Okay, #gardening Mastdodon folks... I need help. I have an area that runs all along a fence line where they ripped up the sod to to fix a retaining wall on the other side of the fence. After they put my fence back up, I asked them not to replace the sod in a 2 foot strip all along the fence so I could turn it into gardens, BUT it is really hard packed dirt -- too hard to even dig into without *great* difficulty. What's the easiest and least expensive way to turn hard dirt into a good garden bed? And if I save up to buy dirt this fall, do I need to do something to the hard dirt first, or can I just put the new dirt on top?