Every summer I plant a few annuals in the garden to create an accent or focal point in the landscape. A few impatiens here, a group of super petunias there; it doesn’t take much to create that extra interest. By this time of year any extra interest value is long gone, and it is time for them to go.
Years ago, I would pull them all up and lug them off to the compost pile. One year, in an enlightened moment, I realized that I was pulling up a rootball of some pretty nice potting soil with each and every plant. This was not just a waste of some of the best growing medium going, but it also made for some pretty heavy trips to the compost pile.
I now cut the annuals off at ground level and leave the rootball in the ground. The soil of a few dozen 4- or 6-inch size pots can make a nice contribution to the organic matter content of the garden.