University of Illinois Extension
Bulbs & More

Selection

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.

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.

Blooming Season

Spring flowering bulbs normally start blooming in February with snowdrops and end in June with the alliums. The great variety of bloom color, flowering time, plant height and shape makes bulbs a good addition to any landscape or garden.

Obtaining Bulbs

It is important to select good quality bulbs for planting. Factors to consider are size and firmness. Larger bulbs produce larger blooms. Select bulbs that are firm and free from soft or rotting spots or other signs of disease.

It is important to select good quality bulbs for planting.

There are basically three sources for obtaining bulbs: mail order businesses, local nurseries and discount businesses. Normally, there is a larger selection of bulb varieties through mail order catalogs. The disadvantage of mail order is that the buyer does not know what the bulb will look like until received. Therefore always buy from companies that have good reputations and that you or your friends have used in the past with good results.

Once bulbs are obtained either locally or from a mail order source, they should be planted as soon as possible. If the bulbs cannot be planted immediately, keep the bulbs cool until they are planted. The preplanting storage temperature should be between 50°F and 60°F. Keep the bulbs away from ripening fruits that may produce ethylene and cause flowering disorders, especially with tulips.

Sequence of Flowering

Early Spring (weeks 1-4)

  • Snowdrop (Galanthus nivalis)
  • Winter Aconite (Eranthis hyemalis)
  • Danford Iris (Iris danfordiae)
  • Crocus (Crocus spp.)
  • Glory-of-the-Snow (Chionodoxa luciliae)
  • Siberian Squill (Scilla siberica)
  • Striped Squill (Puschkinia scilloides)
  • Grecian Windflower (Anemone blanda)
  • Common Grape Hyacinth (Muscari botryoides)
  • Early Daffodils (Narcissus spp.)
  • Netted Iris (Iris reticulata)

Midspring (weeks 4-8)

  • Checkered Lily (Fritillaria meleagris)
  • Species Tulips (Tulipa spp.)
  • Early Tulips (Tulipa spp.)
  • Early Alliums (Allium spp.)
  • Hyacinths (Hyacinthus orientalis)
  • Summer Snowflake (Leucojum aestivum)
  • Medium-Cupped Daffodils (Narcissus spp.)

Late Spring (weeks 8-12)

  • Dutch Hybrid Iris (Iris hybrids)
  • Midseason Tulips (Tulipa spp.)
  • Late Daffodils (Narcissus spp.)
  • Late Tulips (Tulipa spp.)
  • Alliums (Allium spp.)