Preparing garden beds part 2: raised beds

Foodscaping Utah’s ‘Benefits of Raised Beds’ class handout: Raised Bed Vegetable Gardening-Foodscaping Utah

Online class ‘Benefits of Raised Beds’ June 4th, 6:00-7:30pm taught by John (Foodscaping Utah) for USU Extension.

Raised beds have many advantages: they prevent soil compaction, alleviate some weed pressure, and require less bending over. Their soil also warms more quickly in the spring, which allows for earlier planting. But, most importantly, they provide excellent drainage. When drainage is poor, raised beds are the way to go. In our view, the advantages out weigh the disadvantages, but the main disadvantage is that the tend to require more irrigation because the drainage is so good. Raised beds can be built by simply mounding native soil mixed with compost (60/40 soil/compost or up to 50/50). If you are creating rows, make them 3 to 4 feet wide and dig the sides down to create paths. Of course, you can also construct walls for your raised beds with wood, brick, rock, etc. 

We usually build our raised beds out of 2x redwood lumber. Redwood is expensive, but it lasts a long time and looks great in our foodscape. Cedar has similar qualities if available. Pine or fir can also be used and is much less expensive. Recently redwood has been harder to come by, so for the last few beds we have build we used fir. We build our beds 8 to 15 inches tall, with 12 inches being our standard. Our first redwood bed used 8ft long 2x8s and was a more elaborate U-shaped design with two levels. Our recent installation uses 10ft long 2x12s to make a simpler 4×10 bed with six inch benches on each side:

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Here’s a materials list for the 10’x4’ bed with 6” bench on both sides:

  • Three 2×12 10ft -one cut in half to make two 5ft
  • Two 2×6 10ft for benches
  • One 4×4 8ft cut in six lengths for 16” pieces to set the benches on and to form feet
  • One box of 3” star flat-head deck screws
  • 1.5 yards soil/compost = 40sqft at 12” depth

To see how we built the above rectangle bed, see our Foodscaping our frontyard video, starting around 1:15. For more information on raised bed construction see USU Extension’s video. To fill our raised beds, we either use a 50/50 soil-compost mix, or when we have time to plan ahead we use a technique called sheet mulching, aka lasagna gardening. When building over lawn, we start by mowing the lawn as low as possible, soaking it and covering it with a soaked layer of cardboard. Then, you basically build layers up the same way you make compost. You alternate layers of ‘green’ materials (grass clippings, kitchen fruit/vegetable scraps, coffee grounds, etc) and ‘brown’ materials (brown leaves, straw, sawdust, etc). We put the food scraps toward the bottom (to eliminate odor and avoid attracting animals), then add alternating layer of leaves and coffee grounds, and a sprinkle of Azomite organic trace minerals. We usually mix in a layer of finished compost in the middle and always top it off with finished compost. Many lasagna gardeners top with weed-free straw. If you have weed-free topsoil you can also add it in layers.

The great thing about brown leaves and coffee grounds is you can typically get both of them for free. In the fall we not only use leaves from our own trees, but we also ask our neighbors for the bagged leaves that they were planning to dispose of. They are always more than happy to let us take them. Meanwhile, in the fall we collect spent coffee grounds from local coffee shops. Some shops have bagged coffee grounds ready for gardeners to pick up at any time and others were more than happy to fill five gallon buckets that we left with them.

Beds can be filled with the lasagna method any time of year, but fall is the ideal time. We like build and fill our beds in the fall for the easy access to leaves and so they benefit from winter moisture and time to break down. In the spring, if you top your lasagna garden with a thicker layer (4-6 inches) of compost or a topsoil/compost mix, you can plant in them right away! If you do not have access to loads of organic matter or the time to gather them, very successful beds can be made simply mixing your native topsoil and compost 50/50, which is what we typically do in the spring or when we want to get the bed built fast.

7 thoughts on “Preparing garden beds part 2: raised beds

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    1. You should totally build a raised bed over your lawn! Our raised beds have all gone right on top of existing lawn. The lasagna method combined with the cardboard will smoother the grass. I’d make sure to mow the grass low, soak the grass and the cardboard, and overlap the cardboard. Then you only have to build up 4 inches or so and it’ll be enough to eliminate the grass underneath. I’d recommend 8 inches or more though for super happy vegetables. We avoid tilling because it is ineffective on our Kentucky Blue Grass, which has rhizomes (it spreads quickly and easily under ground). Tilling also brings up dormant weed seeds.

  1. Just put my first raised bed frame together, went with pressure treated wood to save money. Bought 6 pieces of 12′ long 2×12 and had lumber yard cut off 4′ on each, then 6 pieces of4x4 8′ posts cut in half for the corners. This should give me enough for 3 4′ x 8′ raised beds with posts to put wire mesh on to keep out the rascally rabbits. One note darn heavy when all together so build near or at final location.

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