Onions are easy to grow—and an essential ingredient in so many recipes. Want onions in a hurry? Start with plants and you'll harvest bulbs just 3 ½ months after planting. Many gardeners also like onion sets for their ease of planting and quick results. When selecting onions, remember that "long day" type onions, which need 13-16 hours of daylight, do best in the Northern zones; "short day" types do best in the Southern zones and thrive in regions with a mild winter climate. "Day-neutral" types are grow well in most zones.