Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
9/16/02
Contacts:
Richard Jauron, Extension Horticulture, (515) 294-1871, rjauron@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
Yard and Garden Column for the Week Beginning Sept. 20, 2002
Enjoy Spring-Flowering Bulbs Indoors and in the Garden
By Richard Jauron
Horticulture Specialist
Iowa State University Extension
Tulips, daffodils, crocuses and other spring-flowering bulbs are a welcome sight in spring. Gardeners also can enjoy spring-flowering bulbs during the winter by forcing them indoors.
Forcing Spring-Flowering Bulbs Indoors
Spring-flowering bulbs that can be forced indoors include tulips, daffodils, hyacinths and crocuses. Although many bulb varieties can be forced, best results are obtained by selecting varieties recommended for forcing. To enjoy spring-flowering bulbs in winter, gardeners must begin the forcing process in late summer or early fall. Gardeners need good quality bulbs, a well-drained potting mix and containers with drainage holes in the bottom.
Begin by partially filling the container with potting soil. Set the bulbs so that the tops of the bulbs are even with or slightly below the rim of the container. Place additional potting soil around the bulbs. However, don't cover the bulbs completely. Allow the tops (noses of the bulbs) to stick above the potting soil. After potting, water each container thoroughly.
To bloom, spring-flowering bulbs must be exposed to temperatures of 40 to 45°F for 12 to 16 weeks. Possible storage sites include the refrigerator, root cellar or an outdoor trench. During cold storage, water the bulbs regularly and keep them in total darkness.
Once the cold requirement has been met, begin to remove the potted bulbs from cold storage. For a succession of bloom, remove pots from storage at 10-to 14-day intervals. Place the bulbs in a cool (50 to 60°F) location that receives low to medium light. When the bulbs begin to grow, move the plants to a slightly warmer area that receives bright light. Keep the potting soil evenly moist during the forcing period. Flowering should occur in 3 to 4 weeks.
Tulips and most other spring-flowering bulbs are normally discarded after forcing. Attempts to save most forced bulbs are usually unsuccessful as most do not bloom again when planted outdoors. Forced daffodils, however, can often be successfully planted outdoors.
Planting Spring-Flowering Bulbs Outdoors
October is the ideal time to plant spring-flowering bulbs in Iowa. If
weather permits, bulbs can be planted as late as mid- to late November.
Most bulbs perform best in partial to full sun. Bulbs also need a well-drained,
fertile soil. Poorly drained soils can often be improved by incorporating
organic matter, such as compost or peat.
Plant spring-flowering bulbs in clusters or groups to achieve the greatest visual impact in the garden. When planting daffodils or tulips, plant 10 or more bulbs of the same variety in an area. Smaller growing plants, such as grape hyacinths and crocuses, should be planted in clusters of 50 or more bulbs. Plant bulbs at a depth equal to 2 1/2 to 3 times their maximum bulb diameter. Accordingly, tulips and daffodils should be planted 6 to 8 inches in depth, crocuses and grape hyacinths only 3 to 4 inches in depth. Large bulbs, such as tulips and daffodils, should be spaced 4 to 6 inches apart. A 3-inch spacing is adequate for crocuses, grape hyacinths and other small bulbs.
If fall weather is dry after planting, water the bulbs periodically to promote good root development.
Forcing spring-flowering bulbs indoors is an excellent way to brighten the cold, gray days of winter. Planted outdoors, the bright, cheery flowers of spring-flowering bulbs herald the arrival of spring.
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