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pine vs cedar for raised bed

Posted by rersoap z6 Pittsburgh (My Page) on
Mon, May 9, 05 at 13:37

I am building 2 4'x8' raised beds. Last year I built 3 with cedar but this year I am having problems finding the cedar and was thinking about using 2 2x6 untreated pine from the local depot/lowes. Has anyone used the regular pine and if so, how long has it lasted? I can put boiled linseed oil on it or any other clear/tinted finish that would make it safe for veggies. thanks, rich


Follow-Up Postings:

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RE: pine vs cedar for raised bed

Rich, I just built a bed out of cedar and was wondering how your's held up?


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RE: pine vs cedar for raised bed

After one year it is still doing fine. I used two 1x6 boards for the sides and used 6x6 black locust for the corners. The corner pieces are approx 18" inches long so they go into the ground and anchor the bed in place. They also gave me something to attach the boards onto. I forgot what I used to coat the boards, some type of sealer. So far, so good. Just cannot find cedar. rich


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RE: pine vs cedar for raised bed

I was just wondering about that, the coating of the wood. I'm assuming that all cedar is treated, so I should plan on coating or lining my bed this weekend.

Thanks!


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RE: pine vs cedar for raised bed

  • Posted by Riff z7 NorthernVA (My Page) on
    Mon, May 9, 05 at 22:13

Rich, I built my first bed in spring 2003 of plain 2-by-8 construction lumber (spruce-pine-fir) from Home Depot. I didn't coat or seal it with anything. It's going on its third year now, and will last at least another year and probably a few more, from the looks of it. My current *guess* is that it will last five to seven years total. I'm in the northern Virginia area (hot, humid summer, pretty wet winter and spring).

I built two more beds in the fall 2004 with the same lumber, but applied boiled linseed oil to it. I don't think it will make a big difference; I just happened to have it around and was curious. Given that my plain untreated, uncoated bed is holding out so well, I'm not sure it was worth the effort. Too soon to tell if it will make much difference. I'd think hard before I used any other coating or sealer because I'd worry about the chemicals in it.

By the way, Rich, where did you get black locust 6x6 posts? That sounds great -- black locust is supposed to be very decay resistant, isn't it? Wish I could get some!

Dazzlemewithcolor, I would assume most cedar (as bought) is *not* treated with anything, since it's pretty decay-resistant naturally. (That's why it's popular for outdoor use.) I'm not saying it couldn't be, but I've never heard of pressure-treated cedar.

--Riff.


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RE: pine vs cedar for raised bed

Riff, I got the black locust from my back yard. When I moved in I had two large trees in the yard. The previous owner had the topped and they were looking quite sad. Also, they were not the thornless variety so the branches had thorns. I decided to cut them down and had them hauled away and made into boards and 6x6 posts. The stuff is hard as a rock and does not rot (at least not too fast). Growing up, we used locust all the time for fence posts. Good stuff. rich


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RE: pine vs cedar for raised bed

Riff, thanks for the info. I couldn't remember seeing that the cedar was labeled 'treated'. I'm going to call the lumber yard and just verify. If it's not, it'll save me from having to line it with plastic.
On the recommendation (sorry rich, I hope you don't think I'm trying to hijack your post), of a wood worker, he suggested making our own deck sealer using boiled linseed. To be honest, it didn't work that well. I went back to using a deck stain. So, I'm not sure that using it the beds would be that beneficial.


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RE: pine vs cedar for raised bed

Riff, don't even think about trying to hijack my post or I will smite your garden, just kidding. The cedar that I used last year was not treated, but I put a finish on it. Just not sure what I used. I called BEHR today and asked about the safety of their semi-transparent deck finish. They said that if it is below grade (one side will be) that they do not recommend it. They do have a product for below grade but do not recommend it for veggies. I might try the boiled linseed oil. One other thing that I did was to attach wire hardware mesh to the bottom of the bed to hopefully keep moles from coming up. Not sure if it will work or not but so far, no moles. One thing that I may do is still use the same sealer as last year but not put it on the inside of the bed. Keep the outside looking nice and let the wood touch the ground on the inside. Anyone with suggestions? rich


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RE: pine vs cedar for raised bed

  • Posted by Riff z7 NorthernVA (My Page) on
    Tue, May 10, 05 at 21:17

Rich, great that you had the black locust trees made into useable lumber! I'd forgotten that those trees had thorns, never having seen any around here. I like to read books (and dream) about timber framing, and I think that's where I saw that black locust is supposed to be good for fence posts and the sill plates (the bottom timbers). I'll bet BEHR didn't recommend their deck finish for below grade because it's probably just not very effective with direct earth contact. That's why I've pretty much decided on plain untreated uncoated lumber, cedar (or black locust!) if I can get it, or regular spruce-pine-fir (SPF) construction lumber otherwise. At least until I can afford a recycled plastic or plastic-wood composite (like Trex) lumber! That would be ideal, lasting pretty much forever, but still to expensive for now.

