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Raised Garden Beds


Every year I expand my vegetable garden and build more raised beds. You can never grow enough tomatoes! Five years ago I had started with two 4’ x 8’ raised beds that I made from cedar 2x6s and 4x4s. Last season I added three 3’ x 10’ beds and that brought me up to over 230 square feet of planting area.

Making a raised bed is a simple bit of carpentry that anyone should be able to do. The easiest way to buy some 2x12 lumber and screw them together in the shape of a rectangle. You can make them as long as you like but you should limit the width to 3 or 4 feet so you can easily reach in the bed to plant seeds, pull weeds or to harvest crops.

The next question you’re probably asking is what kind of wood do I use to build raised beds. The whole pressure treated vs. non issue is a complicated one. Does pressure treated wood leach chemicals into the soil? Well the answers are yes and maybe.

The old pressure treated lumber (CCA) is preserved with a process that uses arsenic. Obviously you don’t want arsenic anywhere near something you’re going to eat even in the small amounts that might be present in a raised bed vegetable garden. CCA wood isn’t too readily available anymore so you probably don’t have to worry about coming across it. The new improved pressure treated wood (ACQ) replace CCA pressure treated wood a few years ago. The lumber industry says it safer to handle and use but guess what? It eats through normal galvanized screws and fasteners. You have to use stainless steel screws with CCA wood. Hmmm, I’m not an expert with lumber or chemicals but that sounds fishy to me. I think I’ll avoid it until some long term studies are done.

The first four raised beds I built were from cedar. But cedar is really expensive and my wife wanted to kill me for spending $300 on wood that I was going to leave in the yard. My latest raised beds are built from regular non-pressure treated lumber that is rotting away in my garden as we speak. If I get about 5 years of use from it, that’s good enough for me and my veggies.

8 Comments:

  1. Anonymous said...
    dear Compost bin.
    I have been surfing the net for a simple description of haw to make a raised wooden bed and found it on uoour site. Ilkie the site. Having got the information, I browesed and enjoued it very much. Thanks keep up the good work.
    Anthony said...
    Thanks for the kind words Anonymous. I appreciate it.

    Since you liked the raised garden bed post, you may also want to check out one of my more recent posts about Building a Garden Trellis.
    McFloyd said...
    What are the advantages of raised beds in your opinion?

    And ... you're on my feed reader.
    Anthony said...
    mcfloyd, thanks for adding me to your feed reader. Aren't they great? I'm a big fan of Google Reader.

    In my opinion, raised beds are all about the deep soil. Dig a hole in your yard and you'll probably find that they's only 6 inches of top soil. With a 6" raised bed, you've just doubled the amount of space for your plant's root system.

    Plus that root system is breathing better because you're avoiding soil compaction by not walking (I hope) in your beds. And they drain better which helps the roots breath better too. Healthier roots means healthier plants.

    Hope that information helps. And don't forget that you don't have to bend down as far to garden in a raised bed. :)
    johnnyb said...
    To add to the pressure treated question.

    Pressure treated is my family business, and I would like to offer a fair opinion backed with research and personal experience. I am a fourth generation wood preserver.

    For many years, the choice of pressure treated lumber was wood treated with CCA, Chromated Copper Arsenate. However, CCA has become a thing of the past except for in certain specific commercial and industrial markets. Let me assure you, it would not be easy for the average consumer to get their hands on it since the voluntary transition to newer, and safer chemicals.

    Which brought us ACQ and Copper Azole. ACQ stands for Alkaline Copper Quaternary. The Alkaline holds the copper in a liquid form, and the quaternary is basically an anti-bacterial soap. Much better in many ways. However, as the author has pointed out, there is a flaw in this chemical. It corrodes aluminum as well as other metals. CCA and the other two choices have always recommended using stainless steel or other approved fasteners, however, the new guys on the block seem to have the predominant problem of corrosion.

    Why does it really corrode? Copper doesn't get along with aluminum. Simple chemistry. The nature of this treatment allows a tiny amount of copper to leach out, which causes surface contact with any fastener. If that fastener happens to be aluminum, a chemical reaction occurs, and in a short time, maybe a couple years, no more fastener. But do not become discouraged. There is an even newer kid on the block.

    You will see it as a few different names: MCQ, Smart Sense, MicroPro, MicroShades, or Micronized Copper Quaternary. ACQ is held in solution, a liquid. MCQ is chemically different. It is made of tiny (micro) particles of copper. These particles are forced into the wood cells or pores during the pressure cycle. Once in, they stay in, also forming a barrier keeping in the quaternary. The leaching of chemicals out of MCQ is practically non-existent. So much so that aluminum is actually approved for use on this type of treated wood.

    It just started going into production the end of 2006, and is becoming available in almost all states. If you can not find it, request it, or shop somewhere they do carry it. Most of the independent lumber yards will carry it, and Home Depot has it available in some stores as well.

    To add a side note, I purchase organic and/or natural produce when available. I did not want to use ACQ in my organic raised bed garden, if I had to, I would have use a liner. However, I am building raised beds this year, and dragging my feet paid off this time, because MCQ became available, and I trust the research behind this product. ACQ was the step away from CCA, MCQ is the step up to a new level of safer treated products. I hope this helps answer any questions. Thank you,

    John Bumby
    The Maine Wood Treaters
    Anthony said...
    JohnnyB, Thanks for sharing all that information. Obviously this is a topic that you know a lot about. Check back here again because I'm going to quote you in a new post on this topic.
    Anonymous said...
    I much prefer wooden compost heaps but the problem of using pressure treated woods has always worried me and despite searching on the web to find the relevant information I have been unable too. I find this comment about pressure treated woods both informative and reasuring that I can now continue to use my pressure treated compost heap with the knowledge that it is safe. Thank you johnnyb for posting that.

    Karen
    Anonymous said...
    The Great Southern Wood Company has this disclaimer on their Yella Wood (MCQ) webpage:

    "Do not use preserved wood under circumstances when the preservative may become a component of food, animal feed or beehives."

    This is oddly worded to say the least, but it makes me think I don't want to use it next to my vegetables...

    David P

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