Woodstock Hyacinth Bulb Forcing Kit - Clear Glass Vase with Woodstock Hyacinth Bulb
To force hyacinths on water, set a bulb just above — but not touching — the water in a forcing vase or other container. Put it in a dark, cold area to root for 8-16 weeks. This could be an unheated mudroom, attic, or garage; a cold-frame; or possibly your refrigerator, though many refrigerators are too cold for optimal forcing. The temperature during this rooting period is critical: 40° to 48° F is ideal. Avoid freezing temperatures. The best way to monitor the temperature is to use a maximum-minimum thermometer available from any good garden center.
If the water gets murky, change it. When roots fill the glass and there’s an inch or two of top-growth, bring it into subdued light and warmer but still cool temperatures (about 60° F; again, a max-min thermometer will make this easy). After 7-10 days, move it into bright light, but keep it as cool as you can and avoid direct sunlight. Turn it every day to keep it growing upright.
If your hyacinth spikes start to bloom while much too short, that usually means they didn’t get enough rooting time at 48° and below — which is essential for them to develop the gibberellic acid which allows bloom stalks to lengthen. (This is Mother Nature’s clever mechanism for keeping hyacinths and other bulbs from sending up their bloom stalks during mid-winter thaws.)