Flower initiation in Narcissus paperwhite cv. 'Ziva' in Israel, occurs from mid-July to August. This is a period of high temperatures (30–32°C max.).

Stem elongation inside the bulb, is stimulated by decreasing temperatures in autumn. Bulbs are usually planted in October and flower about 40 days later, at the end of November. It is possible to postpone planting till December without impeding normal flower quality.

Bulbs stored in bulb-sheds with no temperature control cannot be planted later than December without deterioration in flower quality, however, forcing time is shorter from February planting on.

Storing the bulbs at high temperatures (25–30°C) prevents stem elongation and thus allows later planting. Storing bulbs at 25°C made planting till February possible and still ensured flowers of good quality. Forcing time was slightly longer.

Storing bulbs at 30°C enabled planting even in March with good results: longer stems, larger flowers and better quality compared with the two former treatments.

The number of florets however was slightly smaller and forcing duration was 30–40 days longer than in the former treatments, at all planting dates.

Transferring bulbs from 30°C to 25°C prior to planting shortened forcing time without reducing quality and thus enabled cutting flowers of good quality till the end of May.