staining wood for raised beds.

johnmcd348July 24, 2009

I'm wanting to build a raised bed and first went out and bought some pressure treated 1x8's and cut them and then later read about how it was a bad idea to use treated lumber due to the chemicals and such used in the treatments so I'm still at the beginning of my project.

So my question is that if I buy the regular kiln dried stuff, what is best to use in order to keep it from rotting out quickly in the harsh wet Florida outdoors?


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I was looking online through the local BB hardware stores and the Lowe's in my area has 1x8x8 Cedar boards in stock. Would those be better to use? Untreated, they were not listed as Kiln Dried so I assume they are natural. I think I saw 1x6x8 Kiln Dried boards available online also. I want to build a long bed deep enough to grow vegetables in. I would like to be able to grow nearly anything including carrots so I think I need to look more to the 8" wide and possibly build a second higher elevation for the other root type vegetables.

Am I on the right path or still spinning my wheels?


    Bookmark   July 24, 2009 at 2:25AM
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Hi John. You might want to try searching the forums as there is a lot of info on what materials to use for raised beds, etc.

But what I have read in my raised bed research is the following:

a) Use red cedar as cedar has natural anti-fungal properties that will make it last longer
b) use untreated pine or another wood but expect it to only last 3 to 5 years
c) treat the pine with a food-safe sealant like boiled linseed oil

I am using untreated pine and pine with linseed oil because I have only found the cedar in 1" thickness. I don't know if you know this, but for a raised bed you usually want to use 2" thickness because it reduces the risk of "bowing out" which is when the pressure from the weight of the soil inside pushes the boards outward. Pine is also much cheaper.

As for the dimensions, you want at least 10" of depth so that your veggies can send long roots down. Also, anything longer than 6' will bow out more. You may want to try bed that are 4X4 or 4X6 first. For my 4X6 and 4X4 beds, I bought 2X12X12 high grade pine at Lowes (14.58 each board), had them cut, used L braces and 1.5 inch deck screws (last longer). So far so good!

Also remember to "level" the bed on the ground (meaning one side may be higher than the other bc of the ground so use rocks, etc. on the low side to raise it up). This will prevent water from pooling on one side and causing a wet area (that will cause problems later).

Also, try looking up raised bed videos on youtube for instructions.


    Bookmark   July 24, 2009 at 8:02AM
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We used the 1" cedar boards from Lowe's and braced them every few feet. The beds have been holding up very well (no bowing, no rotting) in the year that we've had them, but I still don't know about long-term yet.

    Bookmark   July 24, 2009 at 9:04AM
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I've posted this at least twice, but it's worth repeating. Maybe someone sells a safe version, but definitely do read the label carefully.

Not to be an alarmist, but I absolutely wouldn't use boiled linseed oil on anything that would come in contact with my food. Raw linseed oil (flax seed oil) is fine, but boiled linseed oil contains various heavy metals that speed the drying time (raw linseed oil can take weeks to dry).

From the warning label:

"Use of this product will expose you to arsenic, beryllium, chromium, cadmium and nickel, which are known to cause cancer; and lead which is known to cause birth defects and other reproductive harm."

    Bookmark   July 24, 2009 at 11:19PM
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We are located in Ontario Canada. Two years ago my grandchildren initiated this project to grow our own vegetables and therefore we set about building four large garden beds. Looking for an Eco safe and earth friendly protective stain for the wood, I came across Eco Safe Wood treatment made by Tallearth and it was available on Amazon. We applied this treatment inside and out on all the beds. The wood is Fir which is cheap although not recommended for outdoor use as it is a soft wood. The wood turned a lovely olive brown color and currently has a silvery aged finish. After two years the beds look brand new with no sign of mould or rot anywhere. Happy to share this information.

    Bookmark   January 26, 2015 at 1:36PM
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