December 2021 - 27

CULTURE REPORT
'Gelato Cranberry'
'Gelato Pink Cuberdon'
TRANSPLANTING 102 CELL
GROWING TIME
4.5-inch pots
6.5-inch pots
10-inch pots and up
Table 1. Finish time based on pot size.
PROPAGATION
Propagation is
straightforward,
typically taking
four to five weeks,
depending on
your growing
region. Stick
unrooted cuttings
into clean, loose
propagation media or
an engineered soil plug, shortly
after receiving. Grow under
mist/fog at 72 to 76° F, treat with
KIBA at 100 ppm and a broadspectrum
fungicide, and utilize
bottom heat to aid in rooting speed
and uniformity.
I always recommend giving URCs just
enough moisture to keep them from wilting,
since excess moisture does not provide any
benefit and typically causes problems. You can
begin reducing heat and mist as callus, and
eventually root initials, develop to begin toning
plants. Light feeding (50- to 100-ppm nitrogen)
regimes while roots develop will avoid excessive
growth or damage due to salts accumulation.
Maintaining an EC around 0.7 to 0.9 and
pH around 5.8 will provide the best results.
Supplemental lighting will also aid in producing a
higher quality crop. A pinch four weeks after stick
or one week after transplant is recommended to
enhance branching and control initial growth.
This could be substituted with a PGR spray, but
rates and chemicals should be trialed before
wide-scale adoption.
FINISHING
Keeping in mind that plants should be grown
at an ADT of 58 to 64° F for best performance,
there are two methods that growers can use
to produce high-quality osteospermum Gelato
plants for finish.
The first way is the simplest way in that plants
are transplanted and then grown as a cool/cold
crop with an initial ADT of 57° F or lower for at
least three weeks. Plants can then grow under
the naturally cool temperatures and finish five
to six weeks later. The advantage is it is easy
to mix these with other cooler temperatureloving
crops like pansies and primula to develop
naturally with the season. This method is best
with small pots and for super energy-efficient
production practices.
The second method needs a bit more
manipulation but allows for a bit more
programmability if there is a specific sales
date or the finish time is earlier than typical.
Transplant unpinched liners, then pinch after
about one week or after roots have grown into
the new soil. Continue growing the plants under
around 62 to 66° F until the plants get close to
finished size, ensuring that vegetative growth is
not too excessive. Then drop the temperatures
to or below 57° F ADT for three weeks to initiate
flowering then return to warmer growing
conditions to finish. Flowering should occur in
five to six weeks. The only caveat is that under
low-light conditions, flower development may be
poor, so supplemental lighting is recommended.
Both methods result in high-quality finished
plants but ensuring that plants are compact,
either via temperature or using plant growth
regulators, is essential as well. The best finishing
temperatures for flower development and growth
control are 58 to 62° F, but if growing warmer
PGRs should be applied to maintain habit and
prevent growth from exceeding the desired
finished plant size (see Figure 1). Both Bonzi and
Topflor have shown to be effective, but ample
testing for which PGR and at what rate to use
should be done prior to widespread adoption.
PESTS AND DISEASE
Although not typically a major issue, aphids
can be problematic, especially during cold
growing. Thrips and whiteflies can also become
problems as the days get longer, but all can be
managed easily if caught early and preventatively
treated. Root and stem diseases, as well as
botrytis, can also be present, but good cultural
controls like proper water management and
maintaining good airflow are typically sufficient
to prevent major problems. Active and consistent
scouting should be done as part of an overall
integrated pest and disease management
program.
TIMING
Scheduling osteospermum can be challenging.
Trialing and testing has shown it is approximately
three to four weeks from visible bud (3 to 4 mm
long) to an open flower with an ADT of 68° F.
This can take longer if growing cooler, but the
table below outlines a basic schedule if using the
fist growing method.
Bart Hayes is sales manager for Westhoff and can be
reached at bart.hayes@westflowers.de.
GREENHOUSE PRODUCT NEWS 27
8-10 weeks
10-12 weeks
10-14 weeks
RECOMMENDED
PLANTS PER POT
1
1-2
3-5
December 2021

Table of Contents for the Digital Edition of December 2021
