depth of a raised bed

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Permalink Reply by Courtney Ostaff on January 3, 2009 at 8:04pm

See also:
http://mygarden.rhs.org.uk/forums/p/15153/15153.aspx
http://ceamador.ucdavis.edu/files/946.pdf


The easy answer is that the beds should be deep enough for the roots of the plants you plan to put in the beds. Trees, obviously, have very deep roots. Annuals have shallow roots. Personally, I like a raised bed at least 1 foot deep, and preferably 2 to 3 feet. I'm tall,and so it's easy to have something near waist height. Plus, I'd rather have too deep a raised bed than too shallow. Lee Valley makes some great kits for raised beds. You could put ground cover on the bottom of the raised bed if you are so inclined - that would allow the soil to drain properly, but still retain the dirt. I have extremely clay soil, so I have no need of that. I have read that sandy soil drains too fast for optimum plant growth, because all the nutrients wash away. I use 1/5 soil, 1/5 compost, 1/5 manure, 1/5 sand (remember, we have lots of clay), 1/5 peat moss in my beds, with excellent results. You can use plank wood: cedar is ideal, if expensive. A hardwood would be your next best bet, if you can get it: oak and so on. A third option is to use concrete patio squares in a frame. I have used small trees that we cut down, and cut the branches to all about 3 feet long, and sunk the ends in the soil to make a pleasing frame. My mother tended to not use any sides, and just mound the soil.

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Permalink Reply by Penelope on January 5, 2009 at 8:09am

Consider making the width of the raised bed 4 or maybe 5 feet tops so that the bed is easily managed from all sides and to preclude walking on the bed's soil to prevent compacting.

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Permalink Reply by Courtney Ostaff on January 3, 2009 at 8:04pm

See also:
http://mygarden.rhs.org.uk/forums/p/15153/15153.aspx
http://ceamador.ucdavis.edu/files/946.pdf


The easy answer is that the beds should be deep enough for the roots of the plants you plan to put in the beds. Trees, obviously, have very deep roots. Annuals have shallow roots. Personally, I like a raised bed at least 1 foot deep, and preferably 2 to 3 feet. I'm tall,and so it's easy to have something near waist height. Plus, I'd rather have too deep a raised bed than too shallow. Lee Valley makes some great kits for raised beds. You could put ground cover on the bottom of the raised bed if you are so inclined - that would allow the soil to drain properly, but still retain the dirt. I have extremely clay soil, so I have no need of that. I have read that sandy soil drains too fast for optimum plant growth, because all the nutrients wash away. I use 1/5 soil, 1/5 compost, 1/5 manure, 1/5 sand (remember, we have lots of clay), 1/5 peat moss in my beds, with excellent results. You can use plank wood: cedar is ideal, if expensive. A hardwood would be your next best bet, if you can get it: oak and so on. A third option is to use concrete patio squares in a frame. I have used small trees that we cut down, and cut the branches to all about 3 feet long, and sunk the ends in the soil to make a pleasing frame. My mother tended to not use any sides, and just mound the soil.

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Permalink Reply by Maya on January 4, 2009 at 9:15pm

Sandy loam, as is prevalent throughout much of the northeastern US, is excellent for growing and drainage, though you will probably want to add organic matter in the form of good compost. You can dump a foot or more of compost right on top of the existing soil and it will kill most of the weeds underneath. Anything that works its way through is weak enough to just pull. If you want to build sides, 2 x 8s with carriage screws and washers are the easiest. You can use KDS or any other soft, dimensioned lumber from your local lumberyard. Both cedar and hardwoods are going to be very expensive. Rough hemlock direct from a sawmill will not rot as fast as your softwood dimensioned lumber (mine's going on ten years and rotting at the corners), but a little faster than untreated cedar, and is an affordable option.

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Permalink Reply by Penelope on January 7, 2009 at 10:33am

Strawberries love sandy soil.

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Permalink Reply by Kyle Gassman on January 11, 2009 at 4:45pm

I've got really sandy soil also. And raised beds seemed to be the way to go/to grow. I've put these six foot in diameter plastic drainage tiles to use as my raised beds. They are two feet tall which is a comfortable height to work at. I salvaged these from a construction site. As soon as I saw these cut off pieces I knew what I wanted to do with them.
I filled them with a 50% mix of imported compost and topsoil from a local compost facility.
So keep your eyes open for items that could be reused as a raised bed. Check out the rest of my photos on my page.

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Permalink Reply by James on January 11, 2009 at 7:01pm

Thanks Kyle.

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Permalink Reply by Snowshiva on January 25, 2009 at 10:44am

Hmmm, Well after looking into it I would like to retract my words.... Do not use treated wood. The pressure treated wood is forced with cyanide to prevent rot and pest damage which can leach into the soil... not good (although some reports said that the amounts would not be harmful, I personally would not like to take the chance).
I will now hang my head in shame.

On another note Cedar seems to be a great wood to use as it will last for a very long time, and with some non-rusting carriage bolts it can be taken apart for storage or moving location, plus it looks really nice too!

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Permalink Reply by Martha Hill on January 26, 2009 at 11:23am

I am in NE Texas and we have deep sand !! But you would be surprised at what you can grow with just the addition of composted manure !! That is what we do and our garden makes more than we, and all our neighbors can eat !! Because the soil is sand, it doesn`t mean that its not fertile !! You might want to have it tested before you do raised beds !! Worst thing about sand is it dries out quickly !! You might need to water a bit more frequently in summer !! Mulch will help that !!

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Permalink Reply by Debra Donohoe on September 5, 2009 at 11:30pm

Hi, I have to have raised beds because of our Spanaway Spuds! All rocks. If you can dig out any grass below ther roots. If not put a weed barrier down. The grass will grow up if you don't. Think about using cinder blocks.Don't use treated wood it will leach into your soil and into your vegetables and or fruit. I've heard of using cardboard,espically in lasagne gardening. Let me know if this works.
Debbie Donohoe

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Permalink Reply by Clarence on September 7, 2009 at 7:07am

Cardboard works well at smothering grass, weeds, etc when starting a new bed. This year is my first year at trying this method and for the most part it has worked very well.

I can also report on the the cement block raised bed that I made this year. It started this season more as a compost bin which I covered with soil once it neared the top row of blocks. It then became the home of some winter squash plants which have done very well. The compost and soil have settled so I will be adding more of both once the squash vines are done.

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