Annual flower seeds should be planted in northern Illinois as early as possible, per the package's instructions pertaining to frost-hardiness, to ensure enough time to grow through the season. Perennial seeds can be planted into mid-to-late summer to give the plant enough time to establish itself before the fall frost. Perennial seeds are an excellent way to stretch your gardening budget, as the plants will return year-after-year.
About this Author
Bobbi Keffer attended Kent State University, studying education but soon found her true love to be in the garden. She prides herself on her frugal skills, re-using, recycling, and re-inventing her whimsical style in her home and garden.