Several of the fall-planted spring-flowering bulb varieties that mark the end of winter in colder climates can play a role in warm-weather spring gardens too. Most daffodils, some tulips and several other spring-blooming flower bulbs can be grown in areas as warm as Southern California and the Gulf Coast.
A warm climate has the following characteristics:
★ Temperatures can drop to around -5ºC (23ºF) during the winter. (This is typical for climate zones 8-9)
★ Summers are warm and dry.
★ Daffodils (aka Narcissi) are the biggest surprise: most originate in warm Mediterranean regions and will grow readily in USDA zones 9 and 10, requiring no over-winter chilling at all.
★ Classic spring bulbs such as Crocus, Hyacinths and most Tulips are less conducive to warm-climate growing conditions, but can be grown as annuals in warm zones if pre-chilled for 6 to 8 weeks prior to planting. This gives them the solid dose of winter temperatures they require to trigger their spring bloom cycle. Purchase bulbs in the fall for the best selection, and then chill them until planting at 35° F to 45° F (1.5° C to 7° C) in a paper bag kept in a refrigerator crisper drawer. Make sure to keep the bulbs away from any ripening fruits, which give off ethylene gas that can harm the embryonic flower in the bulb.
★ Remove bulbs from chilling in late December to early January and plant immediately. Best performing tulips for warm zones include the Darwin hybrids and many of the long-stemmed Single Late varieties.