If basic cultural requirements are met, spring flowering bulbs force well for indoor winter bloom. Tulips, hyacinths, daffodils, crocus, muscari, and many others may all be used for forcing. The Paperwhite Narcissus group, fall blooming crocus, and Colchicums are by far the easiest to handle since the bulbs do not need a cold treatment. Hyacinths, Muscari, and Galanthus are easily forced, but tulips and daffodils are a little more difficult. By choosing from the varieties listed in this cultural guide and following the instructions given, you should have good success.

Indoor forcing of bulbs means they must be given the same natural conditions they receive outdoors. They must have first, proper planting; second, cold temperatures for rooting; third, warmth and sunshine for flowering. A cool growing temperature for developing strong root systems is most important to get your bulbs off to a good start. Without this, plants tend to develop "blind" growth without flowers.

If you are not ready to pot the bulbs when they arrive, they can be stored in mesh or paper bags in the refrigerator or in a cool basement where the temperature ranges from 35° to 50°F. Do not store bulbs with fresh fruit because the fruit releases ethylene gas which can prevent proper flowering.

Planting: Bulbs can be grown in almost any container that has good drainage and is at least twice as deep as the height of the bulb. Bulb pans, which are wider than they are tall, are ideal since they do not tip over easily. GOOD DRAINAGE IS ESSENTIAL. Some containers may need gravel or broken pottery placed in the bottom to insure good drainage. Use a good soilless potting mix or a mixture of 2 parts good garden loam to 1 part sand. For bulbs that will be transplanted in the garden after forcing, add 1 tablespoon of 5-10-5 fertilizer to each 6 inch pot of soil. Place each bulb about 1/2 inch apart, with the pointed end facing up and just even with the soil level. Tulip bulbs should be planted with the flat side facing the edge of the pot so that the first large leaf will cover the rim of the pot. Water thoroughly.

Cold Treatment: These bulbs require low temperatures, moisture, and darkness for rooting and early growth stages. After potting, place the bulbs in a refrigerator, cool base- ment, cold frame, unheated garage, or in a trench outdoors where the temperature will average between 35° and 50°F. For pots placed in a cold frame or unheated garage, mulch with straw, pine needles, or leaves to protect them from freezing temperatures. Check every 3 to 4 weeks to make sure the soil remains moist. In colder areas, dig a trench deep enough to put the pots below the frost line. A 1 inch layer of gravel or sand in the bottom of the trench will provide good drainage. Surround and cover the pots with loose soil, compost, shredded leaves, or more sand until the trench is filled. As the ground begins to freeze for the winter, cover the trench with a 6 inch mulch of straw, pine needles, shredded bark, or shredded leaves. Leave the pots in cold storage for the minimum number of weeks listed on the following chart. They can be left in cold storage longer if necessary.

Move the bulbs indoors to a cool area to gradually acclimate them to warmer growing conditions. Place them in a shaded area with a temperature of 55° to 60°F for about a week. As soon as the shoots turn green, move them into direct sun in a room with a daytime temperature below 65°F. Water as needed to keep the soil moist. For a succession of bloom through the winter, move a few pots indoors at 10 to 14 day intervals. As the flowers fade, remove the stems but allow the leaves to grow. Since bulbs that have been forced need to build up energy to flower again, it is best to transplant them outdoors as soon as the ground is workable. Tulips do not always rebloom reliably, so they are usually discarded after the flowers fade.

Forcing Varieties                                                           Cold Storage Time

Hyacinth - Jan Bos                                                                13 Weeks
Pink Pearl
Carnegie
City of Haarlem
Blue Jacket

Daffodil - February Gold                                                       13-15 Weeks
Geranium
Ice Follies
Jack Snipe
Mount Hood
Tete-A-Tete
Thalia

Crocus - All varieties except Yellow Mammoth              13-15 Weeks

Tulips - Angelique                                                                     15 Weeks
Apricot Beauty
Plaisir
Red Emperor
Red Riding Hood
Yellow Present

Muscari - All Varieties                                                                 15 Weeks

Iris - Dutch                                                                                   4-6 Weeks
reticulata & danfordiae                                                               14 Weeks

Galanthus                                                                               12-15 Weeks
Eranthis                                                                                   12-15 Weeks
Chionodoxa                                                                            12-15 Weeks

Water Culture of Narcissus and Hyacinths

Paperwhite Narcissus varieties and pre-cooled hyacinths that are listed for forcing can be grown in water. Paperwhite Narcissus bulbs should be planted in shallow bowls or pots filled with pebbles and water. For a spectacular show, use as many as will fit into the container, allowing them to touch. Add enough pebbles to cover the bottom 1/4 of the bulbs to hold them in place. Fill the container with water so that it is just below the base of the bulbs. Add water as needed to maintain this level. Place the prepared bulbs in a cool (50°F), dark location for about two weeks. When the shoots are 3 to 4 inches tall, move the pots to a sunny window and rotate daily to keep the stems straight.

Pre-cooled hyacinth bulbs can be forced into bloom in hyacinth glasses. These special glasses hold the bulbs above the water level but allow the roots to grow down and into the water. Add a few bits of activated charcoal (which is used in aquariums) to keep the water fresh. Place the prepared bulbs in a cool (50°F), dark area for 6 to 8 weeks. When the top growth reaches 2 to 3 inches, gradually move the glasses into brighter light each day for several days. Continue to provide a cool temperature and add water as needed. If the flower stem does not elongate properly, place a black paper cone or cylinder over it until it reaches about 6 inches.

 If pre-cooled hyacinths are not available, you can pre-cool regu- lar hyacinth bulbs by refrigerating the  for 4 to 6 weeks in mesh or paper bags. Do not store the bulbs with fresh fruit because the fruit releases ethylene gas which can prevent proper flowering.

Bulbs that are forced in water use so much energy to produce flowers that there is very little left to rebuild them for the next year. They are usually discarded after the flowers fade.