I am going to make some raised beds in my garden to grow vegetables as the present soil is heavy clay. I already had a small raised bed made from 2ft by 6in edging slabs and the difference in yeild was startling. I imagine lengths 8in by 2in timber would be ok so what would be the best and prefeably cheap timber to use? And what should it be treated with?
Jan
After a few years there is some minor rotting on some of the inside faces
They are so cheap I will just replace them when they get too bad
I suspect that this will not be for some years yet
Tony
From a builders merchant or timber merchant, you'll pay about =A33/metre for 8 by 2 floor joists - ask for regularised and treated (the usual spec) - or even say you're using them for gardening and see if they have anything they can't sell for construction due to warping or splitting etc.
Alternatively ask any builders you see demolishing a domestic property
- they'll probably let you have the joists for little or nothing - but you'll probably have to de-nail them.
I made some last year. I went to a scaffolding company and he let me have a load of scaffold planks that were damaged for a few quid. These are about 8" x 2" thick sturdy pieces and are presumably pressure treated for their outdoor life. I'm just about to build more beds and I will get some more.
Painters10
Well, sorry to diappoint you..
My wife wanted some. She said 'scaffold planks - you have some left by the scaffolders'.
Sadly wen I picked them up from tehe back of the shed they fell to pieces. Rotten through.
then I board some 8x1 boards. They are still running, but looked ugly and only went up ..8"!
so then her next idea was to fence the vegetable garden, but then that idea changed, so I got left with a load of split rail fencing. So we whacked in some pressure treated 4x4 posts, nailed split rail (pressure treated) to it, and chainsawed off the surplus posts: Result! and if you leave the posts longer, you can add another rail later and make them higher. Looks very nice and 'rustic' unlike the sawn board.
So instead of blockwork (which is another good idea: concrete blocks mortared and bow tied together, or brick) try split rail fencing stock. Made a giant compost heap as well..currently filled with about a years output from a pony..
I'd avoid treated timber unless you think the copper, chromium, and arsenic oxides will improve your lettuces and your health! I'm using plastic bins. Concrete or bricks or untreated hardwood railway sleepers could be considered.
If all the treatment washed out at the first rains, it wouldn't be much of a treatment would it?
With raised beds largely it will go straight down the walls anyway. Not percolate into the bed.
Oh, and plants are pretty good at dealing with metal salts, many of which they actually NEED for growth.
Don't potatoes MAKE arsenic all by themselves?
Use CCA [Copper Chrome Arsenic] (sorry its not called that any more) Tanalth but make sure you get the timbers the size you want either by special request or using standard sizes for your bed Don not cut it! do not nail it but bind it in other ways or use copper nails on stainless strapping Matty is not correct in that the 'A' is no longer allowed and the heavy metal ions are chemically fixed to the hydroxyl groups and cannot leach out - that is the idea! That is why it is OK for kiddies playgrounds The only removal is by fungi translocating and you are not likel to get that in you carrots! Chris
Some people disagree that CCA is OK for gardens and playgrounds. In fact many countries ban CCA timber in playgrounds. If there is a non- CCA alternative I'd use that instead.
These worries were confirmed in spring 1997 by alarming reports from the USA. Researchers found that decks made from tanalised timber can leach high amounts of arsenic into nearby soil. Samples taken from beneath treated decking contained up to 80 times more arsenic than surrounding soil and as much as 35 times the legal limit for arsenic in the soil. The study found that arsenic leaches quickly from treated wood..."
I'd suggest reading this before deciding if you want to machine any tanalised timber.
The point being they are talking *organic*. A lot of things are not allowed in organic schemes that are otherwise fine.
Decks are horizontal and any leaching could indeed fall to the soil, but you don't grow veg below a deck.
Sorry, but you've still not presented anything to say tanalised timber shouldn't be used for edging raised beds.
MBQ
Dear Matty Since 2004 in the EU 'CCA' is not based on that as you suggest as the A has been removed! Of what possible relevance is this to my recommendation? I stated that the A (arsenic of cca) was no longer used. see
The EU amendment therefore restricts the marketing and use of both the CCA chemical as well as timber treated with CCA, and will also apply to imported treated wood and waste wood in re-use. In addition, it is anticipated that from 2007, CCA preservatives will require authorisation according to The Biocidal Products Directive (BPD)19 (Enviros Consulting et al, 2004). The EU regulations, however, do not apply to CCA-treated wood already in service. CCA-treated timber has not been as extensively used in Europe as it has in Australia however."
The evidence from Au and NZ does not take into account the differences in their treatment specifications compared with the UK (8 kgs p m3 versus 4 for a kick off) and I could not agree more with the delightlfully apposite comment of Huge!
CCA has stopped being used not because of its record but because "The CSTEE could not establish the arsenic-related risks of landfill disposal of CCA-treated timber, which is classified as a hazardous waste by the Commission in 2000, and thus concluded that it was appropriate to apply the precautionary principle and, in the absence of proof of harm, reduce the production of CCA-treated timber as much as possible because it is likely to cause serious harm (CSTEE, 2003)."
See
I woould be delighted to see references to any journal that has produced evidence the PROPERLY FIXED CCA IN SOFTWOOD SAWN (NOT POLES) treated to EU or UK standards leeches as it was my understanding that if it was properly allowed to fix in the plant that the metals ions were chemically fixed to the hydroxyl groups of the cellulose. Please will some of you budding ecolocial chemists show me that I am wrong in my understanding? Please, however, no anecdotal blogs,
Chris
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