View Full Version : Raised beds-pressured treated wood

02-20-2009, 06:31 AM
Can I use pressured treated wood for raised beds? (No animals allowed in the raised bed) Just plants in the raised beds. Please can I have the answer quick please! Thanks!

02-20-2009, 10:08 AM
You are going to get vehement answers to this - both yes and no. So don't count on a quick and easy answer and certainly not a concensus. You will have to do the homework/read on it and make up your own mind.

I personally have determined that I am comfortable using pressure treated timbers in my garden. The current chemical used to pressure treat the wood has been through the safety testing regime and is considered safe to use around food producing plants. Would I prefer to use untreated wood? Yes, of course. And I do have some beds made with untreated lumber but sadly here in the damp Cascadia pacific northwest - it lasts about 4 years before rotting to pieces. The costs and environmental impact of constantly replacing bed edging is greater than the minimal amount of uncertainty I have in using pressure treated lumber that will last 15 or more years.

02-20-2009, 10:18 AM
So I guess I'll use pressure treated lumber because it's pretty annoying making another raised bed every 4 years! Thanks!

02-20-2009, 10:19 AM
Another option is to use untreated wood, but paint it first. I would use a water-based poly, and make sure you really let it dry before exposing it to the elements. This should last longer than unpainted untreated, but maybe not as long as pressure treated.

02-20-2009, 10:23 AM
About how long will it last?

02-20-2009, 11:26 AM
In climates like the PNW of the U.S. and wet areas of the U.K. it is an unfortunate necessity. As you say, replacing wood every couple of years is not feasible.

I take minimal comfort in the fact they have changed the treatment to something potentially less dangerous.

So, as heated as the argument gets, I believe it is a function of the climate you live in.

My guess is my pressure treated beds will last 10 plus years. Untreated stained wood maybe half that. So, unless you want to go expensive cedar or a composit product like Trex, pressure treated may be the best option.

Good luck with the decision. Make it and then enjoy the fun of building, planting and tending your garden!

02-20-2009, 12:11 PM
The study I read said that the leaching into the soil wasn't the big issue since it only affected about 1/2 inch around. The problem was the lumber leached stuff on the surface and children picked it up when they touch it. The new products don't use arsenic. They use copper. Linseed oil is an organic way to seal the wood so you could use pressure treated and seal it with linseed oil. Just cut the wood to size, paint it unassembled, assemble it and spot treat the screw areas.

Now if you have termite problems, you could use cinderblocks, or brick or something like that.

Backyard Permaculture
02-20-2009, 03:11 PM
check the safety data sheet that by law, sellers of any chemically treated lumber have to provide to buyers that request them (at least in the US). Like as not, there are all kinds of warnings and dangers listed, requireing you to wear a mask such as when spraying pesticides, not to burn the scraps, and great care to dispose of any sawdust and waste pieces acording to local laws pertaining to hazardous waste.

As for me, while not seeking for the present Organic Certification for any produce I hope to sell from my struggling Market Garden, the spirit of the law is more important than just the letter of the law.

I would not use pesticides on the plants or soil, why would I use them in the wood to hold the plants or soil. Although shebear stated that the chemicals leached only 1/2" into the soil, that 1/2" is well within reach of the plants in a raised bed, and the 1/2" is vertical, parallel to the plants roots. They have plenty of access to the chemicals.

Other than the extra expense of buying rot/insect resistant woods such as cedar or redwood, if the wood you choose is the common building grade lumber known as fir 2xwhatever, you could always opt to line the inside of the raised bed frame with plastic, such as you might use when mulching a garden with plastic sheeting to reduce the woods exposure to moistur. Or you could use a "SACRIFICIAL" layer of scrap plywood to take the brunt of the exposure to moisture & decay.

In Elliot Coleman's books on Market Gardening and "Four Season's Harvest", he recomends not using even the so called " Safer Pressure Treated Lumber" and use sacrificial wood as I describe above.

Hope this isn't too controvercial


02-20-2009, 03:30 PM
I have to agree with Ron. We are exposed to so many chemicals in the foods we eat. My little garden is one way I can assure that I am cutting my exposure to so many chemicals. As an RN who sees more and more strains of viruses resistant to antibiotics, I believe that the antiobiotics given so freely to many of the animals we eat has caused many of the problems. Then there are the hormones....have you noticed how much younger girls are maturing than when we were kids? But I guess I will stop because I don't really want to get into all that......Kim

02-20-2009, 03:42 PM
Thank you everyone for the advice! I'm going to buy pressured treated but I am going to look carefully at the packaging or the labels. Thanks again!

02-20-2009, 05:21 PM
Sometimes you can get cinder blocks quite cheaply. They work great for raised beds, too.

03-21-2009, 08:02 PM
rocks, bricks, cinder blocks are all good alternatives to wood.

I live in an area where there is a lot of rock and I am hoping to slowly replace my beds with stacked rocks. Its labor intensive and a lot slower than putting some boards together with screws, but in the long run, I'll have a beautiful rock veg garden when I am old...uh, older.

03-21-2009, 09:36 PM
I used pressure treated lumber. Down here in florida's heat and humidity ,It's basically a no brainer .Kiln dried lumber just doesn't hold up outdoors here. The amount of copper that could leach from these boards is so miniscule it almost isn't worth worrying about . And if it was released in large enough amounts to pose a problem it would be readily apparent in the plants . Copper is one of the most effective herbicides known. I used hurricane salvage, that I pulled out of the bay over the last several years. After three recent storms I salvaged several thousand boardfeet of PT 2x dock boards.(assorted 2x6, 2x8, 2x10's) , Good luck, Kevin

03-22-2009, 07:37 PM
I used treated wood I did have some reservations after reading about chemicals seeping into the soil but the guys at the timber yard insisted that it was treated with safe stuff so I decided to give it a chance as others have said with the uk climate untreated doesnt last very long and the plastic alternatives make it very expensive

03-22-2009, 10:16 PM
I'm with Cynthia. As time goes by I want to replace rotted beds with rock. I live in Roxbury, Ma where there is no shortage of pudding stone.