4.9 Rooting room: Temperature
For early forcing (until December) of bulbs planted in trays, maintain a temperature of 9°C throughout the cold period. From December, however, this temperature will drastically increase shoot development. In order to avoid the plants from growing crookedly, use trays that are deep enough or leave sufficient room between the stacked trays.

For later forcing (flowering from January), maintain a minimum temperature of 7°C. Only when there is a risk that the shoots could become too long the temperature should be dropped to 5°C. An extended period (4 weeks or more) at this low temperature will result in a shorter crop and a longer period in the greenhouse compared with bulbs stored outside on a standing ground.