You want to fill an area of 15x12 feet x 18 inches deep How much dirt will it take?
This question is about a cubed area. First convert the inches to feet--18 inches is 1.5 feet. Then multiply all three numbers by each other. 15*12*1.5 is 270. You will need 270 cubed feet of dirt to fill the area.
Asparagus should be planted about 6 inches deep. Dig a trench, place the asparagus crowns in the trench, cover with 2 inches of dirt. As the spears poke through the soil, cover them again with dirt. Do this until the trench is completely filled back in. You will be rewarded with mouthwatering spears the following year.