Narcissus and Daffodil

82 G.R. Hanks
Planting date
The practice of planting narcissus bulbs soon after HWT has been mentioned
above, and, since the date of HWT is dependent on the stage of the crop, this also
governs the date of planting. Planting immediately after HWT, in August or early-
September, means that the bulbs are planted into relatively warm soil, increasing
the likelihood of infection by the base rot fungus when the roots are erupting from
the base of the bulb (Gregory, 1932; Hawker, 1935). Dutch recommendations, and
earlier recommendations for the UK, are to plant narcissus bulbs in (late-)September.
It is usual to plant cultivars in the same order in which they received HWT. In
one-year-down growing, there is a steady decline in bulb yield when bulbs are
planted later than September. One study showed yields of 120% from September
planting and only 63% from December planting (Wallace and Horton, 1935),
although in another trial (Allen, 1938) significant yield loss did not occur until
planting was even later. In two-year-down growing, however, poor growth in the
first year would be compensated by better growth in the second.
Planting density
The rate of planting will depend on the vigor of the cultivar, bulb price, the
percentage bulb weight increase and size of bulbs required, and the growing
system adopted. In the UK, narcissus bulbs for two-year-down growing are often
planted at densities between 12.5 and 17.5 t/ha. A planting density in the lower
range would be used where vigorous bulbs were being planted, where a high rate
of increase was required (for example, where bulking an expensive cultivar), or
where large bulbs were required; a high density could be used, for example, when
growing a cheap cultivar where the requirements were a reasonable rate of
increase coupled with reducing land and labor requirements, or where a good
yield of smaller grade bulbs was needed. Higher planting rates are more economic
of land and labor: the preferred planting rate is the one which gives the best
financial returns, rather than the greatest yield (Rees, 1972, 1975; ADAS, 1976).
The effects of planting density and planting grade in ridges were investigated by
Rees (1972) in eastern England. For smaller planting grades, the optimum densities
were above the highest used in the trial. For larger grades, there were large differences
in optimum densities and financial returns between years, and over three
years the mean optimum densities were 42 and 27 t/ha for 10/12 and 12/14 cm
grade bulbs, respectively, considerably higher than the planting rates used commercially.
Figure 4.6 shows the profitability for the one-, two- and three-year
growing of small offsets and large DN bulbs grown in ridges in south-west
England at a range of planting densities. Experimental work in Lincolnshire and
Cornwall indicated that planting rates up to 22.5 t/ha could be profitable where a
high production of saleable (middle grade) bulbs was required. Higher planting
densities lead to longer stems and increase crop support on windy sites, so are useful
where the flower crop is important. For growing narcissus on a one-year-down
system, Dutch planting rates vary from 14 t/ha for vigorous, small offset planting
material, to 35 t/ha for large ‘mother bulbs’ where splitting to more saleable grades
of bulbs is desired. Dwarf narcissus such as Cyclamineus cultivars are usually
planted at about half the density of standard cultivars.