# Hardi plank for raised bed garden



## mas360 (Nov 21, 2006)

I am thinking about building a raised bed veggie garden. The construction will be out of treated 2x4 lumber buried 1' into ground with concrete at every 5' for posts. The wall is to be made of hardi plank, the type you use for house siding. I think hardi plank would last longer than cedar board with regard to rot issue. 
Do you think it is necessary to line the interior wall with plastic sheathing to provide further protection against moisture?


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## Meadowlark (Jul 19, 2008)

Generally, I worry about chemicals leaching into the soil from treated wood much more so than rotting wood...which is why cedar is preferred in my book.


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## WilliamH (May 21, 2004)

Hardi plank would be too flimsy. With supports at 5' on center I would think it would bow out with the weight of the soil.

Have you looked into using 4" wide cmu block for building a raised bed?

http://www.greenwizards.org/?q=node/1199


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## mas360 (Nov 21, 2006)

Meadowlark said:


> Generally, I worry about chemicals leaching into the soil from treated wood much more so than rotting wood...which is why cedar is preferred in my book.


I don't think Hardi plank would present the chemical issue as treated wood.


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## mas360 (Nov 21, 2006)

WilliamH said:


> Hardi plank would be too flimsy. With supports at 5' on center I would think it would bow out with the weight of the soil.
> 
> Have you looked into using 4" wide cmu block for building a raised bed?
> 
> http://www.greenwizards.org/?q=node/1199


Perhaps I'll reduce the span to 3' instead of 5'. I like Hardi plank for the look, no chemical issue and ability to stand up against water damage.


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## w_r_ranch (Jan 14, 2005)

William is right, hardi plank is to flimsy plus it's relatively brittle. You may want to look into using Trex or a similar composite product instead... since you like the 'raised grain look'.


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