I priced 2 x 12 Western red cedar for my 6 raised beds out back and, wow, it is pricey. Using 2 x 6s and joining them saves a bit of money. BUT one established sawyer around here said to use Douglasfir instead–cheaper, and his raised beds have lasted “20 years.” What do you think?
Discussion Forum
Get It All!
UNLIMITED Membership is like taking a master class in woodworking for less than $10 a month.
Start Your Free TrialCategories
Discussion Forum
Digital Plans Library
Member exclusive! – Plans for everyone – from beginners to experts – right at your fingertips.
Highlights
-
Shape Your Skills
when you sign up for our emails
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. -
Shop Talk Live Podcast -
Our favorite articles and videos -
E-Learning Courses from Fine Woodworking
-
-
Replies
Neither will be anywhere near as good as treated wood. Depending on where you are in the country, pressure-treated wood is usually southern yellow pine and is relatively inexpensive. It is one of the only wood products that is rated for ground contact.
If these raised beds are for a vegetable garden, I would not use pressure- treated wood. This may seem overly cautious, but nobody in my circle of gardening relatives or friends would ever consider growing veggies in such a frame.
How nice do these beds need to look? In a newly established community garden here on the island, they used split cedar trees, original diameter probably 6-10", stacked to frame the beds. The trees were of little commercial value, but had to be cleared for buildings. If you live where cedar grows, perhaps you could find a way to salvage some smallish trees like that, for less than cut lumber??
"If these raised beds are for a vegetable garden, I would not use pressure- treated wood. This may seem overly cautious, but nobody in my circle of gardening relatives or friends would ever consider growing veggies in such a frame."
While at first blush this concern makes sense, particularly with older treated wood which used the arsenic copper chromate process, the amount of arsenic and/or copper in the wood was very, very small. Most soils in the US have considerably more of these two minerals as trace elements when the volume of the garden bed vs. the volume of the retaining wall.
However, this is even less of a concern now. New pressure-treated wood uses micro-ban and copper chromate. Micro-ban is in most plastic items now sold as children's toys and kitchen utensils. Considerably greater exposure to copper and chromium than garden vegetables could ever result in is had at the water faucet and our food.
Generally speaking, most minerals like this are toxic in large concentrations, but absolutely essential in small concentrations. Copper and chromium are examples, as is selenium.
I understand about there being extreeeeeemly small concentrations of "this 'n that" in the wood, whatever the treatment is. For some time now, those who are super-conscientious about their food and other exposures to chemicals are taking a broader view -- that of considering the cumulative exposure resulting from all sources, many of which we may not be aware of.
I'm not an organic-food seeker, though I will certainly opt for organic when I can afford it. I'm just not disciplined enough to go all out in that respect, I guess. But I can understand the principles involved and why one must take a broad view if serious about reducing overall risks. Knowing that something is used in plastics for microbe-control gives me no comfort whatsoever, LOL.
Yep, I know about those elements that are needed in minute quantities ("trace elements"). Selenium is an important part of horse nutrition, but it's quite easy to have them get too much -- especially when owners jump on a bandwagon supplement-wise.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
"I understand about there being extreeeeeemly small concentrations of "this 'n that" in the wood, whatever the treatment is. For some time now, those who are super-conscientious about their food and other exposures to chemicals are taking a broader view -- that of considering the cumulative exposure resulting from all sources, many of which we may not be aware of.
I'm not an organic-food seeker, though I will certainly opt for organic when I can afford it. I'm just not disciplined enough to go all out in that respect, I guess. But I can understand the principles involved and why one must take a broad view if serious about reducing overall risks. Knowing that something is used in plastics for microbe-control gives me no comfort whatsoever, LOL."
ForestGirl - The difficulty is that this philosophy is based on a false premise. That is, that not adding anything in the way of "artificial" (or even "natural") ingredients when growing the food results in a product that is more wholesome than it would be otherwise.
Unfortunately, the real world is not so simple. There are many "organic" or "natural" products and foods that are significantly more dangerous than the equivalent product that uses modern methods of production and processing.
I suspect this is a normal human reaction to complexity - there "must" be a simple answer to the toxicity issues of the agricultural chemicals of the 1960s and 70s, and it should be easy to understand the rules, regardless of the person's educational background.
Sadly, however, this view is entirely and irrevocably false, however emotionally disquieting it may be.
"There are many "organic" or "natural" products and foods that are significantly more dangerous than the equivalent product that uses modern methods of production and processing." How does that statement possibly relate to raw vegetables picked from a garden? Makes no sense to me whatsoever. forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
What I mean by that is that home-grown vegetables, depending on the circumstances of their production, can carry significantly more risks than commercially-produced, modern agriculture equivalents.
