Raised bed sides, paint, finish, or nothing?

glimmer00(Z5, NH)May 28, 2005

Hi,

With the rain finally giving us (New Hampshire) a break I am getting ready to finish building my raised bed sqft garden. I'm contructing the beds out of untreated 2x10's and douglas fir posts. I know these are going to rot, but I have some concerns about pressure treated (the new stuff is safer, but I would like it to be out for a bit longer before planting veggies right next to it). Anyhow, I have read here about untreated lasting a number of years before replacement. My question is, would finishing the bed sides and posts (the design has corner posts in it) with exterior house paint pose a danger as far as anyone here knows? Will it leach anything into the soil? My aim here is to try and get a little more life out of the beds, given the time it is taking to make them, and I think I might like the appearance. Also, same question, with regards to exterior polyurethane.

My concerns for both of these are breakdown in the soil into something the plants can take up and then I will end up eating. Anyone have an opinion on this. I've tried searching the forums before, but most posts seem to be about what to make the bed out of (PT lumber, untreated, concrete block, etc) as opposed to putting a finish on untreated lumber(with the exception of boiled linseed oil).

Thanks in advance!

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Jacque_E_TX(Z 8a N Cent TX)

Howdy, glimmer00!

Well, I've used cinderblocks and air as bed sides with equal success. My opinion on the wood is, it will last several years, and then you only have to cut new pieces to length and screw them together around the soil--which isn't going to fall apart, especially if well-grown root systems are holding it together at the time.

I haven't read anything scarey about Latex in paint, or white pigment. However, I think the *interior* paints are the ones particularly formulated to be child safe. Some of our members have gotten good results with boiled linseed oil, or linseed oil with crushed carbon. Some are happy with sturdy rot-resistent wood, and some just snag a few cheap boards from the "seconds" pile at the home maintenance store....

Since I gave up tilling a huge plot every spring, I'm willing to replace a few boards every few years....

    Bookmark   May 28, 2005 at 3:18PM
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glimmer00(Z5, NH)

The only reason I ask is I haven't seen anyone post about, nor have I seen any info about exterior (figure best for outside) paint. I was thinking some decent house paint in a water base. I am also considering a recipe I found involving linseed oil, mineral spirits (as a carrier I think, will evaporate quickly I believe) and a small amount of melted parafin disolved in the mineral spirits. The wax I believe helps repel water. Haven't heard anything about parafin wax being horrible, and there is only about an ounce or so added per gallon. I may use tung oil instead as I have that on hand. I've got some of the beds built (pieces ready to screw together), waiting to finish sod removal and tilling prior to install.

Considered the cinder block BTW ... didn't want to lose the space to the block thickness.

-Allen

    Bookmark   May 28, 2005 at 9:14PM
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Riff(z7 NorthernVA)

Hi glimmer. I share your concerns about treated lumber. I haven't heard or read of any particular problems with exterior paint or polyurethane near food crops. I'd like to know, too.

Personally, for me, I would use exterior paint or polyurethane before I'd use even the new treated lumber, but I opted after all to go with some beds unfinished and some with boiled linseed oil.

If you learn anything, please let us know!

--Riff.

    Bookmark   May 28, 2005 at 10:02PM
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Ray_Scheel(z8b/SS31 E. TX)

Paraffin was not too long ago used as the primary way to seal canned foods and is considered food safe. Because of its properties I'm not sure its easily substitutable in that recipe.

    Bookmark   May 29, 2005 at 9:08AM
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glimmer00(Z5, NH)

Oops, I meant to say substitute tung oil for the linseed oil in the recipe(mineral spirits, tung oil, paraffin vs mineral spirits, linseed oil, paraffin). Thanks for the info on the food uses of paraffin, didn't know it was used as a food sealer. If its food safe one would certainly hope it is safe for most anything else.

-Allen

    Bookmark   May 29, 2005 at 9:49AM
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rickyr(Z7b-NorthMS)

I hope paraffin is safe, as I've eaten a fair amount of it over the years. We make peanut butter balls every Christmas that include paraffin in the recipe and I grew up eating 'em. My wife grew up eating them as well, so for the past twenty-eight years we get a shot at three batches each Christmas. FWIW, the recipe is along these lines - not sure if it is exactly like our recipe:

http://www.recipegoldmine.com/candybar/candybar84.html

I just finished (yesterday) building my sfg boxes out of untreated 2X12's and gave them a single coat of boiled linseed oil. We talked about painting them, but have decided to leave the as-is, with the linseed oil coating. I'm hoping to get at least five years out of them. Now, if you had asked five years from now, I could tell you how they're holding up. 8)

Ricky

    Bookmark   May 31, 2005 at 9:23AM
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glimmer00(Z5, NH)

Hmm, well paraffin must be pretty darn safe then, or at least I hope it is for your sake RickyR. The paraffin is to make the candy not stick together as much I take it? I dunno if I have had the peanut butter balls ever, but in my family there are frequently a lot of rum balls to be had around Christmas.

As of right now I think I've settled on the oil (linseed or tung ... as I mentioned above I have tung so that works in its favor), paraffin (small amount, about 1 ounce to the gallon), and mineral spirits as a solvent recipe. I MAY add, as in an improved version of the recipe, some spar polyurethane, as I think it may help and hopefully the small amount won't hurt things. I am making a rather complicated raised bed arrangment and am hoping to get a few more years out of them vs just using them 100% bare. Next version (when these rot) may be Trex or the like so I don't have to keep replacing them. In case any are interested here are links to some of the things I have been looking at:

http://www.attra.org/attra-pub/lumber.html#PreservativesAfter

http://www.organicgardening.com/feature/0,7518,s1-5-22-35,00.html

http://www.fpl.fs.fed.us/documnts/finlines/willi02a.pdf

None of these are likely the best way to not have wood rot. If the new pressure treatment looks safe in a number of years I might use it myself. However, as this is the veggie garden and not the flower garden I am trying to be a bit more cautious as I don't want to find out in 15 years that PT wood (new kind) has been linked to some odd condition in people that no one ever thought of. Thus the decision to use untreated wood and look for things that are very likely safe.

-Allen

    Bookmark   May 31, 2005 at 11:06AM
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NewB3

Hi all,
I read this post with interest, as I just built some raised beds with untreated pine and am now wondering whether to try to preserve them with something. I'd love to hear any updates one way or the other about how long things lasted and any issues that came up.
Thanks so much,
Maggie

    Bookmark   August 12, 2013 at 7:56AM
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