Narcissus and Daffodil

Production of Narcissus bulbs 79
usually, however, interest has centred on the cool storage of bulbs before planting
as a means of advancing (or ‘forwarding’) field-grown cut-flowers. In south-west
England, ‘pre-cooling’ narcissus bulbs for 2–6 weeks at 9 °C before planting gives
flowers earlier and over a longer period, although the flowers may be of poorer
quality and subsequent bulb yield is reduced (Rees and Wallis, 1970; Rees, 1972;
ADAS, 1982d). The optimum treatment for advancing flowering was 6 weeks at
9 °C, with no advantage of using longer or colder treatments or of augmenting the
treatment by covering the growing crops with polythene film (ADAS, 1982c; Flint,
1983). Flowering dates 8–28 days earlier than untreated controls were reported in
these studies. Cocozza (1972) investigated pre-cooling before planting bulbs
outside in Italy, successfully using a treatment at 3 °C for up to 6 weeks. In France,
Le Nard (1975) reported that flowers were obtained 30–45 days earlier than from
untreated bulbs, by warm storage (7 days at 34 °C) followed by cooling (8 weeks at
9 °C) and covering rows with a narrow polythene tunnel. To produce late outdoor
flowers, bulb storage at 20–26 °C from August to October has been investigated,
but this delayed flowering by less than a week (ADAS, 1972). Tazetta narcissus
can be warm-stored over winter for planting in spring (see under Production of
Tazetta Narcissus).
While most interest in these procedures relates to optimising crop growth and
producing earlier flowers, they also offer the possibility of shifting the growth
pattern to one more suited to particular needs, for example to fit a more convenient
or programed production schedule. The effect of temperature on narcissus
growth and development is being studied with a view to developing predictive
models (Hanks et al., 1998b,c). As narcissus growth and yield show marked yearto-year
differences (Rees, 1972; Hanks, 1996a), such crop models would be useful
management tools.
Bulb planting
The main factor to consider is the type of growing system – whether to grow the
bulbs in ridges or beds, and whether to lift bulbs annually (one-year-down growing)
or every two years. Because it is considered more economic, a ‘two-year-down’
growing system in ridges has generally been adopted. Other factors to be considered
include planting date, rate, depth and arrangement; the use of pesticides
at planting, crop covers, cover crops and growing in nets also need to be considered.
Planting and growing in beds or ridges
Bulbs (including narcissus) were traditionally grown in flat beds and were planted
and lifted annually by hand. Bulb planting and lifting are now mechanised. In the
UK, bulb crops are now grown in ridges (as potatoes), and ridges are also used in
the Netherlands where narcissus are grown on heavier soils. Growing bulbs in flat
beds allows better utilisation of the available area, but large volumes of soil have
to be moved in planting and lifting bulbs. Growing in ridges has been adopted
largely on practical grounds, and is useful as it allows sharing of equipment with
potato growing.
Bulbs are planted in ridges using specialised planting machines that typically
feed bulbs from a hopper, planting two rows at a time (Figure 4.4). The planting