Stock Video - Autumn planting of onions in the garden. Onions are a popular vegetable for home gardeners to plant in the autumn. Onions can be planted as sets, or seeds can be sown directly into prepared soil. Onions grown from sets will be ready to harvest earlier, usually by midsummer, and provide a steady harvest throughout the season. When planting directly from seed, it may take up to 3-4 months for harvesting to begin. The key to success in growing onions is providing ample moisture by irrigating 1-2 times a week and some light fertilizer when preparing the soil. Being biennial, onions planted in the autumn will overwinter and produce their seed stalk the second year. Onions may be stored in a cool, dry garden area or in a root cellar, allowing them to be enjoyed throughout the season.