Building a Raised Bed

>> Sunday, January 20, 2008

Here is a really easy project that adds a bit of formality to your garden and is actually healthier for your plants and easier for you to access them.

Several of my vegetable beds are raised beds. I built these because, one, they clearly define a space I set aside just for vegetables. Two, the soil in these beds never get stepped on, this is very important because compacting the soil is not good for any plant. Last reason is because the soil here in Utah is clay. Darn the luck. And being clay, it is difficult to work in, needs a lot of amending and it is a little more alkaline than I would like to garden in.

With raised beds,

I can add good quality soil and mix it easily with compost and other amendments,
I am not tempted to walk on it because of the sides
and the soil is always fluffy and easy to work with (arable).

Alkalinity, just as a side note, locks up the nutrients and prevents plant roots from having access to them. The cure for this is iron chelate (pronounced key-late). It is a bit expensive but there is a huge market for it here in Utah. Before you go running out and buying this stuff, you need to know that you only have to use a small amount and if you use too much it will burn the plant’s leaves. As always, it is best to get a soil test before using any soil amendment.

Building these is pretty straight forward unless you want to get fancy and start making hexagons and octagons. Typically they are four sided and stand about two board widths tall.

Materials. If you want to use wood, get cedar or redwood and don’t use treated wood. These two woods stand up a long time against the wet soil typically found in gardens without rotting away. Pine is one of the worst materials, it can be used but plan on replacing it next year. Concrete or cinder blocks, bricks, or even bales of hay can be used. The thing about concrete blocks is that the lime content tends to leak into the soil. Lime is one of reasons our soil here is alkaline, so this is not always a good choice of material.

About pressure-treated wood, some people say that the treatment (which makes the wood rot and insect resistant) won’t bother your edible plants, but I figure why take the chance. We already have enough to worry about with our food chain, I am not going to add another possibility of contamination.

This bed, pictured here, is one of four, built of four 2”x6”x8’ cedar, cut in half and stacked two high. They are going through their fourth winter. I don’t plan on replacing these for another two to four years. Although I have heard reports of them lasting even longer. If they do, I will consider myself lucky. They cost me about fifteen dollars each for lumber and screws. Be sure to use galvanized so they don’t get rusty. This bed has eight pepper plants and one small lilac bush.

For the supports, I used two by fours but you could easily use one by twos. I cut the other end into a point so they could be hammered into the ground. Also, I placed about ten sheets of newspaper at the bottom of each to cover the grass growing there. It helps keep most of the grass out but I still occasionally have to pull some grass. I don’t consider it a major problem.

You can build them taller so you don’t have to bend over as far to get into them, but consider the extra amount of soil you have to add and the added pressure from all of that weight on the sides as they get taller. You can build a seat around all four sides or just one side, whatever suits your needs.

You can place PVC pipes on the outside, or inside before filling the beds up with soil, to hold hoops for row covers and for trellises. I’m planning on doing this within the next few months. Cut a length of 1" diameter PVC pipe just shorter than the height of the bed frame and attach it with 'U' screws to the bed sides. You then place the ends of a smaller diameter PVC pipe inside the larger pipe for support.

You can also build a cold frame the same size as the bed and attach this to the bed to help harden off transplants and to extend your growing season.

These boxes are pretty versatile.

To make them easily accessible from all sides they should be built no wider than 3’ to 4’. They can be about as long as you have space for them, but you do want to be able to walk around them so its impractical to make them too long. I had built two, many years ago, that were each eight feet long. Those worked pretty well because I didn’t have to walk real far to get around them.

This bed I built last year is 4’ by 14.5’ but it is up against the deck and I won’t have to access it from the back side. I put larger plants, Bee Balm and Phlox, along the back, to help camouflage the deck from the yard, and then shorter perennials up front.

Each fall, after pulling out all of the plants and tilling the soil with my pitchfork, I pile leaves and grass clippings on top, about 6” to 8” deep and let them breakdown over winter. In spring, I’ll pile about 3” to 5” composted steer manure on top and then till that in with my pitchfork. I have always had healthy fruitful crops this way.

If you want your beds to stand up to winter and remain easily workable then raised beds are the way to go.

Good gardening!


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