By sowing hardy annual flower seeds in autumn, the flowers develop a bigger root system than plants sown in spring. A bigger root system means lots more flowers. You can either sow these flower seeds direct into the ground, or sow in modules for planting out in late Autumn if the weather is mild, or overwinter in a coldframe or cold greenhouse for planting in spring. Some hardy annuals do better if sown in modules and overwintered undercover or with the protection of fleece.
Direct Sowings of flowers: Prepare your soil to a fine tilth, then draw drills about a foot apart in the soil and sow the flower seeds into these lines. This shows you which are your flower seedlings and which are weeds. Flower seeds should be sown fairly thinly and when seedlings are large enough to handle, thin to about 3 inches apart. you can thin again a few weeks later if they are crowded, but leave the final thining till March.
Module Sowings of flowers: Sow the flower seeds very thinly in modules, then thin to one seedling per module segment when large enough to handle. Large flower seeds can be sown one per module segment. Keep moist but never over water, especially in cold weather. Keep modules in a coldframe or greenhouse, or cover with several layers of fleece. Plant out in garden borders in March to or when soil is workable, to the recommended planting distances show on the seed packets.
Good hardy annuals that need little or no winter protection are: Ammi majus, Calendula, Cornflower, Larkspur, Poached Egg Plant, Flax, Nigella, Corn and Opium Poppies, Scabious.
Hardy annuals that would benefit from a little winter protection are: Sweet Pea, California Poppy, Gypsophila, Mallow, Cerinthe, Clary, Linaria.