Forcing Flowering Bulbs for Indoor Beauty

If you want to enjoy beautiful blooms indoors for winter and spring, October is a good time to get started. Spring blooming bulbs such as tulips, daffodils, hyacinths, and crocuses, as well as bulbs typically associated with the winter holiday season, amaryllis and paperwhites, are all great choices. To ensure beautiful indoor blooms at the time you would like them, you will need to employ a process known as forcing. Forcing is a method of growing plants that makes or forces them to flower at a different time than they would under normal conditions. This is achieved by simulating natural growing conditions to initiate flower buds at a desired time. Professional growers routinely use this process to provide stores with Easter lilies, daffodils, and tulips in the early spring and poinsettias in the winter, just in time for the holiday season.

Bulbs can be divided into two groups, those that require chilling and those that do not. All spring bulbs require chilling. Amaryllis and paperwhites do not. Of the spring bulbs, hyacinths and daffodils are usually the easiest to force, with tulips being slightly more difficult. Small bulbs, such as crocuses, grape hyacinths, and snowdrops, may also be forced. To understand why a chilling period Is important, consider how spring bulbs grow naturally outdoors. They grow leaves in the spring, enabling them to store energy in the bulb for the following year. After blooming, their leaves die back, and they go dormant during the summer. They receive a natural chilling period during the winter, and during that time, root growth begins. As the soil warms in the spring, the chilling period ends, and they begin to grow and eventually bloom. In order to have them bloom at a specific time indoors, this process needs to be simulated. Depending on the type of bulb, they require 12 to 18 weeks of chilling time in order to flower. Chilling breaks their dormancy period, allowing the bulbs to develop a root system, leaves, stems, and flower buds. Once the chilling period ends, the bulbs typically take 2 to 6 weeks to grow and bloom. To force the bulbs indoors, decide on a date you would like them to bloom. From there, count back 14 to 19 weeks, which is the sum of the chilling requirement and the time until bloom.

Purchasing quality bulbs is your next step. Spring-blooming bulbs can typically be found in stores from September through November, as this is the time they would be planted outdoors to bloom naturally in the spring. Amaryllis and paperwhite bulbs typically make their appearance in stores in November and December. Select large, firm, unblemished bulbs, as withered or damaged bulbs may bloom poorly. Larger bulbs typically will produce the largest, most attractive flowers.

To force spring bulbs, choose a container with good drainage, preferably plastic or clay. Partially fill the container with potting mix. There should be at least 2 inches between the bottom of the pot and your bulbs, and the tops of the bulbs should be even with the top of the pot. Since good drainage is important, a blend of equal parts sphagnum peat, vermiculite, and perlite works best. Fertilizer is not needed at this point. Place the bulbs on the soil surface. Flat-sided bulbs, such as tulips, should be placed with the flat side next to the edge of the container to allow their leaves to form a border around the edge of the pot. Bulbs may be placed close together in the pot, about half of a bulb width apart, as this will create a more attractive display. Fill the container with more potting mix, leaving just the very tips of the bulbs exposed. Water them thoroughly, and do not allow the containers to sit in residual water. Store them in a cool, dark place for the length of their chilling period. The optimal chilling temperature is between 40 to 45°F, so a refrigerator, cool cellar, or garage may work. If using a refrigerator, do not store near ripening fruit, particularly apples. These give off ethylene gas which may inhibit growth and flower development. Check them periodically to be sure the potting mix is not drying out, and if dry, add a small amount of water. It is important not to overwater. Once the chilling period is complete, remove them from their storage area and bring them into a location that receives medium light. At this point, shoots will have developed. These may be white since they have been stored in the dark, but they will green up once they are brought into the light. Once this happens, they may be placed in a sunny location. As they begin to bloom, remove them from direct sunlight to increase the length of bloom time.

Since amaryllis and paperwhites do not require chilling, they take less time to bloom after potting. As with spring bulbs, select a pot and potting mix that drains well. For amaryllis bulbs, the pot should be one inch wider than the widest part of the bulb and twice as tall. A slightly pot-bound bulb will bloom better. Fill the pot half full with new potting soil. Place the bulb in the soil so that the top of the bulb sits slightly above the edge of the pot. Add more soil around the bulb, allowing one-third to one-half of the bulb to remain visible. Keeping the top portion of the bulb uncovered will help prevent fungal disease. Water thoroughly when planting and when soil feels dry to the touch, about once a week, after that. Place it in a sunny window. They will typically take 6 to 12 weeks to bloom, depending on the variety. Once flower buds begin to open, move the pot out of direct sunlight and away from heat sources to prolong flowering. When planting paperwhites, select pots that are three to five inches deep. Plant enough bulbs to fill the pot, allowing room between them so they do not touch, and cover with enough potting mix so that only the tips are exposed. Place them in a cool, sunny location, and they will flower in 4 to 8 weeks. If the location does not have enough light or is too warm, the plants may become leggy and flop over. As with the other bulbs, move into an area out of direct sunlight once they begin to flower to prolong bloom time.