Creating Color in a Rock Garden

I would like to begin this post by bragging on my family's ability to garden.  My great-grandmother grew fresh vegetables until she was ninety.  My Grandfather was a farmer.  Both of my grandmother's have beautiful flower gardens.  And, despite what she may say, my mother has a beautiful yard full of beautiful gardens.  I like flowers.  I love herbs.  I am grateful to my beautiful, hearty knock-out roses that have beaten the odds and thrived in my backyard.  That being said, we recently grew tired of our crazy out-of-control yard, so we overhauled our front garden area.  When we bought the house, it was a lovely manicured area full of high-maintenance shrubs and things.  (I know they have names, but I am a little plant-ignorant.) We ripped out all but a few plants and "planted" rocks in their place.  We love it!  After a week, we decided it needed some color.  Remembering that we have neither the time nor the talent for gardening, we decided on mums, marigolds, and potted herbs.  I turned wrought-iron center pieces used in our wedding reception into planters using cheese cloth to keep in the dirt.  I hope it doesn't all wash away after the first rain.  In the mean time, it has the potential to be just the pop of color we want.