How to Make a Raised Bed
(This article is taken from a the series ‘Raised Bed Gardens’ by Gardening-coaches.com and is used with permission)
Making a raised bed garden isn’t rocket science and it doesn’t require superhuman effort. It is fairly simple, low cost, but requires lots of work the first time you do it. The preliminary work to create a deep, prepared bed does pay off in succeeding years. You have healthier soil, healthier plants and a more productive garden.
Let’s look at the steps…
1) Loosening and cleaning up the soil.
The first order of business is to break up the (normally) compacted earth. Your best bet is to use a garden fork to break up the compacted soil and any ‘hard pan’ that may be present. The idea is not to turn the soil over or totally stir up the soil, but rather to break up the compacted area you want to give to your roots. Remove any weeds during this step.
Add any soil amendments to the broken up surface of the soil, and fork the ground up again. As before, the idea is to not turn cover the soil, but simple let the amendments to filter through the loosened dirt. Soil conditioners that are mixed into the soil are called amendments; materials that go on top of the soil are mulches.
Your job is to create a gradual change from enriched soil down to the subsoil. A sudden change in soil composition will form a barrier to water movement in the ground. Biological agents in the soil will continue this process in the future.
The soil you have to work with dictates the amendments. Heavy clay or loose sandy soils require more amendment than loam, but all soils benefit from organic amendments. Organic matter in the soil acts as a sponge that holds water, air and dissolved nutrients, ready to be taken up by the plants.
Note: Steer manure is classified as a soil amendment, not as a fertilizer. To be a legal ‘fertilizer’, there needs to be a minimum guaranteed amount of nitrogen in the product, and steer manure fails the test. It is a good soil conditioner, though.
2) Double-digging
(Note: here is a point on which our Master Gardener instructor and I, plus most of the gardeners in the class, disagreed. Dr. Downer was not convinced it was worthwhile, but his viewpoint was perhaps for larger scale agriculture while ours was the home garden. My opinion is backed up by the Peace Corps, but take my advice with a grain of salt… )
Double digging is discussed in this video,
Home vegetable Gardening, Part 1, starting at about minute 19…
Double digging is the most important step for true deep bed prep.
The idea is to remove a shovel-depth of soil and set it aside, add amendments to the bottom of the resulting hole, and fork the amendments into the exposed subsoil as we talked about above. Go as deep as reasonable. Moist soil of course works easiest, and you may need to re-moisten the area and wait for the water to soak in. Push and pull back on the handle of your fork as you go down to break up and loosen the soil. Move the fork or spade back a few inches and repeat until your trench is complete.
In a narrow bed, move from side to side, then back a few inches and do an entire bed in one pass. On wider beds, it may be easier to make one long, narrow trench, then make another pass next to it, and move soil from side to side as you double dig. In either case, the idea is to move the top layer of earth, go down another shovel depth, then add the top of the next section to what you just broke up.
Replace the soil you removed previously and mix in amendments as you go, then fork this upper layer up. You now have a loosened area 16″ to 24″ deep with passages through the soil for the exchange of air and water.
This deeper cultivation will promote deeper moisture and root penetration. In really tough ground, you may not be able to go as deep as you like, but the next time you work up the soil, it will have been softened by the probing plant roots.
The final step is to rake out the resulting bed, moisten the soil, and let it rest for a day while the soil moisture stabilizes. You can now add your drip system and cover the soil with a weed prohibiting layer of organic mulch.
To read this article in its original form, please visit the Camarillo Community Gardens
Vegetable Gardening 101 pages.