Much of the "organic foods" movement, that includes home gardening, tends to promote the idea that natural production methods (that do not include the use of pesticides, and depending on whom you ask, does not include the use of inorganically produced fertilizers) carries less risk to the consumer than the alternatives. This is emphatically not the case, and would include the risk assessment of using PT wood, or not, to structure a home garden bed. In other words, simply because a material contains chemicals that are artificially produced does not mean that using it carries risks, and using materials and chemicals that are naturally produced does not mean that it carries less or no risks in comparison to the natural (unadulterated) material.
This, I think, is what John White is getting at - modern PT wood does not carry any danger of contaminating garden vegetables.
"What I mean by that is that home-grown vegetables, depending on the circumstances of their production, can carry significantly more risks than commercially-produced, modern agriculture equivalents."
Please explain.
The produce we get from our garden is far superior to any that I can buy in a supermarket - no question about it, and I don't doubt safer because it's much fresher.
If you are referring to preserving, that's a whole different subject.
Thank you, Polar, for asking that question while I was gone. He still hasn't explained how growing vegetables without pesticides and traditional commercially produced fertilizers can actually harm the eater.
We have a raspberry patch, they grow and spread like weeds here. I've never fertilized them or used any kind of pest management. Am I to assume that I might be eating harmful raspberries because I don't do these things? ROFL!!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Well, again it depends on the details of its production, but here is just one example (there are many more). Many folks that grow their own produce also grow it "organically" and use animal manure as a fertilizer and soil amendment. Both chicken manure and cow manure often contain human pathogens. One of those that's particularly nasty is E. coli H157. Very, very few cells of this bug are necessary to cause a violent reaction in humans that leads to kidney failure, nerve damage, and unfortunately, death.
While the vegetables don't internalize this pathogen, it does exist on the surface of vegetables growing in contaminated gardens. Simply washing the vegetables with tap water is insufficient, and one of the latest studies confirms that processing vegetables and meats contaminated with H157 rapidly contaminates the kitchen environment.
As you might imagine, this sort of contamination is not possible in gardens/fields using chemically-derived fertilizer.
This is not, of course, a reason not to grow your own vegetables. But what I'm pointing out is that simply because you're growing it yourself does not make it superior to what you can get in the store. I do see this statement rather frequently in magazines and in other sources, and unfortunately it's not that simple.
Here is another example - many new housing developments are built on former agricultural fields from the 19th and 20th centuries. In contrast to today's agricultural chemicals, many of the pesticides used in orchards and on vegetable fields from this time period are very long-lasting, and contain arsenic and sometimes mercury as a primary ingredient. Gardens grown in this soil will yield vegetables that are simply unsafe to eat, though one cannot know simply by looking at the vegetable. In this case, the vegetables obtained from the store are far safer to eat than ones you could grow yourself. And this is not a single isolated incident - there have been multiple examples over the last 15 to 20 years.
Finally, realize that it doesn't take specific contamination by man to do cause such problems - there are many areas in the country where the mineral make-up of the soil contains significant and dangerous levels of arsenic, mercury and other heavy metals.
This doesn't include many of the pathogens other than E coli 157 from animal waste used as a fertilizer - there are others as well.
Here is another example - many new housing developments are built on former agricultural fields from the 19th and 20th centuries.
I THINK I understand. No farmer here but I think I understand the outcome.. I have much what I think is some kind of clover growing. I wish it would just cover the entire back yard! The rabbits LOVE IT!
And then again I send seeds of native wild flowers and nothing seems to grow!
Many thanks for the responses--dkellernc estimates Dougfir lasting 10 years, redwood 15 or more, and boilerbay says 15 years for dougfir on the coast (that's me). Thanks, too, to John for posting the link to the gardening site--I was interested to read the site Administrator estimate cedar at 1-10 years, and to read John's distinction between pressure treated and dipped lumber for the garden. I won't be going with my original cedar plan. But I can get Douglas fir 2 x 12 for not much more than dipped garden ties.
"Many thanks for the responses--dkellernc estimates Dougfir lasting 10 years, redwood 15 or more, and boilerbay says 15 years for dougfir on the coast (that's me). Thanks, too, to John for posting the link to the gardening site--I was interested to read the site Administrator estimate cedar at 1-10 years, and to read John's distinction between pressure treated and dipped lumber for the garden. I won't be going with my original cedar plan. But I can get Douglas fir 2 x 12 for not much more than dipped garden ties."
