Filling an area with components/objects

This is likely a novice level question. The gentleman who introduced me to sketchup used to do this. I design landscape enhancements and use sketchup for this. What i would like to be able to do is fill an area with a chosen number of components that will go in even spaced. He was able to do this, then change the number or change the spacing, etc. The point is to quickly get the number of items into the area and adjust as needed without having to place each one at a time.