Forcing tulip bulbs is a simple process that provides early indoor blooms. The method includes providing enough nutrients and water while mimicking natural cycles. The seasons of fall, winter and spring are condensed into a period less than six months. By choosing varieties carefully and planting in two-week intervals, indoor tulip flowers will bloom continuously during the winter months, from December into March.
Purchase large, healthy tulip bulbs in early fall. Choose firm bulbs from Triumph or Darwin hybrids. Early blooming tulips forced by the beginning of October will bloom by Christmas. Choose from Merry Christmas, Brilliant Star or Christmas Dream for red holiday tulips.
Prepare a potting mix. Use equal parts perlite, peat moss and potting soil. For every two parts of this potting mix add one part coarse sand. Utilize a fertilizer suitable for flowering bulbs, following the manufacturer's directions.
Place the potting mix in a wide, shallow planter or bulb pan, filling it half full. Be sure to choose a planter with drainage holes; tulip bulbs require well-drained conditions. Space the bulbs close together, an inch or two apart. Plant in a circle with the flattest side facing the edge of the container. Add the potting mix until just the tip of the tulip bulbs are showing. Water until the soil is thoroughly moistened.
Tulip bulbs require 14 to 20 weeks of cold temperatures, including a fall-like period of dark, cool temperatures. Keep temperatures above 33 degrees F but below 48 degrees. Water regularly during the cold cycle and cover the bulbs to maintain darkness. The refrigerator or a root cellar works well for forcing tulip bulbs.
Remove the bulbs from cold storage when minimum requirements are met and yellow shoots emerge. Place the container in a cool location of about 55 degrees with moderate light. When the shoots turn green, usually within a week, move the tulip bulbs to a sunny location with temperatures between 60 and 70 degrees.
Water the tulips regularly. Rotate the planter to give equal sunlight to all sides. The tulip flowers bloom about a month after removal from the cold.
Fertilize after the flowers die and continue to water regularly. Plant the tulip bulbs outside once the ground has thawed. Alternately, keep them potted and start the cold-forcing process again in the early fall.