rasied vegtalble garden - Knowledgebase Question

Afton, Vi
Question by kerby5159
April 18, 2010
we built a 4x8x12 pressure treated rasied veg.garden. I now see on here it should not be treated wood. If we paint the inside before we put dirt in will that keep the chemcials from getting in veg. we eat? Or please tell me what to to..also does soaker hose go on top of soil ? Is 8 in. deep enough for tomatoes and other veg?

Answer from NGA
April 18, 2010


Pressure treated woods will last a long, long time in the garden and the newer treatments are much safer than the treatments of years ago. In the past, lumber was treated with CCA (chromated copper arsenate) which readily leached out into the soil. There are new processes for treating lumber now, specifically alkaline copper quaternary (ACQ) and copper azole (CA). They're very low in toxicity. I don't think there will be a problem with chemicals leaching into a flower or perennial bed, but I would still be concerned if you plan to grow vegetables in the raised bed. Just to err on the safe side, I would keep root vegetables such as potatoes, beets and carrots away from the sides of the bed and instead grow them in the center of the bed. Those vegetables that grow on the plants themselves (corn, peppers, tomatoes, etc.) should be just fine anywhere you plant them. Lettuces and other leafy crops should probably be grown towards the center of the bed as well. Yes, a soaker hose goes on top of the soil. Most veggies will grow best in at least 12 inches of soil. Your 8 inch deep bed will work if your don't overcrowd the plants. This way the roots can grow horizontally and still have enough room. If you have the opportunity, though, I'd suggest putting up another row of lumber so the bed is at least 12 inches deep. The soil will remain cooler during the summer months and you won't have to water as often. Best wishes with your raised bed garden!

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