- Editors Corner
- Dear Dr Tomato
- News & Events
- Newmarket Farmers Market
- The Dr Tomato Road Show:
Editors Corner
Dear Dr Tomato
Well, I am happy to report that I am feeling MUCH better! Thanks to all of you who sent me wishes for a speedy recovery. As I told you last week in my highly abbreviated newsletter, I will try to answer a question that I AM asked all the time by new and well seasoned gardeners. CAN I USE PRESSURE TREATED LUMBER TO BUILD MY RAISED BEDS?
As always, I will not answer this with a simple yes or no. Instead, let’s go back in time a bit to the 1980’s and 1990’s. For builders and gardeners alike, a common problem was keeping wood from rotting. Technology had basically offered three solutions to “solve” the problem of wood rot. The first was CREOSOTE – that sticky, smelly, black resinous goo that we all associate with railroad ties and telephone poles. Made of a multitude of organic compounds, coal tar and petroleum derivatives, creosote made its way into our gardens as we began to build raised beds using reclaimed railroad ties. The second “solution” was a preservative treatment using PENTACHLOROPHENOL. But this chemical is in the same family as 2,4,5T and contains such comforting compounds as dioxins. The third option was a “new” preservative class called CHROMATED COPPER ARSENATE – or CCA wood. This is what we began to fondly call PRESSURE TREATED WOOD.
Wood to be treated was placed in a chamber and soaked with CCA. CCA contained copper, arsenic and chromium compounds dissolved in ammonia. All the air was then pumped out of the chamber to create a vacuum which drew the CCA deep into the wood.
I know what you are thinking – ARSENIC! BUT, as usual, you need to consider a few things. First, we ingest arsenic everyday in our food and water – in very small quantities. Second, there are 2 forms of arsenic. The first is ORGANIC – which roughly translates to arsenic being bound to a carbon containing compound. The second is INORGANIC – which roughly translates to arsenic being bound to compounds containing oxygen, chlorine or sulfur. Organic arsenic generally does not accumulate in the body and is excreted harmlessly. Inorganic arsenic, on the other hand, accumulates in the tissues and cells of the body and is not excreted. Over periods of exposure to increased levels of inorganic arsenic, the body can begin to show signs of arsenic toxicity. These signs and symptoms can range from vomiting and diarrhea to nerve damage, blood vessel damage, heart rhythm abnormalities and cancer. Chromium can also become toxic and is a suspected carcinogen.
Just to give you a reference, a 2”x6”x12’ CCA treated plank can contain about 1 ounce of arsenic (inorganic). A telephone pole can contain up to 40 pounds of arsenic. Burning scraps of CCA lumber can release unsafe amounts of arsenic into the air and the ash is considered hazardous waste.
Are you cringing yet? Well, on the other hand, tests done on CCA lumber showed that there was a minimal amount of leaching into the soil and whatever leaching occurred only traveled inches from the lumber. Further tests indicated that certain plants could take up some of the arsenic but the amounts were again too small to cause concern.
In 2002-2003 the industry, under some pressure, decided to discontinue the use of CCA lumber. There was actually more concern for the amounts of arsenic that could be transferred to children’s hands from touching the CCA lumber and then putting their hands in their mouth. There is little debate that the move to discontinue CCA lumber production was a positive one.
Any “treated” lumber you buy today does not contain either arsenic or chromium. The new treated lumbers fall into a couple of different classes. You will see labels and flyers describing lumbers such as:
CC lumber or Ammoniacal Copper Citrate. This is a treatment of copper oxide plus copper citrate in an ammonia base.
CBA lumber or Copper Azole. This treatment is a combination of copper, boric acid and tebuconazole which is used in commercial fungicides.
ACQ lumber. This is probably the most widely used formulation on the market today. This group uses a treatment made up of alkaline copper and quaternary ammonium (nickname QUAT). ACQ lumber contains no arsenic, chromium or other compounds classified by the EPA as “hazardous preservatives”. QUAT is a compound used in commercial disinfectants and cleaners.
ACQ lumber also comes in a couple of different forms. The first is ACQ-B which uses copper in the form of ammoniacal copper. The second form is ACQ-D, which uses copper in the form of amine copper. One thing the D form does is give added water repellent properties.
