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11 messages
26/07/2013 at 20:52

Hello.

I was hoping to get a little advice if possible.

Somewhat impulsively today, I bought a number of 6 x 1 in planks of pressure treated timber from a well known builders merchants and constructed a small raised bed (2m x 1m) with the view to growing veg/herbs. After much work in the hot sun, I've a rather lovely little raised bed which I'm rather proud of. 

However....

My next door neighbour mentioned to me that pressure treated timber can contain toxic chemicals that leach into the soil and therefore into any crops grown nearby. This has obviously casued me worry and concern. I've looked on the spec for the timber and it says that the wood is "High Pressure treated with Tanalith 'E' (or similar)" I'm now unsure as to whether I'm OK to go ahead and use my new bed or whether I'm looking at having to start all over again?

Any advice would be very welcome.

Thanks in advance,

Dr1974

26/07/2013 at 21:02

Found this in Google. Should be no problem for a raised bed..

  • Can I use Tanalith® E treated timber around food, water, vegetables or other plants?
  • Treated timber in general should not be used in direct contact with human food or drinking water during storage or preparation. Incidental contact of food with treated timber, such as in play grounds, picnic tables, decks and pools is fine as there is little or no potential for migration of the preservative constituents onto the food. Similarly treated timber is suitable for raised flower or vegetable beds, gardens, landscaping, mushroom trays, grape and tomato stakes, greenhouse uses and similar applications.

    26/07/2013 at 21:45

    Hi, Dr

    I'm not an expert, but googled Tanalith 'E'. There's alot on information on line. This is what I found- 

    ... it's a waterborne product based on copper triazole technology.  Copper is derived from recycled sources and triazoles are organic biodegradable biocides, commonly used to protect many of the food crops we eat.  TANALISED pressure treated timber is usually specified for both in and out of ground contact applications where there is a medium to high risk of decay or insect attack. 

    sounds ok to use on raised beds. A further google search said if the wood has been treated prior to being used as a raised bed and not treated afterwards as a preserve it is ok to grow veg oganically.

     It can be difficult when making raised beds from wood to decide what to use to preserve the wood if you grow veg in the beds. Mine are wooden and I didn't pay to much attention to preserving them, two were bought online fit for purpose and a third was constructed from scafolding boards. 

    I'm sure other posters will be able to give further advise but as you've made the beds and if concerned about stuff leaching into the soil you could further line the wood on the insde of the raised bed with plastic.

    26/07/2013 at 21:49

    very useful Sue & Zoomer. & good for you Dr1974 exercising your DIY skills, are you planning on making a netting cover for it?

    26/07/2013 at 22:26

    Thank you all so much for such quick responses and managing to uncover what I couldn't. 

    Yes, a liner is my thought also, just to be on the safe side. 

    ZombieG, I will end up netting it I think to protect from birds/cats etc. Is that what you were thinking?

     

    26/07/2013 at 22:58

    I've used tanalised decking boards for raised beds.  I thought about lining it, but to be honest I doubt it would present any real barrier and would be a haven for slugs and snails.  

    If you've cut the timber you can use boiled linseed oil to protect the edges from rot instead of "shed paint".  As long as you get the boiled stuff and not the ones that use metallic driers (cobalt etc - very toxic) it is very safe - I use it on my chicken coop for this very reason.

    27/07/2013 at 12:46

    Hi Dr1974.

    Firstly congratualtions on making your own raised beds yourself, rather than buying them- They are a silly price to buy

    I am a Chemistry Technician by trade and my advice to you is that yes the Tanalith 'E' treated wood should be okay to use. This is because (unlike traditional treatments) Tanalith 'E' does NOT contain Chromium or Arsenic compounds-it contains organic biocides which are generally much safer.

    I would however still line the raised bed using a waterproof material (Tanalith 'E' is water soluable and the wood is treated by soaking in Tanalith 'E' and then vacuum pressured). Whilst not hazardous in the levels in your wood, the organic biocides can affect good microbe soil health over a time period of 1-2 years (Tanalith 'E' biocide is meant to prevent microbes rotting wood). A simple waterproof lining with drainage holes in the bottom (away from the wood) will suffice.

    Hope this helps!

    CrazyCat

    27/07/2013 at 23:35

    Hi CrazyCat.

    That's really great advice (as is all of the other advcie here). Thanks so much.

    Yes, I'm planning on lining the sides of the bed with a plastic membrane. I know many people are against it as it can trap moisture between it and the timber, thus increasing the potential to rot as well as making ahaven for slugs/snails but I'm happy to see how this goes initially.

    Looking forward to the rain easing here so I can get back out and sort the last bits of the bed out.

    Best,

     

    Dr

    29/07/2013 at 16:08

    Nice to see someone making their own beds! I'm going to build some too, starting either this year or start of next spring, but I'm using brick, as I want them to last the rest of my life.

    02/08/2013 at 09:14

    Hi did you get your wood from B&Q ? I have been buying my wood from diffrent places over the last two years and have had great veg from all the beds total of ten large ones  I leave the edges and corners to grow herbs and flowers with great success, I think you have to try it. 

    02/08/2013 at 09:53

    I have used surplus pvc. plastic soffit/facia board for outside shelving to stand flower pots on on my patio, with every success.Will be moving house soon to a larger garden and will make raised beds using the above.

    I will also use the total mulching system as explained in "Back to Eden" web site in "U tube" makes a lot of sense. Any one else out there tried it yet ?

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