Plants are popular for a reason. For standbys such as petunias and marigolds it's because they are easy to grow, they bloom reliably all summer, they are available in a wide range of colors and flower forms, and they have few insect and disease problems.
See the ISU Extension & Outreach Yard & Garden news release from February 22, 2012 for more information about selecting and growing petunias, and the Yard & Garden news release from March 1, 2012 to learn when and how to start marigolds and when to plant them outside.
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