pressurized wood for raised beds

[Afric]

Hi to one and all, in particular Charles. This is my first time writing on the forum, so here we go. I am having raised beds constructed in order to start growing organic vegetables, more or less for the first time. The soil in our garden is very compact, containing a lot of clay and not draining well, so the raised beds are just the thing, also with a lower layer of stones to facilitate drainage
Francie, an excellent handyman who erects fences and boundary railings came and took the measurements for us and arrived yesterday to assemble the raised beds. I noted that the wood is pressurized treated, probably Tanalised, and asked Francie to check with his supplier re how exactly the wood was treated and whether it was of a grade/class that would be suitable for raised beds and the growing of organic vegetables. I am aware of the debate on the risks of using pressurized wood in raised beds in terms of the potential risk of leeching out of chemicals in to the soil but also read literature re choosing the correct USE class of pressurized wood that would be suitable for direct soil or water contact. Would it be best to avoid using pressurized wood at all (we have the option changing)? What would be the best wood to use?
I am in based in Ireland, Co. Donegal.
Thanks, Afric

[charles]

 Welcome to the forum Afric. Your beds sound a good plan, I am not sure that you need drainage stones, worms feeding on your beds’ ingredients should make drainage channels in the clay.

Apparently arsenic is the main ingredient to avoid in tanalised, pressure-treated timber, and I gather that many if not most treatments are now considered suitable for making beds for food. However I prefer to use untreated timber which I paint with a fungicide based on plant oils, see http://www.osmouk.com for example. I used their wood protector, one coat only before making the beds, on softwood planks for the beds of my experiment, six years ago, and they are still in good order.

[kate robinson]

Hi Afric,
I started a no dig salad growing patch last August. Having mulched with black silage plastic I simply covered the area with cow manure and then some compost. The edges gently slope away – I have no wooden edges. This saves a large amount of money and I have very few slugs – almost no slug damage to newly planted out seedlings. Good luck with your garden. K

[Afric]

Thanks K, sounded like a easy solution, however given the work that Francie had already done in assembling the pressurized wooden raised beds I just could not completely cancel the order. Francie had no problem exchanging the pressurized wood for natural wood ( is presently assembling the new raised beds) and we will coat with an organic protective oil.

I like the idea of no slugs as we have many, many slugs here. On a previous attempt to grow vegetables they ate everything. I actually think that we added the slugs to the vegetable patch as we added soil that had materialized in a neglected compost bin and I had noted little white balls mixed in the soil which I was told, somewhat later, were probably slug eggs, as slugs like to nest in poorly managed compost heaps.
Afric

[Afric]

Thanks Charles, it is so wonderful to get this advice on the forum. The drainage stones have arrived and have been wheel-barrowed to the back garden by Francie, who had already taken away the pressurized wood and replaced with natural, untreated wood, which he is assembling now! I have not the heart to send the stones away. We are going to call up to our local garden center and make sure that the under-lay we use will be as natural a product as is available. The worms will have less work to do and I will know this for the next time.
Thank you for the site on the fungicide based on plant oils. We actually have an organic Linseed varnish, used for wooden boats, “Le Tonkinois Linseed Classic Varnish”. Do you think this would be appropriate? (see http://www.solventfreepaint.com/linseed_varnish.htm)

Thanks,
Afric

[charles]

 It looks good but may be more cosmetically interesting than needed for your beds – I like the Osmo products for the way they soak right into wood and protect it from within, as opposed to making a ‘protective layer’ on top. Hence no flaking and cracking. I have not repainted my greenhouse since 2001 and it looks great, just a little faded. I think the paints are similar to wood protector, with pigment added.

[Afric]

Thanks for that, Charles, I understand what you mean.
It is just that we have two tins of Tonkinoise here, and as log as they are organic and safe to use it would be more practical for us to use it in order to get the beds ready for planting by early next week. Otherwise we would have to wait for the Osmo products to arrive by mail order before we could get on with that.
We are really excited about our gardening project.

[Author]

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