160 J.E. FAUST, J.M. DOLE, AND R.G. LOPEZ
fluorescence lamps. Stems must be pinched occasionally even if there
is no demand for cuttings, because poinsettias will set a terminal flower
bud under non-inductive long-day photoperiods. This phenomenon is
called “splitting,” and is determined by the number of leaves that form
on a shoot, which is referred to as the long-day leaf number (Evans et al.
1992).
Cold-chain management is as important for poinsettia as it is for gera-
nium; however, poinsettias are typically shipped during the peak month
of July, which tends to be the hottest time of the year in the north-
ern hemisphere. So, the postharvest temperature environment tends
to be more difficult to manage at this time and growers are less likely
to try to hold poinsettia cuttings in the cooler for multiple days prior to
sticking.
In propagation, poinsettias are more prone to wilting than geranium,
and since they are being shipped and propagated during a hotter time of
the year, more attention is paid to moisture management in the posthar-
vest and propagation environments (Wilkerson et al. 2005a; 2005b).
Poinsettia cuttings are wrapped in moistened paper prior to bagging
the cuttings in order to create a high-humidity package. Also, propaga-
tors provide more frequent mist for poinsettia due to lack of drought
tolerance, compared to species such as geranium, coupled with the
extremely high temperatures in the propagation greenhouse in July
and August. Finally, poinsettias are chilling sensitive, so the optimum
cooler temperature is 10◦C.
C. Annuals
Important annual species in the floriculture cutting industry include:
argyranthemum, bacopa, begonia, calibrachoa, coleus, dahlia, fuchsia,
impatiens, lantana, lobelia (Lobelia erinus), osteospermum, petunia,
portulaca, verbena, and dozens of others. The stock-plant-production
methods, postharvest handling, and propagation techniques are very
similar to those for geranium. The main distinguishing factor for annual
species is high cutting yield of the stock plants. Stock-plant growers
can expect to harvest 150 cuttings/m^2 for petunias and as many as 350
cuttings/m^2 /wk for lobelia. This contrasts with the yield of geranium
and poinsettia, which produce<50 cuttings/m^2 /wk.
Propagation of annual species is often complicated by the sheer num-
ber of different species and cultivars that may be in the same propa-
gation space at the same time; thus, it can be difficult providing the
ideal environment for each species. Consequently, propagators will
categorize species and cultivars within a species by their moisture