So, we all run out and buy ACQ lumber to make our raised beds – right?!? Well, the EPA does “approve” it for use in gardens. But, (there is always a BUT), ACQ also leeches small amounts of chemicals – primarily copper compounds. If you are an ORGANIC grower, the National Organic Program is VERY clear on the use of treated lumber. In their regulations, section 205.206 states:
“The producer must not use lumber treated with arsenate or other prohibited materials for new installations or replacement purposes in contact with soil or livestock.”
Their regulations go on to state that “other prohibited materials” include copper azole wood (CBA) and alkaline copper quaternary (ACQ). Treated wood can be used for things such as fence posts and buildings but CAN NOT be used for:
* Plant stakes
* Trellises
* Raised beds
* Livestock feeders or watering containers
* Walls, floors or shelves where organic product will be stored,unless the product is in impermeable containers
* Livestock enclosures where the stock could chew on the lumber
So what do we do? First, only you can make the decision as to whether you choose to use ACQ wood for your raised beds. Here at Healthy Home Harvest, we build our beds out of stone, masonry blocks, untreated lumber or rot resistant woods like Cedar. In fact, we now make a 4 foot by 8 foot raised bed garden kit for sale and use premium cedar. This should give an average life expectancy of around 10 years. Cement blocks are fast, quite inexpensive but don’t give a very “elegant” look. Stone is my material of choice for looks (and long life!) but can be pricey if you have to buy them and hard to move. “Plastic” lumber made out of recycled materials? Can be a good choice. You do have to check what the “wood” is made out of since some manufacturers make it out of HDPE (high density polyethylene – remember that from the article about greenhouse plastic condensation dripping onto your plants?) which is good and some may use a mix of all kinds of recycled materials including ground up tires which can leech chemicals. “Plastic” lumber does have aesthetic issues, is somewhat difficult to work with and can have issues with expansion and contraction as the temperature changes dramatically.
As usual, my goal is not to dictate to you what your decision should be. Rather, I strive to give you a level of knowledge that may help you make the decision that best suits your needs and growing philosophy. Get in touch with me if you have any further questions on this subject. Get those gardens ready!
Until Next Time,
The Healthy Home Harvest team
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News & Events
Newmarket Farmers Market
When: Saturday, April 21st from 9:00am until 1:00pm.
Where: The Stone Church, Newmarket NH.
This Saturday, the 21st of April, James & Loretta will be at the Newmarket Farmers Market. In addition to having our famous fresh, organic mushrooms and herbs, James will have a full van load of vegetable and flower seedlings, Rowdy Roots organic potting mix, Dr. Tomato’s fertilizer, low tunnel hoops and all the growing information you need. Come join them!
The venue is small and intimate. The vendors are diverse, enthusiastic and friendly. There is great food available and some very talented live musicians provide first class entertainment. The feeling is more like a family gathering than a trip to the local store. We look forward to seeing you at the next Newmarket Farmers Market!
For those of you not familiar with Newmarket, the Stone Church is up on the hill behind the Post Office in downtown Newmarket. This is our favorite farmers market! Good atmosphere, live music, some wonderful vendors, good food and a variety of products. See you there!
The Dr. Tomato Road Show:
This Saturday, April 17th, Dr. Tomato will be at the Blue Seal store in Windham, Maine for a gardening clinic and question/answer session. Next Wednesday night, April 21st at 6:30 pm, Dr. Tomato will be giving a presentation to the Barrington Bloomers at the Barrington Public Library. This is open to the public and will cover such topics as tomatoes, container growing, low tunnel growing and season extension, diseases, choosing vegetable varieties for your garden and answering any and all questions. Then, on Saturday the 24th of April, Dr. Tomato will be at the Blue Seal store in Rochester, NH from 9:00am until 1:00pm, covering many of the same topic areas as the Barrington presentation.
About the Newsletter
The Healthy Home Harvest newsletter is a bi-weekly publication which consists of news, events, how-to and reader submitted questions.
If you have any questions or feedback, please email us at feedback@healthyhomeharvest.com