An interesting note about "day-length" and bulbing onions. Onions can be grouped into at least two different categories: short day and long day. These terms refer to the number of daylight hours the variety needs to produce bulbs. Short day onions require about 11-12 hours to halt top growth and start the bulbing process, while long day onions need 14-16. Long day onions are the ones that will bulb up here in the northern latitudes (above 35 deg. N) for your winter keepers.