I am building up my garden beds with tanalised timber and was wondering if the Chemicals (As, Co) will leach into the soil and contaminate my soil/vege?
gabbysnana,
Jul 17, 1:32am
You line them with the heavy grade black plastic.
luvwine,
Jul 17, 1:39am
From what I can remember reading, yes it can leach in but there are mixed opinions on whether this is at a quantity/ rate actually cause any harm . Easy enough to line with heavy polythene to stop you worrying about it
happychappy50,
Jul 17, 1:44am
Yes,line with heavy duty plastic,will stop any leaching which would be minimal but protects the softwood(pine) from too much moisture,also could help retain moisture in the soil when it warms up.
mm12345,
Jul 17, 1:45am
There are mixed opinions. The US EPA has a very grim view. Not sure where OP got "Co" from. There's "Cu", but it's the Cr(vi) and As which are more of a concern, how much leaches out and under which conditions. IMO, EPA probably overreact, but I wouldn't use tanalised timber for vege garden edging myself.
aj.2.,
Jul 17, 1:56am
Use a natural hardwood, that way no worry with any chemicals leakage.
survivalkiwi,
Jul 17, 2:57am
Yes the greenys will tell you. But try to find someone who has had bad effects from eating vegies from a treated timber raised garden bed.
roys351,
Jul 17, 4:24am
mine are made from tani timber they are raised. and the way I think is the water is going the wrong way to push tannins into the gardens. got to be better than getting them from commercial growers that use all types of sprays on the soil and ground
macandrosie,
Jul 17, 5:01am
The problem is with the plastic liner is that your'e not going to allow your soil to breathe, if it doesn't have holes in it you won't create a healthy environment for earthworms.
mack77,
Jul 17, 5:30am
I think that the most suitable material to make garden beds with is concrete; it's cheap, long lasting and non toxic( I think?).
smallwoods,
Jul 17, 5:51am
The EPA were up in arms about childrens play gounds and the leaching. The leaching comes from either the treated material being installed while still "wet" or the natural action of the rain hitting the post and causing "run off". In your raised garden the water would be running away from the plants(unless you were soaking the sides inwards) and as for the plastic, don't cover the bottom of the beds.
russell.s.c,
Jul 17, 5:53am
Your evidence is?
roys351,
Jul 17, 6:00am
common sense. unless gravity has been reversed. water in water out
russell.s.c,
Jul 17, 6:09am
It's common sense that lining the sides doesn't stop water getting out so there isn't a water problem unless it's over-watered but that's a problem in any garden.
lythande1,
Jul 17, 2:12pm
Yes it does leach. The affects may take a long time, but they are there. Use untreated macrocarpa or something if you must have wooden sides on it. Or as someone else suggested - concrete. This house I have now has two raised gardens made from concrete blocks - the curved ones.
Or just don't have it raised at all. bit of a fashion thing these days, food gardens were straight in the ground for years.
Or brick perhaps if you have to have them up off the ground.
Plastic liners and such will just make your soil under it rubbish, gardens are an eco-system you know, not a sandpit.
jonners2013,
Jul 17, 2:31pm
The problem is that as lovely as macrocarpa sleepers are, they are a hell of a lot more expensive than say treated t and g retaining wall timbers.
cantabman1,
Jul 17, 2:41pm
I am in the process of re-building a raised bed. The existing natural timber has all rotted, so I am replacing it with treated timber [all scronged off cuts] and slightly extending it.As before it will be lined with black polythene. Holes will be punched in the bottom. With the lining to protect any contamination directly to the soil, I cannot see any problems.
happychappy50,
Jul 17, 3:02pm
Mine abound with worm life,as the underside is on soil,only sides are covered in plastic,blows that theory.I have also painted a mixture of boiled linseed oil & diesel on to the exposed timber to stop any cracking in the hot sun,linseed oil helps to nourish the timber.
maccachic1,
Jul 17, 4:19pm
I stained mine and the wood is lined with black plastic the top of the garden is open to the air so plenty available to the soil and the bottom isn't lined as what is the point.
jan2242,
Jul 17, 6:30pm
I heard Tony Murrell asked about treated timber leaching etc. He said he had never heard that this happens. All my gardens are raised, tanalised, no problems that I know of? No idea how you would test the soil to find out?
maccachic1,
Jul 17, 6:33pm
Treated timber def leaches when constantly exposed to water - that why it is the last line of defence in a house. Weather this is taken into your veges not something I would risk myself.
smallwoods,
Jul 17, 6:38pm
Any good lab will test the soil. As a poster said, plastic against the treated timber leaving the bottom open. By raising the beds gives you better drainage(normally) and raises the temperature of the soil for longer growing season, though watering is needed more often.
lythande1,
Jul 17, 6:54pm
Yes. But is the point cheapness or health? And. like I said, concrete, brick or no edging at all.
spiritofgonzo,
Jul 17, 6:58pm
and just how are we going to find those results praytell? Not as easy as all that. Unless we set 100 people up with tested tantalised raised garden beds and 100 without, and monitor them all anually for 50 years.
macandrosie,
Jul 18, 1:50am
russell.s.c your soil will become waterlogged if there are no holes in the plastic. Soil naturally needs aerating. It's a practice all farmers know. Stock pug soil if it's too wet, it damages the soil structure & then grass won't grow. If you are only lining the sides & covering the timber that's a little different. Leaving the bottom free of plastic is a great idea.
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