Q: Is double-digging a good idea?

A:  "Double-digging", the practice of removing topsoil ( the first dig), loosening the subsoil and digging in soil amemdments (the second dig), and replacing the topsoil, used to be very common, especially for vegetable gardens. The modern consesus is that it is generally not a good idea because it tends to disrupt the natural layering and organisms in the soil, it's too easy to mix the topsoil and subsoil, it can lead to greater erosion, and it can release stored carbon into the air. It's also a lot of work! However, if the soil is badly compacted in the only sunny area you have for a kitchen garden, and you do this carefully, it can be a help, especially if you mulch the soil afterwards. For most beds, and even for vegetable ones, just adding compost regularly for the soil critters to pull down and the roots to use, gently aerating the soil with a garden fork, and watering regularly (making sure not to push out the air by walking on the wet soil) should keep most beds (and your back) in decent shape. And of course, raised beds are always an option.