Narcissus and Daffodil

Production of Narcissus bulbs 65
although the growing season is delayed, growth then takes place under higher
light levels and longer days. Rees (1972) compared the growth of identical stocks
of narcissus ‘Fortune’ grown in south-west and eastern England. In the southwest,
emergence, anthesis and senescence occurred 2–4 weeks earlier than in the
east. After planting, the rate of dry weight loss was faster in the south-west and
minimum plant weight was reached sooner, presumably because of the higher soil
temperatures. Although bulb weight also increased sooner in the south-west, the
eventual bulb yields were higher in the east. Annual temperatures and rainfall for
important bulb-growing areas are given in Figure 4.1.
There are large differences between years in narcissus yield, quality and timing,
much of which may be attributable to weather conditions (Hanks, 1996a).
Szlachetka and Romanowska (1990) carried out long-term trials, and reported
that weather conditions, especially in December, had an effect on bulb yield
greater than the effect of the grade of planting material used. Where the mean
monthly air temperature was above 0 °C or slightly below (–0.8 °C) and the soil was
not frozen, bulb yield was high; if the temperature was below –3.6 °C and the soil
was frozen, yield was decreased by 14–48%.
Narcissus bulbs are generally regarded as suitable for naturalising in US
climatic zones 4 (annual minimum temperature about –30 °C) to 8 (about –10 °C)
(De Hertogh, 1989; De Hertogh et al., 1993). Information on the hardiness and
performance of a range of cultivars is available from trials such as those described
by Klingaman and Eaton (1983) and Nelson (1988). In the Netherlands and
similar climates, narcissus crops are covered (e.g., with straw) to protect them from
frost or other injury. In the UK, crop covers are not used, as soils seldom freeze to
sufficient depths to damage bulbs of most cultivars. Tazetta narcissus cultivars are
hardy in the Isles of Scilly, whereas cultivars with Tazetta parentage (e.g., ‘Têteà-Tête’)
may be damaged by low temperatures in eastern England. Data are
available on the cold tolerance of narcissus cultivars, although there are some discrepancies
between studies, perhaps because of the different experimental techniques
used (van der Valk, 1971; Sakai and Yoshie, 1984).
An annual rainfall of about 100cm is considered ideal for narcissus growing.
Evenly distributed rainfall favours crop growth, especially in April to June when
the bulb is growing rapidly, and also facilitates bulb planting and lifting. In
appropriate climates, the availability of irrigation water should be considered.
Waterlogging reduces crop growth, although narcissus are not specially prone to
damage and can tolerate waterlogging if the water is well aerated (Gibson, 1935).
However, wet soils assist the spread of stem nematode in the soil water and in
waterlogged furrows. Growing in light sandy soil with a controlled water table is
the ideal bulb-growing environment, except that the spread of nematodes is favoured.
In windy situations crops may be flattened, reducing yields. MacKerron and
Waister (1975) investigated the effects of shelter on narcissus performance, and
concluded that reducing the wind run from 164 to 118 km/day was probably not
economic for increasing yields.
Topography
Large flat fields are the most economic to farm, while small, sloping fields present
a number of practical problems (Figure 4.2). Warm sites, such as south-facing