Forcing Spring-Flowering Bulbs

Spring-flowering bulbs, such as tulips, daffodils, and crocuses, herald the arrival of spring in the Midwest. Many spring-flowering bulbs can also be forced indoors during the winter months. If properly planned, brightly colored flowers may be enjoyed indoors from January until spring.

The forcing of spring-flowering bulbs actually begins in the fall. Gardeners need good quality bulbs, a well-drained potting mix, containers, and cold-storage facilities.

Bulbs

Spring-flowering bulbs which can be forced include tulips, daffodils, hyacinths, and crocuses. While most bulb varieties can be forced, best results are obtained by selecting varieties which are recommended for forcing. Select large, firm bulbs. Small bulbs may bloom poorly, if at all.

Potting Mix

Commercial potting mixes can be purchased at garden centers and nurseries. Choose a high quality potting mix that drains well. Gardeners can also prepare their own medium by mixing equal parts garden soil, peat, and perlite. Pasteurize homemade soil mixes before use.

Containers

Bulbs can be forced in plastic, clay, or ceramic containers. Almost any container can be used as long as it has drainage holes in the bottom. If the containers have been used previously, wash them in soapy water and then rinse in a 1 to 9 solution of chlorine bleach and water.

Forcing Procedure

  1. Partially fill the container (pot) with potting mix
  2. Place the bulbs in the pot so that the tip of each bulb is even or slightly below the rim of the container. The bulbs should be planted closely together. For example, six tulip bulbs or 12 to 15 crocuses can be planted in a 6-inch diameter pot.
  3. Add additional potting mix and firm it around the bulbs. However, don't cover the entire bulb. Allow the nose (top) of the bulb to stick above the soil surface. The soil level should be 1/2 to 1 inch below the rim of the container.
  4. Label each container as it is planted. Include the name of the variety and planting date.
  5. Water each container thoroughly.
  6. Place the bulbs in cold storage for a period of 12 to 16 weeks at a temperature of 40 to 45 degrees F. A refrigerator, cold frame, or root cellar are possible storage sites. Burying the potted bulbs outdoors in a trench is another alterna tive. The bulbs should be kept in complete darkness during the cold treatment. Periodically water the bulbs during cold storage.
  7. Once the cold requirement has been met, the containers can be removed from cold storage. Place the bulbs in a cool (55 to 60 degrees F), semi-dark location. Keep the potting soil evenly moist throughout the forcing period. Move the pots to a slightly warmer area which receives direct sunlight when the shoots turn green. As the plants grow, turn the pots periodically to prevent the plants from leaning.
  8. Flowering should occur in 3 to 4 weeks.
  9. For a succession of bloom, remove pots from cold storage at 10 to 14 day intervals.

This article originally appeared in the October 8, 1999 issue, p. 127.

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