http://www.sosostris.com/wp-content/uploads/2013/03/HNI_00962.jpg
This is hands-down the most efficient method (you can replace the fertilizer bag in the center with a jacob's ladder). Plant them like this and leave an open space on all sides, then water with a golden can (or if you don't have it yet, water all flowers including the jacob's ladder if you're using that in lieu of a fertilizer bag).