Outdoor color during October is usually supplied by falling leaves, but plenty of flowers can give you color at ground level. Some of these will be holdovers from September, in season during October, too; others will just be coming into their own as October unfolds. Of these, some will persist into November or even later. Choose carefully, for a flower in season during October in one part of the country may not be in season somewhere else. Call your local extension office if you need advice.
Though most think of the crocus as a harbinger of spring, there are varieties that announce fall. Unlike their spring brothers, fall-blooming crocuses like cool, somewhat shady spots. You can grow them from seed, but will have to wait at least three years to see them fully developed. For less patient gardeners, buy corms and plant them 4 inches apart and about 4 inches deep. You can enjoy purple blooms in fall if you plant them in late August or early September.
There are many fall crocuses that bloom in early October, but you might want to plant several varieties to have crocuses blooming from September through November. Happily, crocuses self-multiply.
Speaking of crocuses, what many people call "autumn crocus" is actually colchicum. This is a plant that is a bit of a fake-out grower--that is, colchicum puts up hearty-looking foliage in spring, which might leave some thinking the plant will bloom soon. Instead, the foliage dies back.
In autumn, after you might have forgotten about the disappointing plant, it puts up stems. Distrustful gardeners might be surprised when, this time, the stems erupt in blooms reminiscent of crocuses.
Plant corms around the same time you would crocuses, but give these corms more room--about 9 inches between them--at a depth that puts the top of the corm 3 or 4 inches deep. Because the spring foliage will die back, you should plant the bulbs where other growth will mask the mess. The mess will be worth it in fall; the flowers are often scented.
You might know rudbeckia as black-eyed Susans or coneflower. They're hard to miss, growing up to 9 feet tall, depending on which kind you plant, with happy yellow flowers sporting prominent brown, black or green centers. These centers provide seed for birds after the petals have dropped.
Rudbeckia seem to have sunny natures and they do like the sun. "Goldsturm" is a popular variety that blooms through October, this Rudbeckia only growing up to 3 feet tall. "Autumn Sun" will also bloom in October, and this plant reaches about 6 feet. All types aren't particularly picky about soil.
Flowers in the viola family, depending on the kind, can stand up to sudden cool temperatures that sometimes come with October. Pansy, especially, can be relied on; you'll often see the plants put into beds in parking lots to liven things up as temperatures drop and days shorten.
They pansies do succeed in cheering up dreary nooks, putting out 2- to 3-inch flowers with lush colors and interesting markings. Pansies make good cut flowers. Another plus: the petals are edible.
A new variety of viola--Endurio Sky Blue Martien--will also grow as the weather gets colder. Indeed, it was chosen as the 2010 All-America cool-season flower. It produces true, blue flowers, which isn't common in nature, these flowers diminutive at only 1-inch wide, but blossoming in masses on the plant.
This viola begins blooming in October and continues on through the winter if your climate isn't too inhospitable.