Double digging a garden bed is the first step toward having a very productive garden. If you want to grow root vegetables, double digging is especially helpful because it creates a deep area of loose, friable soil. Most (if not all) plants you might be thinking of planting will benefit from this treatment. It is hard work, however, and it is also time consuming. Set aside a day or even a couple of days if your garden is very large. Take frequent breaks and make sure to stay hydrated as you work.
Test your soil at your intended garden site before beginning. Home soil test kits are available from garden centers, but your county extension office offers a more comprehensive and accurate test at a comparable cost. If the results are not clear to you, you can speak to someone at the extension office who can help explain what they mean and direct you toward any soil amendments you need to purchase. Agricultural lime raises the pH level of the soil, while sulfur lowers it. Other amendments may also be necessary, depending on your soil's level of various nutrients.
Dig a trench across your garden that is 1-foot wide by 1-foot deep. Move the soil from that trench into the wheelbarrow as you dig.
Plunge the pitchfork straight down into the bottom of your trench and rock it back and forth to loosen the soil. Continue in this manner all the way down the length of the trench.
Dig a second 1-foot wide by 1-food deep trench, right next to the first. Move the soil from that trench into the first trench as you dig. Loosen and fluff the soil at the bottom with the pitchfork once more.
Repeat the trench-digging and soil-moving process until your entire garden has been dug. Place the soil in the wheelbarrow from the first trench in the last trench that you dig.
Mix compost into the finished soil in a 1:1 ratio across all trenches. Add any other soil amendments recommended by your soil test at this time as well. Consult your county extension office for appropriate application amounts.