Planting flower seeds in the fall and winter provides early cheerful blooms after the dreary winter months--and many flowering plants will not thrive or bloom unless their seeds are sown in the autumn and winter. There are factors, though, that must be considered before sowing fall or winter seeds for successful blooming when spring and summer arrive.
Many bulbs, corms, and seeds need to experience a chilling period in order for blossoms to develop for the following season. Some flowering plant types will take a full year of establishment before flowers can appear.
Successful spring and summer flowering requires understanding the USDA hardiness zone in which the seeds grow. The hardiness zone determines the optimal time for sowing seeds, corms and bulbs for spring and summer flowering. USDA zones 7 through 11 are ideal for planting seeds in the winter months, while gardeners living in zones lower than zone 7 must sow their seeds 2 to 3 months prior to the first autumn frost to allow the seeds to germinate and the root systems to become established.
The main purpose of planting flower seeds in the fall or winter is to obtain successful germination of the seed, bulb, or corn so it flowers the following year. Because perennials and many spring blooming bulbs and corms must have a period of cold, usually 6 to 8 weeks minimum, to activate growth, planting in the fall or early winter easily provides this requirement. Hardy annuals, biennials, and wildflowers are naturally self-sowing, and planting new seeds in the fall simulates the natural growing cycle.
Flowering garden plants that are ideal for fall or winter seed sowing include wildflowers, hardy annuals, biennials, perennials, bulbs and corms. Existing wildflowers and hardy annuals, like California poppies, love in the mist, snapdragons, or bluebells, reseed themselves after the flowers fade and seed heads develop. Gardeners can gather seed heads to reseed in a new location or leave them to reseed on their own. Perennials and biennials grown from seeds need the cold period of winter, but should be planted early enough so the seeds can germinate and the plants can be well established before the first hard frost in the fall.
Fall planting yields a higher percentage of seed germination than winter planting. For gardeners who plant in USDA zones 7 through 11, the seeds and bulbs that require a period of cold must first spend 6 to 8 weeks in a cool environment; a garage refrigerator is ideal for this. Bulbs, corms and seeds should not rest stored near any fruit, particularly apples, because many fruits give off ethylene gas, which can rot them.