January 2025 - 50

CULTURE REPORT
Water requirements
Misting should maintain a film of water on the leaves,
but overmisting should be avoided.
Rooting
Root media temperature should be maintained at
73-75° F. Callus formation should be visible by day seven.
Gradually reduce the misting frequency as roots develop.
PGRs
An early PGR application can be beneficial to vigorous
varieties at this stage to avoid stretching.
Finishing
Begin to fertilize as soon as roots begin to form with a
100 ppm N, no-phosphorus formulation.
By day 15, roots should have expanded to the edge
of the cell. Continue toning the crop by increasing air
movement and light intensity. Misting should be greatly
reduced during the day and stopped overnight. PGRs may
be needed on vigorous varieties.
ESTABLISHMENT
If receiving rooted liners, unpack liners immediately
upon receipt and transplant within 48 hours. If
transplanting is delayed, fertilize liners every other day
with 100-200 ppm N. Rinse foliage with clear water to
avoid phosphorus damage and do not allow media to
dry out, as this will increase the probability of future
pythium infections.
Nutrition
Fertilize after transplanting with 200-250 ppm N to
charge the growing media. Rinse leaves with clear water
after fertilizing to avoid phosphorus damage.
Lighting
Light levels should be increased to 4,500
footcandles (19 mols/day) after transplant. Shading
and/or misting should be used at higher light
levels to avoid wilting. Full light is desirable once
plants start rooting out and no longer wilt.
Temperature
Temperature after transplant should be
maintained between 75-85° F during the
day and 70-75° F at night. Once liners
are well-established, temperatures
can be reduced to 70° F (day) and
65° F (night). Cool temperatures
will slow overall growth, while high
temperatures can cause heat delay,
leaf edge burn and foliage distortion.
50 JANUARY 2025 GPNMAG.COM
PGRs
PGRs can be applied if no growth regulators were
applied in propagation or to prevent lateral stretch. If
needed, chlormequat at 500-1000 ppm may be used
based on program needs. Always follow label directions.
Pinching
Ever-branching varieties can be produced without a
pinch to achieve a unique plant habit unlike a traditional
poinsettia. Lateral branching will occur naturally at the
base of the plant while the main shoot will produce a
showy bract on top. Mini bracts will grow along the main
stem and along the lateral stems.
Pinching should take place when roots reach the edge
of the growing container, approximately 10-14 days after
transplant or 4-5 weeks after direct sticking. In general,
the number of nodes remaining should match the finish
container size (i.e., 5-6 nodes for a 6-inch pot). Leaving
too many nodes will encourage weak, horizontal growth
and is not recommended.
VEGETATIVE GROWTH
Spacing pot-tight can encourage V-shaped habits on
some cultivars, but is not needed on naturally V-shaped
habits. Plants should be spaced apart once leaves begin
to overlap.
Fertilizer is recommended at a constant feed of 100200
ppm N from a balanced formulation, including minor
nutrients. Molybdenum and calcium are particularly
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January 2025

Table of Contents for the Digital Edition of January 2025
