When you till you are only aggetating maybe the top foot to 1 1/2' of the soil. Take a 1" diameter steel pipe and physically force it into the ground at intervals of 12" on center, to anout3 feet. Do this after saturating your flower bed with water, that will make the pipe penetrate the soil easier. The holes made by this, will allow a better drainage for the rest of the bed as well. When you have the pipe at the depth make sure you move it in circles so as to break up the soil and the clay areas. -Birdy