Constructing a Raised Bed Garden

by Juan Wilson

© 1994 The Gobbler: Winter Thaw

 

 

Everybody has a different approach to building this kind of thing, so let's start with understanding that nothing is sacred when it comes to building a raised bed garden. The example I'm going to share with you is my experience the first time building a raised bed for an intensive "square foot" garden. There have been some problems, but it seems to have worked out fairly well.

The material you use to raise the earth in a raised bed needs careful selection. Wood and stone are candidates for edge material. But contamination by chemicals must be considered. Therefore, treated wood like railroad ties or decking material is out. The tars and chemicals from these woods are poisonous and easily leach into the soil. If using brick, even mortar rubble might be considered a problem.

We chose to use fresh cut green lumber from a nearby Amish sawmill. There are several in the area, and they are all priced considerably lower than Grossman's or other commercial lumber yards for the same volume of wood. We bought 1"x10"x8' lumber for about 1/3 the cost of a commercial yard. We needed 36 boards.

We strongly suggest you lay out your garden with a scaled drawing. One quarter inch equals a foot is convenient if all you have is a ruler, pencil and letter size paper. We were planning "square foot" gardening, so we wanted earth boxes that could be flexibly divided in one-foot-square modules. We decided to use 4 foot by 8 foot boxes. This would require little cutting of our 8 foot boards and it would be narrow enough to be accessible. At the north end of the garden we placed narrower boxes, 2 foot by 8 foot, for the climbers (tomatoes, beans etc). Once we decided on a layout we cut the boards and simply laid them out on the ground where they would be made into boxes. When spacing the boxes be sure to leave wide enough aisles. We suggest 3 to 4 foot minimum.

When positioned, we hammered the boards together with galvanized nails, and leveled the boxes a bit. There will be a tendency, once loaded, for the long sides of the boxes to bulge. This can be countered by pounding a peg into the ground on either side of the box, or nailing a strip of wood underneath and between the two long sides to act as a strap.

We used heavy galvanized tubes seven feet long for the corners and gate opening of our garden. Use a post hole digger to get them in. Lightweight, bent steel garden posts are cheap, but bend a lot and rust quickly. We used them only between the tubes, where there was little stress.

We hooked two fifty-foot rolls of galvanized chicken wire to the outside of the poles. When the wire was in place we edged the outside of the garden fencing with more 1"x 10"x 8' boards and piled earth against them. This was to discourage animals from burrowing under the wire fencing. We then stapled the chicken wire to the inside of the boards, creating an earth and wire fortress.

Around the outside of the boxes we used a chainsaw to make quarter inch deep nicks every one foot on center. This was so that later we could easily find the square foot modules for garden planning. String could be stretched between the nicks, or eyeball seeding and watering could be done, using the nicks as guides.

We filled the planting boxes with a mix of some earth from the aisle with composted manure, wood ashes, and lime. For the climbing plants we constructed a frame cut from similar branched saplings pounded into the ground. Cross members sit in the crotch of the branched vertical saplings over each box. String, for climbers, was tied from the cross members to nails in the planting box frame below. We had spaces in the north corners of our garden. In one we placed a work table and folding chair, and in the other a galvanized welded garbage can we could fill with a hose (or with rain) for our ever thirsty watering can. Incidentally, the first summer we had no invaders into our garden, but last year something jumped or climbed the wire. We may have to go with an electric strand, or move our doghouse over to the garden as a defense.


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