Planting flowers in autumn accomplishes two gardening tasks: extending the blooming season of the garden and allowing spring flowers to get a good start before the ground freezes. October is a good target month for planting these types of flowers. Annuals and perennials, as well as bulbs, can be planted in October.
Annuals are flowers that must be replanted each year. Annuals that are planted in October can usually withstand the first frost and continue blooming into November as long as they are covered overnight when frost warnings are issued. Cover the flowers loosely with old sheets or shirts; don't use plastic because the potential for heat buildup under the plastic is high and could burn the foliage beneath if the plastic is not removed before the sun begins to heat it. Examples of annual flowers are pansies, snapdragons, asters, marigolds, petunias and zinnias. Buy flats of annuals in late summer for October planting.
Spring bulbs are planted during October to allow the roots to establish themselves before the hard frost and soil freezing. Examples of these flowers include varieties of lily, hyacinth and iris. Some bulbs can bloom in autumn and overwinter as long as they are cut back and covered before the frost. All bulb plants should be covered during winter with mulch or leaves to protect them from cold temperatures. Planting bulbs in blocks or groups using trenches or hills allows for easier care.
Perennials are plants that are planted once and bloom each year after if properly cared for. Perennials must be covered during frost warnings and over winter months. Use a loose cover of old sheets. Cut back the foliage and cover with mulch or leaves. Remove the cover after the last winter frost and allow the plants to resume. Examples of perennials to plant in October include chrysanthemums and mums. Butterfly and hummingbird gardens can use perennial varieties of aster, primrose and dianthus.
Foliage that overwinters can be planted in October. These bloom during the autumn, then go dormant through winter, and revive themselves to bloom again in early spring. This type of flower can withstand first frosts and temperatures under 50 degrees Fahrenheit. Flowering plants such as foxglove and bleeding heart are examples. There are both annual and perennial flowers in this category; the perennials will stop blooming during summer and resume again in autumn giving two blooms per year (autumn and spring).