Dazzleme, assuming your cedar is untreated, I'd just use it plain. From what I can tell about boiled linseed oil, its protection only lasts a year or maybe two. I do use it for some other things though (sandbox, trailer sides), because of what I see as a big advantage: you can re-apply easily, whenever the wood looks dry, without any labor-intensive scraping, since it never peels or loosens as some paint and stain (maybe?) can. Its usefulness comes from soaking into the wood, instead of forming a surface coat that must adhere to the wood.

--Riff.


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RE: pine vs cedar for raised bed

Riff~ HOws thats untreated pine doing. I'm think about building a big raised bed for flowers using just plain pine... I'd like it to last 10 years, but less would do...


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RE: pine vs cedar for raised bed

Most of my beds are un-treated cedar 1x6 installed in the early 90's. Still usable altho I think it'll need to be replaced in a year or so for apperance purposes. Have 3 small beds in 2x4 pine [also un-treated] and I've repalced them one time in the same time period. IMO you shouldn't use ANY type of treated wood for veggie beds. The reason you have to reapply the finish is that it has leeched out of the wood - into your bed. Cedar is hard to find here at this time.

don


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RE: pine vs cedar for raised bed

Cedar Wood Vs.Pressure Treated Pine

Aromatic Red Cedar: Cedar is a very stable wood. It does not warp, or shrink, or check (as pressure treated pine most likely will do eventually). A product using cedar boards will have a much nicer appearance, after 10 years compared to a pressure treated pine. Our cedar usually comes from Missouri, Oklahoma, Ohio, Kentucky, and Indiana. It can be 50-80 years old. Cedar lumber costs a little more than the fast grown southern yellow pine, but it is well worth the extra expense. Cedar could last 30 years or more and will stay straight!

Pressure Treated Pine: This type of lumber usually originates from the southeastern U.S., and can be a southern yellow pine species or a mixed pine species. It is a fast growing tree; being one of the few types that can be pressure treated. Other types of wood have a different cell structure and will not accept the treatment process.

This pine, after it has been cut to size, is kiln dried to remove most of the moisture. Then it is bundled up and put into huge cylindrical tanks. Next, a water based solution of micronized copper azole is forced into the wood fibers under pressure. This process makes the wood very heavy and gives it a dark green appearance.

This pressure treated pine (PT pine) is guaranteed by the manufacturer not to decay or have insect damage for 10 years or more. It is not guaranteed against shrinkage, warping, checking (splitting). We do not guarantee that this will not happen because it often does. When PT pine starts drying out it can develop "checks" which look like splits or cracks in the posts or boards. This is not an uncommon complaint from new owners of wood products. Actually, the wood is slightly shrinking, a natural seasoning (drying out) of any piece of lumber.

When a fence post dries, the outer surface (sapwood) shrinks faster than the inner heart of the piece, and something has to give. For this reason, posts have a natural tendency to develop a V-shaped check towards the center. The result is the familiar "check" which is technically neither a split nor a crack.

Depending on the weather and season your wood fence is installed, checking may occur right away, or might wait for warmer weather. We usually never use PT pine for the posts because they will decay in the ground must faster than a cedar post would. Because of this we only use cedar posts for fencing.

Here is a link that might be useful: cedar


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RE: pine vs cedar for raised bed

I don't see anything wrong with using untreated pine in raised beds. You may want to paint the wood with Kilz white oil based primer... or a boiled linseed oil. Straight pine without the paint or oil can last up to seven years provided that you have a good draining soil. You may decide in four years that it is time to move your beds around, and pine is a lot less expensive than cedar.

There is a trick to keep your fence posts from rotting. It's called tamping. If you can tamp the soil around your posts, your posts can outlast the fence or beds above ground. A lot of posts that replaced hedge trees in the Midwest that have been in the ground for 150+ years have been tamped into he soil. (They are also made of hedge trees called Osage Orange.)

All wood is biodegradable no matter how hard the wood. If you were building a fence for your yard, I would suggest using cedar posts. You want longevity for a raised bed, go get stones or concrete blocks.

Here is a link that might be useful: Art Blog


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