depth of a raised bed

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Permalink Reply by Snowshiva on January 1, 2009 at 1:23pm

Yep, you will need real wood, not any type of partical board like MDF as they will swell and break apart. You can get tanalised soft woods that have been treated with chemicals to prevent rot. I think these work out cheaper than hardwoods.

But I really don't know if the treatment in the woods would be advisable for food crops, this is something I want to know myself.

I guess the depth of the dirt is dependant upon the crops you want to grow. I believe a foot deep is pretty good going for most things.

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Permalink Reply by Kate E on September 6, 2009 at 11:52am

Salt treated wood contains arsenic, so is not a good choice...our water has much higher than normal arsenic levels from sawdust resulting from our recent construction boom....not good

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Permalink Reply by Sarina on January 1, 2009 at 4:14pm

Don`t be too hasty in disregarding your sandy soil. If you`re intend on growing some good carrots, I suggest mixxing 2/3 of it with some other good compost. Carrots like it sandy/gritty.

Sarina

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Permalink Reply by Sarina on January 1, 2009 at 4:18pm

Raised beds can be assembled straight on top of existing soil, even grass. I would use a layer of old cardboard as a weed surpressant barrier and wet it well before topfilling with good compost. The cardboard will eventually bio-degrade.

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Permalink Reply by James on January 1, 2009 at 4:21pm

Thanks Sarina. Very helpful.

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Permalink Reply by Sarina on January 1, 2009 at 4:27pm

Any time,
nice to be of help

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Permalink Reply by Kathleen on June 11, 2009 at 7:56pm

If you use cardboard on the bottom of the bed, after they degrade wouldn't you get weeds then or would the weight of the dirt keep them at bay?

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Permalink Reply by Linda on January 1, 2009 at 4:22pm

I'd advise you to put your bed direct onto your soil unless it is contaminated. Importing soil that is a good loam and has structure will benefit in the end from being on a sandy base because the drainage will be excellent. If you put in a barrier you risk causing poor drainage. So far as depth is concerned I've seen high beds that suited people who didn't want to bend so built them up to about 3 feet. Mine are raised about 18 inches over clay and this seems to suit both cultivation and growing carrots, parsnips, potatoes etc which are a good measure of depth required. Avoid using treated wood. We got plain, untreated 12" x 4" planks and painted them with an organic paint to keep them from soaking up moisture. That was 4 years ago and they are still going strong.

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Permalink Reply by Sarina on January 1, 2009 at 4:23pm

Here in Britain, most people use untreated railway sleepers as wood surround for their raised beds, often also use them as double hight, 2 sleepers high, stacked up together, as I have often seen used in allotments. These woods can last good 40 years without treatments.

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Permalink Reply by Clarence on January 2, 2009 at 7:46am

Jams,

Depth of raised beds can very from a few inches or feet what ever will work best for you.... most that I have seen are at least the width of two 2 x 6's (or just under 12''). As I mature I am starting to look at those raised beds that are at lawn chair height....

I have put 1/2'' hardware cloth on the bottom of some of my raised beds to keep vegetable damaging rodents from burrowing up into the raised bed i.e. voles, gophers, chipmunks... of course if a chipmunk can't come up from the bottom they will just go over the top... sigh.

As far as the kind of wood to use.... I would not use any of the pressure treated wood because of the arsenic that leaches out of it. Some studies show that the arsenic only migrates a few inches away from the wood but why take the chance if you don't have too? Cedar is costly but last for years and years, just plain untreated pine will last for a few years as well.

I have straw bale raised beds that are two and three years old (not real pretty or popular with the wife). They started out as hot beds in the early spring to start plants in. I cover them with old door wall glass to make mini green houses... most times they work well but this last year I put my tomato flats in too early and cooked the poor things.... Then I put soil on top of the cold compost and use them like any raised bed.... the straw bales last longer if I cover top of the bale with wood planks which also makes sitting on them to work more comfortable. Once they are too far gone, I either use the straw for mulch or fodder for the compost bins.

I am thinking of using some cement blocks that were given to me last summer. Shop at home is one of my mottos. Why buy something when there is already something on hand that will work? (I will have to keep an eye on the ph as cement tends to neutralize acid). I wish I had enough field stone to make raised beds with, we terraced the front yard last year to make it usable for gardening, which depleted the stone I had lying around. We like the look of the stone but so do the chipmunks... sigh. ~:>

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Permalink Reply by Charlie Radoslovich on January 2, 2009 at 10:07am

Happy New Year JD,

How exciting! Looks like a fair amount of people replied, but here are my two dandies. The best wood that won't rot is Black Locust (invasive species, but some sawyers have it). Pallet wood is free, but only lasts for six years max. Certified organic compost would be the best bet for your needs. Good luck in 2009!
Happy growing

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Permalink Reply by James on January 2, 2009 at 2:36pm

Thanks Charlie.

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