There are a few different ways to force hyacinth bulbs – the water method and the soil method being the most common.

The water method goes like this:  put the bulbs in a brown paper bag and store in a dark, cool location, at a temperature of about 10 C.  For many of us, that location will have to be the fridge – some lucky souls will have a cold cellar that will do nicely.  Wait 12 weeks.  (This is a long process, so if you’re forcing hyacinths for March or April flowering, start working on this project in mid-November.  Adjust accordingly depending on when you want blooms).    The bulbs need such a long period of cold to form proper, tall flowers – resist the temptation to take them out early.  After 12 weeks you can put them in forcing vases and fill the glasses with water just to the bottom of the bulbs.  Monitor your water levels and do not let them get low at any time.  Keep the bulbs in a cool and dark location outside of the fridge or cellar for about 3 weeks (or once the roots get about three or four centimetres long) and then put them in direct light.  They should bloom within about two weeks.

Except for the growing medium, the “soil” method isn’t much different.  Fill pots with regular potting soil (you don’t need soilless mix or anything special) and loosely set the bulbs on top of the dirt.  Put as many bulbs in the pot as you can, but don’t allow them to quite touch each other.  Sprinkle a bit of soil on top, but leave the tips of the bulbs fully exposed.  Put potted bulbs in fridge or cold cellar, keep moist but not too wet (bear in mind that the fridge is already a moist environment and adjust your watering schedule accordingly), and wait for at least 12 weeks.  Shoots and roots should emerge at around 6 weeks, but be patient.  After 12 weeks, take pots out and put into a sunny window (not too hot, though – nothing with a southern exposure.  North-facing is best).  Keep watered.  Plants should bloom within three weeks.  Once flowers emerge, take the pots out of bright sunlight, as the blooms last longer away from direct light.

Two other points to make:  don’t bother with fertilizer, as the bulbs store their own food.  And beware of the oxalic acid in hyacinth bulbs:  handling them can cause skin irritation so you can either wear gloves while planting or thoroughly rinse the bulbs before planting, which will reduce the annoying rash.

***

ces.ncsu.edu/depts/hort/hil/hil-8507.html

gardenguides.com/300-force-hyacinths.html