Welcome to Garden Month! If you read Monday's post, you know that the best soil amendments increase water- and nutrient-holding capacity and improve aeration and water infiltration. However, you can improve the aeration without adding a single amendment to your garden! Double digging improves aeration and breaks up the soil so roots are able to grow freely. It is inexpensive and doesn't require anything with a motor.
If you have amendments that you want to add to the soil, they go in after you've dug the first foot and sifted the second foot of depth. So the amendments end up being about a foot deep in your garden bed.
Vacant soil like this is a haven for weeds, so if you don't plan on planting anything right away, keep the soil covered. A black tarp that doesn't let any light in is one option (if you let light in, you're just making a nice, toasty greenhouse for weeds). If you don't plan on planting anytime soon, pieces of cardboard covered with leaf mold or compost is another option - the cardboard prevents weed growth, but also decomposes to create more organic matter.
Soil amendments: check! Double digging: check! I think we're just about ready to get down and dirty with some seedlings!