Spring-flowering bulbs like hyacinth, daffodils, and tulips, are a joyous sight-they are the first heralds of spring in the garden, their hardy flowers poking up through cold ground to signal that the new season is upon us. So perhaps it's no surprise that people also like to grow them inside. Most spring bulbs grown inside are used only once: you buy a flowering bulb, enjoy it, and discard the plant after the bloom is done (or move it outside). However, it is possible to force the bulb into another bloom in successive seasons. Don't be surprised if the plant isn't as vigorous-during forcing, the bulbs are typically deprived of nutrients, so will not be as vigorous the second season. Nevertheless, if you're determined and patient, here are the steps to force a spring-flowering bulb into bloom year after year.
- Store unplanted bulbs in a perforated plastic bag in your refrigerator. Don't place them near apples or fruits that give off ethylene gas, which was cause rot. Bulbs typically need several months of chilling time, so pay attention to the grower's directions and the date you started to chill them.
- To plant the bulbs, place them in slightly damp pots on your porch or in your unheated garage in the fall. Fill the pots with mulch or very coarse potting material. If you live in a place that doesn't drop below 50ºF during the winter, store the bulbs in the refrigerator, with their pots inside plastic bags. When the weather starts to warm, plant the bulbs into the pots you'll display them in. Plant the bulbs with their pointed side up, just under the surface of the soil. Use well-drained, slightly damp potting soil.
- After the chilling period is over (counting any time in the refrigerator), check for roots on the bulbs by looking through the drainage holes. The bulbs might also have a green shoot emerging from the soil. At this point, move the bulbs inside, but keep them in the coolest area possible, with moderate light. They will need another two or three weeks in this environment. During this period, leaves will emerge slowly.
- Increase the light level after three weeks and keep them evenly moist, but don't let it get too warm. They should still be growing slowly, and the warmer it gets, the faster the plant will grow and the shorter the bloom.
After the bloom is over, either discard the bulb or wait until fall and begin the process again. Beware, though, that forced bulbs will continue to lose vibrancy year after year and most indoor growers simply replace their spring-flowering bulbs every year.