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I'm planning out my garden build and I'm trying to figure out the most economical way of doing so. I'd like to build my beds out of something rot resistant, chemical free, and affordable. My garden will have four 5'x3' boxes and two 1'x8' boxes. To build these boxes out of typical cedar wood will cost nearly $200 more than my other alternatives.

I'm considering framing 10" strips of these asphalt roofing panels with cedar and building the boxes that way. My question is, are there any health concerns I should be aware of if using these panels? From the manufacturer's website, I got this information:

ONDURA roofing sheets and tiles are comprised of 50% recycled organic fibers that are processed to increase durability, formed into a corrugated panel, and then infused with asphalt to create a weather protection barrier.

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    Organic means anything with a C atom; includes petroleum and plastics...ha ha ha. I always have raised beds without sides. I'll send a picture of my garden the beds are 5 years old... – stormy Apr 26 '18 at 19:57
  • But interesting idea...have you checked out Treks brand dimensional lumber? – stormy Apr 26 '18 at 20:03
  • I decided to go with corrugated steel instead. Probably more structurally dependable and I don't have to worry about any possible toxins in my soil. Only a little more expensive. – DannyM Apr 26 '18 at 20:39
  • Much better choice. If asphalt shingles were chemically safe we'd be using them for an awful lot more applications than roofs. I've been working on getting my SD card to work on this computer so here is a picture of my garden...last year. – stormy Apr 26 '18 at 21:46
  • I used ONDURA on the roof of my garage. First few years it got pretty stinky in there on hot days. Stuff's lasted 10 plus years now though. OTOH, steel does not outgas much. – Wayfaring Stranger Jun 10 '18 at 14:30
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I have used old rail road timbers before, but was disappointed with the outcome of the plants (veggies) that grew closest to them. Asphalt is used to "cure" these timbers and is of course very toxic to them. Humans can also get sick from asphalt.

So to answer your question, no (sorry) asphalt for anything in your "organic garden" is not good to use. I know regular timbers are not treated and will rot, but that is the organic natural way the earth works. You'll also find that as any petroleum based chemicals are used your plant will stay smaller, the blooms may "rot off" ( failure to launch). Here is a link that tells more about petro chemical timbers /asphalt uses in gardens.

As an organic grower myself I advise any grower to stay away from "treated (including pressure treated) timber(s). You simply cannot be an "organic" farmer /grower on top of chemical treated timber for raised beds. Hope I didn't disappoint with this response. Happy growing ( we all need to teach and learn to grow our own food and I applaud you for doing so).

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notice the trenches along the bottom of the slopes. This soil is like sand; volcanic pumice. These beds are 4 years old. Double dug the first time and this is virgin Pre-ponderosa pine forest of Jack and Lodge pole pine. Zippo organic matter and clay. I dumped decomposed organic matter on top twice a year, also do cover crop, the soil is wonderful now.

This type of raised bed is hate to use this word...more organic than beds with structural element sides.

I threw Decomposed Organic matter (I bought in bales only partially decomposed) into the mound of soil I dug by shovel fulls. The process of making these raised beds looks fairly overwhelming as you dig. Digging down at least one foot...you'll be getting top soil mixed with the next horizon that will be more subsoil. The only thing I add is a shovel full or two as I make these huge piles of fluffed up soil. That is it. Rake it down, I get a chunk of plywood and throw it on top and jump up and down to compact (believe it or not) the soil I just fluffed. Then I dig those little trenches at the bottom throwing more soil on top of the bed from the trench digging/cleaning out. Then raking and plywood compressing. Practice flipping the soil on the slopes UP and over the top of the bed using a metal leaf rake. Once you've firmed the soil of the bed you are ready to plant your starts (acclimated first of course) or seed. I plant the entire top of the bed using offset, no lines ever. Wastes so much garden bed realty. Spacing and depth are all taken into consideration. No fertilizer until plants have at least their 2nd true set of leaves, or when I transplant my starts from my grow room, acclimated for a few weeks and plant in the garden soil. From indoor grow room to green house environment, I acclimate at least a week or so bringing in the trays of 4" pots of started plants.

Warmer soil, incredible drainage (I do this with clay soils as well), forget weeds if you are 'dosing' your beds with decomposed organic matter around the plants; fine to do a little around starts. Do not dump this DOM on top of germinating seeds. After the plants have produced their 2 or 3rd set of leaves, you can dump DOM on top of the soil, up to 2 inches depending on the crop.

In the spring, just cleaning out the trenches dumping that soil on top of the bed, adding DOM, rake to mix a bit and use the plywood to firm...and you are ready to plant. The soil gets better every year...doesn't mean it is fertile!

Gosh, hope this helps. I've build raised beds in my line of work an awful lot using lumber, cinder block...and these beds are far easier and healthier because they are 'organically' being mixed and recycled. And I would never use garden soil in raised planters. Sorry. Raised planters with sides are the same as pots. I do put my old potting soil from the tomatoes and other plants planted in pots inside my greenhouse, on top of my beds (making note of brassica or solanaceae to dump that soil only on beds where those species have not been planted for two years...), I won't waste it!

Don't know your situation well but thought I'd get you another option I know works well. The beds in this picture are now under a greenhouse skin. I took pictures of this years beds. The difference in soil tilth is huge. Each of these beds was double dug once, a foot deep, more to get big tree roots removed, and I don't double dig ever again. Just 'maintain' the soil's dynamics of drainage and tilth and the life in the soil of these beds with the humus is beautiful. I'll try to send the picture of this garden this last week. The difference between the soil in the beds and the walkways...black and white.

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