By Richard Jauron, Laura Sternweis
Spring-flowering bulbs, such as tulips and daffodils, must be planted in the fall so their blooms may be enjoyed in the spring. Iowa State University Extension and Outreach horticulturists offer tips on planting, storing and forcing spring-flowering bulbs. For answers to additional questions, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.
When is the best time to plant tulips, daffodils and other spring-flowering bulbs?
October is the ideal time to plant tulips, daffodils and other spring-flowering bulbs in Iowa. When planted in October, spring-flowering bulbs have sufficient time to develop a good root system before the ground freezes in winter. If weather permits, bulbs can be planted as late as late November/early December.
What is a good storage site for spring-flowering bulbs?
Tulip, daffodil, hyacinth and other spring-flowering bulbs usually begin arriving in garden centers and other retail businesses in late August. Spring-flowering bulbs purchased in late summer should be stored in a cool, dry place (such as a garage or basement) until they can be planted in fall.
How do I force spring-flowering bulbs indoors?
Spring-flowering bulbs that can be forced indoors include tulips, daffodils, hyacinths and crocuses. 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 (pot) with potting soil. Then place the bulbs on the soil surface. Adjust the soil level until the tops of the bulbs are even with or slightly below the rim of the container. Generally, three hyacinths, three to five daffodils, five to seven tulips or 10 to 12 crocuses can be planted in a 6-inch-diameter pot. After arranging the bulbs in the pot, 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.
In order to bloom, spring-flowering bulbs must be exposed to temperatures of 40 to 45 degrees Fahrenheit for 12 to 16 weeks. Possible storage sites include a refrigerator, root cellar or an outdoor trench. (When using the refrigerator for cold storage, place the potted bulbs in a plastic bag if the refrigerator contains apples or other ripening fruit. Ripening fruit give off ethylene gas that may impair flower development.) During cold storage, water the bulbs regularly and keep them in complete darkness.
Once the cold requirement has been met, begin to remove the potted bulbs from cold storage. Place the bulbs in a cool (50 to 60 F) location that receives low to medium light. After four or five days, move the plants to a warmer (60 to 70 F) area that receives bright light. Keep the potting soil evenly moist during the forcing period. Flowering should occur in three to four weeks. For a succession of blooms, remove pots from storage at 10- to 14-day intervals.