Forcing Bulbs - Prechilling Chart

Many spring flowering bulbs can be forced into bloom during the winter. Tropical bulbs, like paper whites, don’t require much more effort than potting them in soil or water. However, non-tropical bulbs, that are traditionally planted in the fall, need a period of cold temperatures to stimulate growth and flower production. This cold or chilling period should take place at a temperature of around 35 - 45 degrees F.

Almost any bulb can be forced, but below are some good choices for winter forcing and the chilling periods required. Forcing Flowering Bulbs for Winter Color has more detailed information about forcing bulbs.

Choice Cultivars for Winter Forcing of Spring Bulbs

BULB	Weeks of Prechilling
Amaryllis	None
Crocus, Jeanne d'Arc	14-15
Crocus, Pickwick	14-15
Crocus, Remembrance	14-15
Hyacinth, Carnegie	10-12
Hyacinth, Delft Blue	10-12
Hyacinth, Pink Pearl	10-12
Iris reticulata	1-13
Muscari armeniacum	14-15
Narcissus, Dutch Maste	15-18
Narcissus, Golden Harvest	14-16
Narcissus, Little Gem	14-16
Narcissus tazetta, Paperwhites	None
Narcissus, Tête À Tête	12-14
Scilla tubergeniana	12-14
Tulip, Blenda	14-15
Tulip, Flair	13-14
Tulip, Merry Christmas	14-16
Tulip, Yellow Present	15-16
Tulip, Princess Irene	15-17