CULTURE OF NARCISSUS TAZETTA 'ZIVA' IN THE NETHERLANDS
For bulb production in The Netherlands, bulbs of 'Ziva' are planted outside in spring (about 1 May) and lifted in autumn after the first half of October. After this, the bulbs are stored at 25°C and are given a hot-water treatment in December. The start of bulb production in a given season in The Netherlands can be made with Israel-grown bulbs that have been retarded at 30°C, or with previously forced Israel bulbs which have been treated during at least ten weeks at 30 – 34°C, possibly followed by four weeks at 17°C and which are planted in spring, or with Israel-grown bulbs that have been chipped in winter and then stored for twelve weeks at 25°C before planting.
The optimum storage temperature for promoting flower induction lies between 23 and 27°C, and should be applied for 4–5 months. Flower induction, rate of growth and crop quality are influenced by storage temperature and period, and by treatment with ethylene or carbon monoxide.
For cut-flower production, storage at 25°C followed by four weeks 17°C gives quite satisfactory results.