Well - that wasn't me giving the estimates on how long Doug Fir or Redwood will last. I'm on the East Coast, and doug fir or (especially) redwood would be dang near the same thing as using rosewood as garden terracing. I would recommend buying some new PT lumber at the big box store, and if you're concerned about leaching, line the inside with polyethylene sheeting. Not only will that form an impervious barrier no matter what's in the wood, the terracing boards will last considerably longer.
I do not know your background but I wonder were you get your information about E coli h157. If you take fresh manure and spread it on the garden plants yes you may get sick. if you use well aged manure and incorporate into the soil then plant, I can not see you getting ill as hundreds of people would die every year with in 20 miles of me.For some reason you mention the mineral derived fertilizer is better in a commercial situation. well us to a point till you get run off into the water ways, remember the phosphate thing a few years ago. They still occur due to floods, leak is in municpal water systems and subsequent Blue-Green Algae blooms every bit as toxic to humans and animal as h157.Next look at the out breaks from huge commercial farms that use sewage contaminated irrigation water for food production.
http://www.californiaprogressreport.com/2007/03/hiding_the_ball.htmlAlso most h157 are from uncooked meats, poor food handling such as using a knife on raw meat the using it and on an uncooked salad ingredient. not cleaning cutting boards and plain old poor hand washing.Walkerton , Ontario. cattle waste ran into a water treatment plant. The plant operator ignored initial tests and did a bit of jail time for screwing up.Cattle given antibiotics in feed lots encourage antibiotic resistance and therefore letting pathogens mutate.I have had food poisoning 3 times. Two from commercial establishments,one military food.
I have eaten thousands of meals of home grown on the farm fruits and vegetables and beef, pork, and chickens we slaughtered and butchered ourselves. Many gallons of fresh milk and cream. Can't remember me or any of the farmers I know getting ill from there own food.My first day on the job as a RN on an orthopeadic ward, we had 48 h157 folks from a nursing home, due to under cooked beef. None of the staff came down with it and believe me the #### did hit the fan, floors, walls, etc. The smell on the ward was a gagger.As for wood for raised beds Tamarack AKA Hackmatack. It won't rot in your life time and is not toxic as it is used to store potatoes.
As far as know, no-one uses fresh manure on a garden other than possibly spreading it on in the fall and allowing it to age. It's more of a soil conditioner than a fertilizer anyhow.
Commercial farming hasn't been developed to produce the best food, only the most food for the least amount of labor and money. Same with feedlot livestock.
The question about why use raised beds? Where I live the soil is clay and dries slowly, if I waited until the clay was dry enough to work I wouldn't have much of a crop. I can plant much earlier and in much easier to work soil with raised beds. If you have loam, silt or glacial till - lucky you.
Clay also dries very hard, once the fines are washed away. I recall seeing folks layering straw with clay for raised beds. Gradually the straw breaks down and mixed with the clay it helps to keep it from packing.
As an antithesis, I used clay on top of several layers of 2" stone in the driveway a couple years ago. Now it's like a cobble stone driveway and is as hard as concrete. It doesn't wash out any more either, clay mostly sheds water if it can run off. Otherwise it turns mucky.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Bob.. Clay also dries very hard, once the fines are washed away..
What the heck are fines?
No farmer here and I do not use any chemicals. Ok so the dogs sometimes drop stuff on the plants. I tried raised beds at one time. The weeds seem to love them! Maybe the quick warmth from the early morning sun?
This year has been a disaster as far as garden food. I have two small cabbage and a few tomatoes. One thing that always grows well in my back yard are potatoes! Hell, I can throw out a potato on the ground in the fall and the following year I have a few of them. The potato does not even have to be underground?
Will,
What the heck are fines?
Fines are, well fines. It's the very fine powdery particles of sand/dirt/clay. In terms of clay it is really slippery when it gets wet, and makes for a slick driveway, don't ask me how I know this. :-)
I came home one day after it had rained. I had laid down some stone and a layer of clay on top the night before. Wiped out the mailbox trying to turn into the driveway. It felt like I was on wet ice.
After a few rainstorms the fines wash away and/or sink down into the stones, like concrete, just takes a little time.
Yup, or taters got late blight and lost every plant. The taters were like tater tots. The tomatoes however, in the greenhouse, were great. I'm making pasta sauce for this winter, almost as I type.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Selenium poisoning is quite common from soils of some of the western states. I think it is an economic factor for raising cattle, sheep and horses. These soils are virgin and have never had any applied amendments. Am not sure how the new treatment method works but I have noticed from a treated trellis that it takes a while for the chemical to wash off before some plants will grow in the area. Some one mentioned cedar. I have some cedar posts that have been in the ground for almost one hundred years and they are still solid.
