Fall is the optimum time to plant spring-blooming bulbs and new perennials. Gardeners can plant pansies in the fall and in most climates enjoy their bloom again in the spring. The window for fall planting ends six weeks before the local date for hard frost, generally in September or October.
To extend the gardening season, plant both fall- and spring-blooming flowers in autumn. Asters are perennials that are widely available in nurseries during fall, when they bloom in shades of blue and purple. Cut the plants down to 2 inches above the ground after the first killing frost for healthy growth the following year. Mums are hardy flowering plants often associated with fall. They actually bloom from late summer until the first frost and come in a wide range of color and petal choices. Plant perennial, reliable and colorful crocus and tulip bulbs in the fall for early spring bloom.
Irises are perennials that bloom in early spring and summer. Because their roots must be well-established before they can bloom, fall is the ideal planting time. Cut iris back to the ground after blooming and split and transplant bulbs every three or four years, keeping the tuber tops partially exposed.