I'm not sure what "sterilizing" Marilyn is talking about - but I "sterilized" year before last by taking all my plants out of my front bed in the beginning of the summer. Then I covered the bed with black plastic so when it got really hot, the seeds/stuff "cooked" over the summer. Yes, our front yard looked sorta like the "Clampets" but we don't live in a fussy neighborhood, so it was OK
This method is called solarizing and is a safe way to kill weeds/seeds. If you want to plant again in the same spot, you really can't use any kind of chemicals. Plus, I'm a "green grower" and don't use any kind of chemicals at all in my yard. We put in a rock bed, rather than flowers, so that we don't have to use extra water to keep them alive.
I want to put in a 12X5 garden in my back yard. I don't get tons of sunlight, but I think I could grow a few vegetables. We will have to put in a raised bed - using landscape timbers and then have garden soil hauled in. We only have about 3-4" of soil in our back yard and then it is caliche (sp) rock. I'll probably get the guys that did our yardwork this fall to do it, either in late Jan or early Feb.