8.9 Disorders: Frost damage
Minor frost damage caused before the plants emerge retards growth and cause the plants to grow twisted. Many leaves turn yellow-green and are rough to the touch. Within the flower stems cavities may develop where the stems break easily. The basal plate is glassy and pale grey.

Severely frost-damaged plants do not emerge.

Cause
Frost damage occurs when the bulbs are stored for some time at temperatures below -1°C. Minor damage occurs after two days at a temperature below -2°C and gradually becomes more serious the longer the bulbs are stored at this temperature. Lower than -5°C serious damage occurs even after a few hours.

Prevention
- Always plant the bulbs upright.
- Prevent heat loss and the occurrence of dry soil on the standing ground and in the mobile greenhouse.
- Place the trays level onto the ground. Make sure there is no gap.
- Cover the narcissi on the standing ground, those on mobile sites and the greenhouse border soil making sure to keep a stack of the greenhouse soil and always keep a stock of plastic or bubble sheeting ready in the border soil for this purpose.