How to force bulbs in the winter
I can't think of a better way to perk up the cloistered days of winter than by creating a little spring inside my house by forcing bulbs. For the most part, it's really easy to accomplish.
The term "forcing" refers to the fact that you're tricking the bulb into believing it has already passed through its winter dormancy to prepare for flowering.
Each species of bulbs has specific requirements involving how long they like to hibernate and at what temperature they like their sleeping quarters. For instance, hyacinths (Hyacinthus orientalis) like to be knocked out for 12 to 15 weeks; tulips (Tulipa sp.), 15 to 16 weeks; and hardy daffodils (Narcissus pseudonarcissus), 15 to 16 weeks. But a general range for hardy bulbs -- tulips, daffodils, crocuses (Crocus sp.), and hyacinths -- is 13 to 15 weeks at 35 to 48 degrees Fahrenheit.
Potting bulbs to grow in the winter
For potting, follow the rule of planting two to three times as deep as the bulb is high. Amaryllises (Hippeastrum x hybridum) are the exceptions: Leave one-third of the bulb showing. Remember to fertilize (follow the directions on the label).
Bulbs that require cold treatment should be potted and stored in a cold frame, an unheated garage, or the vegetable drawer of your refrigerator for 13 to 15 weeks. (If you use the refrigerator, don't place the plant near apples -- the ethylene gas they emit can "blast" the flowers.) Once shoots are an inch high, take the pots to a bright, cool spot (about 55 F to 60 F) for flowering.
Easy bulbs to force in the winter
Amaryllises and Paperwhites(Narcissus) are available on amazon, or from the fall through the spring at your local drug store, supermarket, or florist. To bloom, they just need to be planted. No fuss, no muss.
Amaryllises are native to South Africa. When you buy them, they already have had their dormancy. It can't get any easier. However, to keep them blooming for years, you'll have to follow these directions.
Assuming you bought them near the holiday season, you'll need to keep them fertilized, well lit, and watered until next October. If you can provide a summer spot outdoors, all the better. Then, most horticulture resources say to take them inside and slowly reduce watering until the leaves turn brown. At that point, cut off the leaves, place the pot in a cool, dark spot (such as a closet) for eight weeks, repot the plant, and resume watering. If the bulb has gotten enough light and vitamins during the year, it should flower again, and may have even multiplied.
Paperwhites are non-hardy varieties -- they can't be saved to bloom for the following year. But in addition to growing in potting soil, they also thrive when grown hydroponically -- in water, with gravel as a base. Some are delightfully fragrant.
Slightly More Challenging
Prechilled hardy bulbs (tulips, crocuses, hyacinths, etc.) are available on amazon. These have been forced into, or have had, some or all of their dormancy. To make sure, give them the cold treatment as described earlier until they're ready for flowering.
Hardy bulbs that haven't been prechilled are available on amazon or from your local nursery in the fall. Give them the cold treatment for 13 to 15 weeks.
Freesias (Freesia sp.) are available on amazon. They offer a lovely fragrance and a multitude of colors, but require 60 F days and 50 F nights -- conditions hard to regulate outside a greenhouse.