What should be added to garden soil to loosen it up?

I mix the sand/dirt in my yard with cow manure that comes bagged and I add a little miracle grow. You can also get a sample of your dirt and send it to the lab through any home improvement store to see what your dirt is lacking.

I have the same problem with my backyard for wanting to put in a lawn. Try some Gypsom (spelling i'm not sure on) - then mix it all together, make sure there is also some potting mix in there coz that will help with keeping the moisture in - chicken poop does a great job too!

Try Adding some mulch ,compost maybe even some sand it sounds like your working with clay .The roots of your planting will never penetrate .Save your grass clipping and leaves in the corner of the yard or some out of the way area .I'll just put them in lawn bags with some water so that it will rot .As it does begin to rot it will start to smell like garbage that's why you'll want it out of the way .However when you turn the soil in the spring the next season just mix this compost into the soil and after a couple of seasons doing that you'll have great soil for planting .