for my raised beds.  I can't prove there's anything wrong with using treated lumber, but for me its worth the peace of mind to not use it.  I grow my own because I want to know what's in my food, and if I'm using treated lumber that might be leaching chemicals into my soil, I lose that benefit.

The treatment nowdays is just about worthless for protecting wood and in my Biology degreed opinion perfectly save for gardens.  

I long for the preban PT lumber

Ussaully it's High levels of Arsenic and Copper.

Your choice. I would not even contemplate it.

They lowered the Arsenic, but uppped the Copper big time. Copper oxidation gives wood the green color.

Not sure what the long term effects of Copper on Human are, but it's damn effective in killing marine growth as it's the primary active componet in anti-foulant paint.

You might want to ask for a refund on that degree.

Ha!  Not quite grasshopper.  Humans have a minimum daily requirement of copper and so do plants. Soil levels need to be at around 50 ppm minimum for proper photosyntesis.

You have copper water pipes in your house?

They haven't even used arsenic since 2003.  

I used this data to make my decision:  I used pressure treated and worry about it not one whit.

Good luck.

This. Did my own research several months ago and many universities have done similar testing. I believe it was the U of South or North Dakota I read up on. They used both treated and creosote lumber and the leaching into the soil was minimal.

In fact, they found more arsenic in some soil testing NATURALLY then what was leeched into the surrounding soil by the treated lumber. This was done before they removed it from treated lumber.

Also, they found that there was no increase in any of these chemicals found in the fruit of any plants tested. The conclusion was, even if the plants absorbed any of the leeched chemicals from the surrounding soil, they were contained within parts of the plant other than the fruit.



Use treated lumber or even creosote lumber to your hearts content. Myth Buster Arfcom Division has BUSTED this myth.

Yo can get studies that say anything you want them to and I guess believe what you want....

I'm glad someone said it.  They don't use arsenic anymore haven't since 2003.  I still don't use the pressure treated lumber but that is just a personal choice.  Their have been a lot of studies that say plants don't transfer any of the poisons to their fruits any how. most don't even absorb them to begin with.

And I supposed next you are going to tell me that generations have lied to their children about the Easter Bunny?

I've worked "in the industry" selling PT (and other building materials) since 1997. Aresenic was not discontinued in 2003, CCA was.  Chromated Copper Aresenate was discontinued for many products (anything in 2x, 1x, 5/4 4x4 or 6x6 in a .25 or .40 retention level for above ground or ground contact).  Timbers and other products (including all the above) can be made, bought and sold via special order - just not stocked on the shelves.  Many brands of below-grade or marine lumber are still using CCA in a .60 or higher retention levels to prevent failure underground (it works well, the new stuff doesn't).  

What's in use now? ACQ (Alkaline Copper Quarternary), Borates (Disodium Octaborate Tetrahydrate),  & Copper Azole (Copper Boron Azole).  What's different?  Less arsenic, but more of other toxic chemicals.  Did you know that you need special joist hangers and fasteners when using these newer chemicals?  The industry has changed so almost all products out there will work now, but when the change first happened you had to stop using aluminum flashings, stop using electro-galvanized or standard coated fasteners, and switch to copper flashing, or double hot-dipped galvanized flashing, and either use specialty hangers or stainless steel hangers.  Why?  The new treated would eat through the old galvanized or coated fasteners in months, causing failure and rusting out joist hangers.

Now, hangers come in the correct form as a standard (z-max is Simpson strong tie's version) so you don't need to worry.  Contractors use galvanized or copper flashings, and double hot dipped galvanized nails, bolts, nuts, washers, and screws (safe for ACQ) or speciality coated screws (fastenmaster, Primeguard plus, no co rode, etc) or stainless steel hardware to prevent premature corrosion and failure caused by exposure to the chemicals in the new treated wood (ACQ and CBA specifically).  Borates doesn't eat metal, and for that reason gets used mostly for sill plates on concrete since hardened anchor bolts are not galvanized before being inserted in the anchoring cement.

Sounds like stuff I want to eat, for sure.  You still aren't supposed to burn it, inhale the sawdust, or get it in your eyes, or use the grounds for mulch, or let it come into direct contact with food or leach into drinking water.

The EPA and the manufacturers of the products in question all say it's safe for raised beds, children's playgrounds, and picnic tables.  

It's "safe", but if you can avoid it, I recommend using something else for gardens.

Never had an issue in 20+ years of using them.   I like decking 2x6's better though for boxes, much easier to build with...

I use cedar

I wish I would have seen this thread a month ago.  I had cross arms (4x4 cedar wood used on telephone poles) as the border for my raised beds.  These have creosote on them to preserve them.  They were about 5-7 years old when I got them so I wasn't concerned at first, then it started worrying me more and more.  First I removed 6" of dirt around them and lined them with plastic last year.  I still wasn't comfortable so I removed all of them last month and just went with plain 2x6's.  

Creosote is not welcome in my garden.

This is not the same as modern pressure treating chemicals.

A co-worker was going to put in raised bed and wanted to get redwood. He husband said No due to the cost.

I told her to do PT and line it with a pond liner, put some holes in the bottom for drainage.

The plants should not come in contact with the wood she should be fine.

Concrete blocks can be found cheap (left over construction) and make a good border for a raised bed. The bonus is that you can plant various things in the holes of the blocks if you face them up.

Forgot to add, I have a blood test done yearly for traces of bad things, mostly lead exposure since I am a firearms instructor.   In the past 8 years, I've had no abnormal readings or amounts of anything in my blood, whether lead or any other chemical.  I've been eating from a pressure treated box, tomatoes in particular, for the past 20 years.   The worry is really overated.  Like others said, line it with plastic if you are real worried about it.