Hyacinths in your garden can grow up to 3-feet tall with curved leaves and a spike of fragrant flowers that can extend up to 12 inches. Hyacinths are spring flowering bulbs, but you can force them to bloom indoors during the winter before you plant them in your garden in the spring. Temperature is the most important factor in successfully forcing hyacinth flowers, but a special bulb jar will also aid the process.
Select a bulb jar for you hyacinth bulb. Also called forcing jars, the crystal or glass container is shaped like an hour glass with a large water reservoir at the base, a pinched waist that separates a bowl at the top where the hyacinth bulb rests. As the hyacinth bulb grows, the roots go into the water reservoir.
Select a large, healthy hyacinth bulb for planting in your bulb jar. The optimum time for planting hyacinths in a bulb jar is in the fall. If your goal is to have Christmas blooms, you should plant hyacinth bulbs in September.
Fill the reservoir with water up to within quarter inch below the waist of your bulb jar. Add activated charcoal to the water to help keep it fresh longer.
Place the hyacinth bulb in the bowl with the bottom of the bulb facing down. Make sure that the water does not touch the bulb or it could rot.
Place the hyacinth in a dark location with temperatures around 40 degrees Fahrenheit for 13 weeks. Select a refrigerator that is rarely opened or a cellar for best results. Hyacinths need a period of cold in order to force the blooms. If you place them in a fridge, do not store fruit in the same location as the gas they produce can harm the developing flower.
Check your hyacinth periodically to top up the water. When the bulb shoots are at least 2 inches tall and the roots reach the bottom of the water, move the plant to a slightly warmer location with low-light conditions. Over the next four days, gradually move your hyacinth to successively warmer spots with increased light. Ultimately, place your hyacinth plant in a sunny windowsill with average temperatures of 60 to 65 F. This will help the foliage develop. When the flower appears, turn the plant daily so the flower will not lean. Hyacinth flowers enjoy bright, indirect light.
Plant your hyacinth in a sunny spot in your garden after the last frost. You cannot force the same bulb to bloom again in water.