Jasper County

Forcing Bulbs for Colorful Bloom Indoors
By: Virgil L. Jones, Master Gardener

If you were unable to get all your crocus, hyacinth, grape hyacinth, daffodil, iris reticulata or tulip bulbs planted outdoors, you can still enjoy their beauty later this winter or early next spring in your home. These bulbs can be made to bloom earlier in the season by means of a process called forcing.

Some varieties of bulbs can be forced easier than others, and usually the ones better suited for this purpose are identified on packages. So, if you are purchasing bulbs for this purpose, be sure to get the ones recommended. The better bulbs for forcing are the ones that have short, thick, sturdy stems, such as Triumph strain of tulips. Those that have long, weak stems will look out of proportion to their container.

The process of forcing is simple, it is just a matter of planting bulbs and allowing them to receive their cold treatment early and allowed to bloom out of season. The bulbs should be planted anytime from early October through November, given a cold treatment and then brought into a warmer area to be forced into bloom.

Plant bulbs for forcing in a clean container with good drainage, in loose potting soil, pea gravel or gravel chips. Place them in containers so they do not touch as they swell somewhat during growth.

For larger bulbs of tulips and hyacinths, a 4-inch pot can hold one bulb, a 6--inch pot can hold three, and a 7-inch pot, five or six. Smaller bulbs, such as crocus and grape hyacinth can be planted with more bulbs to the pot. Place bulbs so their necks stick out about one-half inch above the surface. If forcing tulips, plant their bulbs with the flat side to the outer edge of the pot because the first and largest leaf will grow from this side and will gracefully cover the edge of the pot.

Water the bulbs thoroughly immediately after planting by placing the pot in a shallow pan of water and allowing the pot to soak until the surface of the soil is moist. The pot should not require too frequent watering, but must never be allowed to become completely dry. Bulbs will not need to be fertilized because their food supply has been stored in the bulb.

After bulbs are planted they will require cold treatment. Temperature for this cold treatment should be maintained between 35 and 48 degrees for about 13 weeks. This allows strong root systems to develop, which is necessary for good flowering. Bulbs planted around Thanksgiving will be ready to bring in to a sunny room with temperature around 60 degrees about the middle of February. Warmer temperatures are undesirable as it encourages rapid growth of long, lanky stems and foliage, and smaller bloom. Good storage areas may be difficult to find, but some possibilities are unheated cellars, garages, porches, cold frames, or buried in the garden and covered with a thick layer of straw or leaves to keep the ground unfrozen.

During flowering it is advisable to keep the plants in as cool an area as possible, and keep the plants moist, to encourage longer blooming.

After flowering it is probably best to dispose of bulbs, as most will not flower again, although hyacinths and daffodils, if planted outdoors, may do so. If saving bulbs for reflowering outdoors, then fertilize the plants with a high-phosphorus houseplant fertilizer and keep moist to encourage healthy green leaves for as long as possible. After their foliage has died they can then be planted in the spring to bloom the following year.

For a succession of bloom, bring the rooted bulbs into a warm, sunny area of the home at two week intervals, and enjoy the beauty and fragrance of these colorful bulbs while it is still winter outside.

		University of Missouri Extension Jasper County jasperco@missouri.edu Web site maintained by: Virginia Bryan bryanv@missouri.edu Last updated: 09/02/2009