Edited 10/15/2009 10:31 pm ET by Tinkerer3
I won't comment on PT wood other than to say I wouldn't personally use it. I can say with some degree of certainty, that unless you live in the desert you'll be lucky to get 10 years out of doug fir. I built mine from con-heart redwood that was available some years ago at Conde's redwood lumber near Coburg, it's been about 15 years, and some of it has deteriorated.
If you need to build them out of fir I suggest using 1x material and use rebar to hold it in place. It'll be a lot cheaper and last just as long. Depending on where you live you may be able to get offgrade rough white oak cheaply and it would hold up pretty well.
**Unless you are disabled and unable to stoop, 6-8" is sufficient. 12" does look better but.........$$$
Edited 10/10/2009 1:49 am by polarsea1
Modern pressure treated is a very different product from the PT of 30 years ago and is considered to be very safe for use in creating garden beds, for that matter the old stuff was probably safe but since it isn't available its safety is a moot point.This site has a rational discussion on the subject: http://www.gardeningblog.net/2009/04/12/using-pressure-treated-lumber-in-raised-garden-beds/#comment-30350Read all of the article and the following comments before forming your own opinion.John White
Shop Manager for FWW Magazine, 1998 to 2007
Jim,
Don't know your climate but it's much the same here. I used PT 2" X 12" on one 8 x 4 bed but the new ones will be DF. We are hard into the wood rot area on the coast and still a lot of DF raised beds are 15 or so old. How long do you want that puppy to last anyway? It's only a garden box! :)
BB
And then again you could use STONE blocks that will last forever!
I don't get it. Why raise the beds?
Plants grow perfectly well at ground level. If you prepare the soil in the same way as in the raised bed, the plants will grow the same way.
If you grow at ground level, you don't have to pay for materials to make the raised bed, and you don't have to debate what materials to use. Seems better to me.
My raised beds have been in for about five years now, and if they ever rot I will be replacing them with the new non wood deck "boards", as they should last a lifetime.
Ok - here you go - file this under "No Such Thing as a Free Lunch"
1. John W is correct - there is no danger from current PT Products.
2. There never was any danger from the earlier (CCA) version. It was all emotion and soundbites and contingency-fee lawyers scouring the countryside to assemble a group that they could get the courts to certify as a "class" for a class-action suit.
3. The EPA took the "easy out" to avoid confrontation and avoid making any kind of actual decision in the midst of a political firestorm - it simply declined to renew the approval for CCA. In the cold sober light of dawn - after it was all said and done and nobody was watching - the actual SCIENCE was completed and - VOILA!! The lower-cost, decades-old, bulletproof product you can't get anymore was okey-dokey all along. Oooops. Of course, there was no effective substitute for CCA in agricultural applications (read: pole barns & other structures), marine applications (decks, docks, seawalls), or plywood (other chemicals known at that time did not work with the adhesives). So - the EPA let CCA continue to be used there. Hardy-har-har-har.
4. The EPA's approach was great for the Borgs - that meant they ALL had to move to a new product, and would ALL have the same new (and higher) cost structure - no one would have an advantage/disadvantage in the Sunday supplement advertising.
5. And here's the punch line: No such thing as a free lunch. Use the Doug Fir or the Redwood. 10 year life-span seems right to me (definitely not 20). Then, every 10 years, go cut down another DF/Redwood tree, and replace your bed structure. OR use PT lumber that lasts 50+ years, and save the trees.
Eco-consciousness is a great thing, and I applaud and encourage it in all forms, and it is a front-and-center component of my personal actions. Just don't kid yourselves that the "law of unintended consequences" does not apply to socially- and environmentally-focused activities.
Late Edit: In item #3 above - add "structural wood foundations" to the uses of CCA that the EPA allowed to continue. OMG!! Don't go down in the basement!!! I was right as a 6-year old: "There be monsters."
Edited 10/14/2009 3:47 pm ET by Spotcheck
AmenJohn White
Shop Manager for FWW Magazine, 1998 to 2007
Spotcheck,
Sorry, lost you a bit. CCA is chromium copper arsenic?
jonnieboy
yep - close enough - actually Chromated Copper Arsenic
I use 1" rough-sawn pine for my terraced garden in New England. It lasts about 5 years (little rot, lots of termites), but it's cheap and comes from trees that grow fast so it's not a big deal to replace.
Edited 10/16/2009 12:28 pm ET by PeteBradley
This forum post is now archived. Commenting has been disabled