Forcing Spring-Flowering Bulbs

Tulips, daffodils, hyacinths, and crocuses are a welcome sight in spring. Gardeners can also these enjoy spring-flowering bulbs during the winter months by forcing them indoors. 

To enjoy spring-flowering bulbs in winter, gardeners must begin the forcing process in late summer/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. Then place the bulbs on the soil surface. Adjust the soil level until the tops of the bulbs are slightly below the rim of the container.  Place additional potting soil around the bulbs.  Allow the tips of tulip, daffodil, and hyacinth bulbs to stick above the potting soil.  Crocus bulbs should be planted about 1 inch deep.  For ease of watering, the level of the soil mix should be ½ to 1 inch below the rim of the container.  Label each container as it is planted.  Include the name of the cultivar and the planting date.  After potting, water each container thoroughly. 

The number of bulbs to plant per pot depends on the type of bulb and size of the container.  A 6-inch-diameter pot will accommodate six or seven tulips, four or five daffodils, three hyacinths, and 12 to 15 crocuses. 

In order to bloom, spring-flowering bulbs must be exposed to temperatures of 40 to 45̊Fahrenheit 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.  For a succession of bloom, remove pots from storage at 10 to 14 day intervals.  Place the bulbs in a cool (50 to 60̊Fahrenheit) 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 forced bulbs are usually unsuccessful as many don’t bloom again when planted outdoors.  Forced daffodils, however, can often be successfully planted outdoors. 

Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on October 11, 2019. The information contained within may not be the most current and accurate depending on when it is accessed.