Flowering bulbs are an important addition to any landscape or garden. The great variety of bloom color, flowering time, plant height and shape makes bulbs a good addition to the landscape.
Bulbs can be classified as spring flowering bulbs or summer flowering bulbs. Another way to classify bulbs for use in Illinois would be hardy spring flowering bulbs and tender summer flowering bulbs.
Summer flowering bulbs (tender bulbs) are killed by cold temperatures. They must be planted in the spring when there is no longer a chance of ground frost. They need to be dug in the fall following the first frost that discolors the foliage and stored over the winter.
The spring flowering bulbs (hardy bulbs) such as tulips, daffodils and crocus need a cold period during the winter to flower. These bulbs are planted and develop a root system in the fall and bloom during the spring. Temperatures are cold enough in Illinois during the winter to meet these cooling requirements. For instance, tulips require 12 or more weeks of cold temperatures. If spring bulbs are used for forcing indoors, be sure they have been pre-cooled or they will not bloom.