Flowering bulbs come in thousands of varieties, and optimal planting times are dictated by their specific needs to properly break dormancy and set bloom. In the Utah climate, you must decide whether bulbs are appropriate for fall or spring planting. Cold hardy bulbs, which survive or even require extended cold periods to set the bloom cycle, must be planted in the fall. Spring bulbs can be planted when the ground thaws and frosts are less prevalent. Used in formal patterns or en masse natural drifts, flower bulbs create a stunning display in the garden.
Cold hardy bulbs such as tulips and crocuses should be planted in the fall before the ground begins to freeze. Most bulbs thrive when planted 6 inches or more deep. Consult your specific bulb's packaging as desirable planting depth can vary widely. Water your bulb well at planting and do not water again until spring. Apply several inches of organic mulch such as shredded leaves or bark over the planting sites. Also, mark planting locations with a stick or tag to ensure that none of your fall handiwork gets mistakenly dug up.
Bulbs appropriate for planting in spring such as Lily of the Valley and Hyacinth are those that cannot tolerate the cold of overwintering in the Utah ground. These bulbs should be planted after the ground thaws. Most spring bulbs will survive a few frosts in the spring but others must be planted after the last frost has passed. Spring bulbs don't require mulching other than to prevent weeds or for decorative purposes.
Container Planting & Overwintering
Bulbs can also be grown in containers indoors with refrigeration or an unheated outbuilding, which simulates the natural fall and winter chill cycle that sets the bloom. These forced bulbs can be left in their pots and put outside in early spring or carefully planted in the ground or other decorative containers.