This is one of the most useful tools we have on the farm. It's called a rolling dibbler and we found the plans at
High Mowing Seeds in their newsletter archives. It creates little dimples precisely spaced in a planting bed. We then put a plant or bulb in each dibble, every other one, every other row, etc., depending on how we want to space that particular planting. It saves time and also places plants evenly spaced which gives each plant the same amount of growing space.