Autumn into early winter (depending on where you live) is the peak time to plant spring-blooming bulbs, including tulips, daffodils, hyacinths, alliums, and crocuses. It's important to put them in the ground now because they need a long winter of beauty sleep to get ready for their spring coming-out party.
Up come spring bulbs, such as daffodils and crocus, followed by perennials, such as dianthus and garden phlox. When you plant early (in autumn), your perennials flourish faster in spring and summer.
Autumn is a great season for annuals, low-maintenance perennials and evergreen shrubs to shine. In fact, some of the most popular flowers, like colorful mums, roses, dahlias, purple pansies and yes, even bright yellow sunflowers, all bloom around September and October.
Fall is Good for Root Growth
Warm soil temperatures encourage root growth – more so than in the spring when the soil is still warming up. Plus, with the shorter days and cooler air temperatures, plants spend less energy on growing foliage and flowers and more on building a strong root system in preparation for winter.
Although each plant's needs may vary and some will be more winter-hardy than others, in general about a month before the last fall frost is sufficient in giving the plant enough time to establish itself and take root.
Mid- to late-August is often an excellent time to plant fall flowers, as long as the weather isn't still so hot that the plants will suffer heat stress. But don't wait too late to plant, or you'll have a very short window to enjoy your flowers. Check the growing requirements for each plant.
October is the season to plant spring-blooming bulbs, wildflowers, and many standard gardening favorites. The flowers that don't blossom this winter can spend the cold season in the ground, strengthening their root systems in preparation for a springtime bloom.
Asters. These beautiful fall-flowering perennials are a lovely companion planting to chrysanthemums, the other stars of the autumn garden. Give asters full sun, and water to get them established (but don't overdo it; they don't like soggy feet).
Some perennials, like hostas, peonies and daylilies, need to be pruned in fall to avoid winter damage. Plants like these should be pruned after the first few frosts in late fall or early winter. Other perennials like mums and coneflowers are better off being pruned in spring just before new growth comes in.
Some Plants Are Especially Cold Hardy
Many cold hardy perennials, shrubs and trees are excellent candidates for fall planting. In general, plants with USDA cold hardiness ratings of 3, 4 and 5, are the best candidates for fall transplanting in cold winter climates.
Other tried-and-true, cool weather annuals for you to replace your tired summer flowers in either beds or containers—pansies, violas, dianthus, sweet alyssum, and snapdragons. For green interest, plant dusty miller and ornamental peppers, cabbage, and kale.
October has two birth flowers: the Marigold and Cosmos. Both stems prosper during the summer and fall and have rich legacies in history, gardening, and folk medicine. The first October birth flower is the cosmo.
The date that your ground actually freezes varies from year to year, of course, and some areas won't have frozen ground at all. If you're unsure, mid-November is a safe planting deadline for nearly everyone. - Get everything in the ground before the ground freezes.
The poinsettia plant! Known for being a classic symbol of the Christmas season, the poinsettia plants' vibrant red bracts and green leaves make it a wonderful addition to any winter home in need of a splash of color.
There are a few bulbs that are winter blooming flowers. Dainty and delicate, snowdrops (Galanthus) are true spring harbingers. No bigger than a dandelion, they bravely push through snow and even ice to grace the garden with their dangling white bell blooms.
Chrysanthemums, also known as mums, are the star of fall gardens. They're usually the last plant to bloom before frost, ushering your garden into the big sleep of winter with a last bang of color.