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lumber for raised beds
What materials should we use for building our raised bed containers?

Question details

We are a group of "church ladies" (called Wild Women of Plumsted) and are planning an organic garden. We had hoped to have raised beds to make them more accessible to the older members, but are hearing that if we use untreated lumber it will only last 1-2 years. Would like benefit of others' experience.

I struggled with this question at home and settled on cedar. You certainly do not want to use pressure-treated lumber as it is impregnated with lots of nasty things that will get into your soil. Untreated pine may last more than 2 years, but not by much, but it certainly won't last as long as cedar (my beds are now 4 years old and look as good as they did at the end of the first summer). In comparison, the fence around my yard appears to have been made of untreated pine and is completely rotted where it contacts the soil. It is one year older than the cedar beds. There are a few non-toxic treatments that could be applied, or you could use stone or brick. Try reaching out to local lumber yards and home improvement stores. If you're doing this for charity, they may donate materials like cedar or at least give you a steep discount.
For my community garden plot, I mulled over that some idea. But wound up going with 1/2 in pine. The reason, I did want my beds to break down in 1-2 years (some started to go in year 3, the rest are about to see the start of year 4). I wanted to be able to easily re-arrange my garden. And I have been able to do that as some of my boxes break down. Now that I have a better idea of how I want the garden to be, my next beds will be of cedar or something with more permanence. For our school garden, we were limited in where we could plant and knew there wasn't going to be much of any re-arranging. I think we went with poplar.
Redwood or cedar make fine wood edging. My untreated Douglas fir 2 x 12's lasted about eight years, but I am in the desert southwest (climate definitely effects longevity). Other options could be water troughs for higher beds for better reach for some people. You can also look on craigslist or other sites for free brick, broken concrete, or rock to build permanent beds. Finally, untreated posts (large branches, tree trunks, etc.) put on end and buried some for stability would work well. You might find the material for free as well.
I don't believe that untreated lumber will last only 1-2 years. I just can't believe the wood would rot completely through in that amount of time.!!! The beds may not look as "pretty", and you might not be able to pick them up and move them after a few years, but, even if they start to decompose, it would take many years to rot through enough that they wouldn't hold in the soil. I use rough cedar 2x6 in 8' lengths and 4' widths. I use cedar 4x4s as posts in the 4 corners, and make the beds just 12" high. I do place them on tilled and amended soil, so my plants have at least 18" to put down roots, or more, depending on how ambitious I was tilling and amending the ground under the beds. I use screws like the ones in the photo above, drilling pilot holes through the 2x6s and into the 4x4s. The other material I've used for raised beds is broken concrete pieces. These are wonderful, a great re-puposing of materials, and the concrete adds calcium to the soil. There's some concern about other, less beneficial substances that might leech out of the concrete, though....I don't think I've planted veggies in these concrete pieces beds--just natives, ornamentals and herbs. Happy, happy gardening to you!
We used hemlock and it has lasted 5 years in a moist climate just fine. Our neighbor cut the tree down and we stripped the bark off and split the logs in half. Hemlock is generally a cheaper lumber, possibly because it is heavy. I'd recommend it for you as long as you do not need to move the beds around.
You might want to consider cinder blocks (concrete blocks). The only downside is that they are heavy so constructing your beds is a workout. But they are surprisingly attractive and hold up really well. The holds inside the blocks can also be used to anchor hoops for row covers. Here are a couple of websites with more info:
I will second njmatch3's suggestion on concrete blocks. All of my raised beds are concrete blocks. It is a bit of a workout initially but I've been very pleased with them. This year I am adding height to one of the beds to make it more accessible for both my Mom, who lives with me, and me (who isn't getting any younger). We've planted strawberries in the holes in the second level. They are doing very well.
I am new here and also newish to raised beds but the combined efforts of two chickens breaking out into leafy vegetable garden plus the not terminated by chickens snails has led me to raise some beds, at least to make a beginning. I am in southeast Australia, temperate near coast. My first raised bed was a huge dog bed formerly occupied by two Rottweilers, from a garage sale, almost free, now sitting on two large saw horses from the recycling at local rubbish dump. Now housing green salad gone bolting to seed, expecting self seedlings as we enter cooler months. My next raised bed the two halves of a leaking plastic tank 2 metres x 800 mm. These together sitting of course on a scrounged steel single bed base. This has salad greens in one, strawberries in the other. Filled with (1) an old curtain at the bottom to stop dirt loss through drain holes (2) drain layer of fine wood chips (3) layer of aged, rotted horse manure (4) body of compost in part domestic, in part from huge hot cooked heaps of grass cuttings that lawnmowing contractors happy to dump. The domestic portion of this also source of seedling tomatoes, tamarillos and to my surprise a single aubergine seedling! I now have a ditto double bed from dead tank getting filled, this one will mainly have strawberries, on the principle that you can never have enough strawberries. Also of course, peas and beans interplanted as season suggests. Having had a farm certified organic and having a permaculture design certificate, I tend to 'stack' plants—to get more from a given space than a given plant. You need to avoid damp problems with over-crowding but lots of plants like company. So my beds really raised, air under them, ok in a mild climate and with quality planting medium with high humus Thus good moisture retention. The snails can't get near, though I have seen them cause big problems hiding in nooks of solid from the ground box beds. Just to make them even more unhappy I am collecting eggshells, crushing them and putting this crushed stuff around the feet of my bed supports. Snails don't like walking over eggshells. My small garden has diverse microclimates. Shade areas, sunny hot, etc. My layout arises from exploiting that. Worth careful observation of the sun day, drainage, etc, working from there, building swales to collect runoff, etc. To understand where is warm, keep your eye on the dog! Discovering a wonderful hot spot in my front lawn, I got mixed reactions from neighbours: I have a crescent mound of ex-grass compost, initially writhing with worms, crowded with rhubarb in the centre of which a banana and at one end, passionfruit starting up over a metal archway ($2from rubbish tip). There is art in it, most important to me is that it is a system free to evolve, away from the notion of some gardeners near me that you lay it out and thereafter mow and prune to keep it the same. I found wrought iron railing at the tip and used that to shape garden space (the more you design 'rooms', the more interesting it becomes and the bigger it seems) and trail vines. Best wishes Dennis - my photo a couple of years old, when had a rural property with paulownia plantation, a tree being slabbed in photo.
We moved to middle Tennessee in March of 2012 and immediately built two new 4 X 8 raised beds. We purchased untreated 2 X 8s from Lowes and, acting on advice from a friend, coated them with raw Linseed Oil after we had cut them to length. It's only been a year but there is no sign, whatsoever, of any deterioration. I've just finished preparing wood in the same manner for two more additional boxes and expect many more years of use from them. I was told to use "raw" Linseed oil rather than "boiled" and so far it's worked well.
I suggest some a few simple measures can give your things that extra bit of protection while inside a self-storage container or container that can build more tough. <a href=""></a>



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