This is not something we did in the Midwest, but Angela of Backyard Garden and Gifts (see my blogroll) highly recommends it. After your bulbs have been in the ground for a year, begin digging them and chilling them for 6- 14 weeks each Fall. I suspect that it forces the bulb to dormancy, which our St. George weather can’t be counted on to do. Make certain to remove any fruit from the refrigerator in which you chill them, as the the ethylene gas emitted by ripening fruit (apples and pineapple are the worst offenders) tends to ruin the bulbs.
Now before you dig them, you need to decide which bulbs to plant. There are several proven to in mild winter climates such as ours. Among them are daffodils, certain tulips, crocus, hyacinth, Asiatic lilies, iris and muscari (aka grape hyacinths).
As to the ‘when’ of planting bulbs in the St. George area, December and January are the preferred months, however, if you are a gardener who likes to take risks, you could plant as late as the month of March. Just make certain the spot you have chosen is in well-drained soil. Soggy soil will drown bulbs.
As with bulbs planted in other climates, make certain to fertilize for sturdy roots and optimal flowers, and water during the dry periods.
Bulb on, fellow gardeners. We just need to remember to chill!