Q. How do I grow spring-flowering bulbs in warm climates?
A. It's possible to grow spring-flowering bulbs in climates as warm as Zone 9 and Zone 10. However the blooming season in these zones is much earlier than in cooler zones. Some spring-flowering bulbs recommended for Zone 9 can be planted with no pre-cooling. Others will need a special cold treatment before planting.
No pre-chilling needed: Amaryllis, Allium neapolitanum, Allium rosenbachianum, Anemone de Caen and Anemone St. Brigid, Brodiaea laxa, Crocus chrysanthus (snow crocus), Dutch iris, Freesia, Ixias, Lilies, all Narcissi/Daffodils, Ornithogalum umbellatum, Ranunculus, Scilla campanulata (wood hyacinth), Sparaxis, Triteleia uniflora and Tritoni.
Pre-chilling needed: tulips, hyacinths, crocus and the other spring-flowering bulb favorites.
Here are some warm winter gardening tips:
First, choose cultivars which have proved to do well in warmer climates. Cold-hardy bulbs that need pre-cooling in warm winter regions must be treated as annuals and new bulbs must be planted the following fall. Pre-chill the bulbs for a minimum of six to eight weeks in a refrigerator at a temperature of around 40°F to 45°F (the temperature of most home refrigerators). If you use a refrigerator, be sure not to store any apples or other fruits alongside your bulbs. Ripening fruit naturally gives off ethylene gas which will kill the flower inside the bulbs.
Don't worry if you bought the bulbs early in the season and need to store them for several months before planting. Keep them chilling — even up to 16 weeks if necessary, until it is time to plant. Optimally, the bulbs should be put in the ground in December or early January. Plant tulips about 6 to 8 inches deep, water well and protect with a layer of mulch to retain moisture and protect from heat. When bulbs do not receive sufficient weeks of cold treatment, they bloom too close to the ground, on too-short stems.