Classroom lecture on poinsettia crops

1. Everything
You
Always
Wanted
to
Know
about
Poinse9as*
*
But
were
afraid
to
ask…

2. What
you
NEED
TO
KNOW
about
poinse5a
flowering:
• Poinse9as
ini?ate
flowers
when
days
become
shorter
than
nights.
In
the
Northern
Hemisphere,
this
day
length
condi?on
naturally
occurs
during
mid
to
late
September.
• Once
short
days
begin,
it
is
important
that
nights
con?nue
to
get
longer
for
bracts
to
form
color.
During
this
development
stage
of
the
poinse9a,
if
nights
get
shorter
rather
than
longer
the
flowering
will
be
disrupted
and
plants
will
fail
to
flower.
• The
phase
of
growth
prior
to
flower
ini?a?on
is
referred
to
as
vegeta?ve
growth,
while
the
flowering
stage
is
known
as
the
reproduc?ve
phase.
• The
flowering
response
?me
is
the
?me,
usually
in
weeks,
required
for
the
plant
to
develop
to
a
mature,
salable
flowering
plant
from
the
date
of
flower
ini?a?on.
This
assumes
all
growing
condi?ons
are
“normal”
for
the
crop.

3. Poinse9a
Crop
Scheduling
• Schedule
flowering
response
?me
for
op?mum
development.
•
Start
with
the
desired
flower
maturity
date
(Dec.
1)
and
work
backwards
using
the
flowering
response
?me
(for
these
cul?vars,
8
and
8.5
weeks)
to
determine
when
the
crop
needs
to
ini?ate
flower
in
order
to
be
ready
for
sale
at
the
appropriate
?me.

4. Vegeta?ve
Growth
Requirements
Vegeta?ve
Growth
Requirements:
Calculate
vegeta?ve
growth
requirements
based
on
the
finished
height
and
flower
ini?a?on
dates.
In
order
to
calculate
vegeta?ve
growth
requirements
the
grower
must
be
aware
of
when
a
cul?var
ini?ates
flowers
so
that
pinching
can
be
scheduled
accordingly.
A
properly
scheduled
pinch
assures
plants
will
have
enough
?me
between
pinch
and
flower
ini?a?on
to
form
enough
leaves
to
achieve
the
desired
finished
height.
Reduced
?me
between
pinch
and
flower
ini?a?on
will
result
in
shorter
plants.

5. Pinching
• The
?me
needed
for
vegeta?ve
growth
is
based
on
desired
size,
geographic
loca?on,
and
vigor
of
each
cul?var.
• Each
cul?var
has
a
different
natural
growth
poten?al
so
more
or
less
?me
between
pinch
and
flower
ini?a?on
is
required
based
on
natural
vigor.
• Plants
in
larger
pots
require
more
?me
between
pinch
and
flower
ini?a?on.
Geographic
loca?on
is
also
important
because
naturally
higher
light
and
warmer
temperatures
will
result
in
more
vegeta?ve
growth.
Growers
in
southern
climates
will
find
that
less
?me
is
necessary
between
pinch
and
flower
ini?a?on
to
achieve
adequate
size
while
growers
in
northern
climates
will
find
that
more
?me
is
required.
The
charts
provided
(Table
2)
suggest
the
produc?on
?me
for
various
forms
based
on
loca?on.

6. How
to
Pinch
Poinse9as

7. Understanding
Photoperiodic
Response
Poinse5as
are
classified
as
short-­‐day
(long-­‐night)
plants
that
ini?ate
flowers
when
the
day
length
is
reduced
to
a
cri?cal
amount
of
?me,
12
hours
and
20
minutes.
This
occurs
around
September
20
to
25,
during
the
fall
equinox.
Photoperiod
Manipula?on
Requirements:
If
the
desired
cul?var’s
natural
finish
date
based
on
flower
ini?a?on
date
and
response
?me
do
not
match
with
desired
finish
dates
then
photoperiod
manipula?on
must
be
used.
To
force
earlier
finish,
black
clothing
must
be
used
to
ini?ate
flowers
early.
Determine
black
cloth
start
?me
by
subtrac?ng
response
in
weeks
from
the
desired
finish
date
(Dec.
1
–
about
8
weeks
for
our
cul?vars).
h^p://www.greenhousegrower.com/video/plant-­‐culture/v-­‐understanding-­‐photoperiodic-­‐
response/
Ligh?ng
and
Photoperiod:
Light
intensity
for
growing
quality
poinse9as
should
be
3,500
to
4,500
fc
for
cul?vars
with
dark
green
foliage
and
5,000
to
6,000
fc
for
cul?vars
with
medium
green
foliage.
We
will
add
ligh?ng
from
about
Sept.
11
to
Sept.
30.
Shade
cloth
is
generally
required
in
the
south
for
reducing
greenhouse
temperatures.
A
30-­‐40%
shade
cloth
can
be
used
un?l
October
1
without
affec?ng
plant
quality.
If
possible,
reduce
light
intensity
to
2,000
fc
aher
primary
bracts
are
fully
colored
and
secondary
bracts
are
almost
mature
to
prevent
fading.

8. Ligh?ng
and
Black
Cloth
• Some
cul?vars
ini?ate
flowering
prior
to
the
cri?cal
day
lengths
and
should
be
lighted
with
night
ligh?ng.
(We
will
not
need
to
do
this.)
• If
the
schedule
for
a
cul?var
requires
the
start
of
short
days
before
those
naturally
occurring,
pull
black
cloth
over
the
plants
from
5
p.m.
to
8
a.m.
at
the
appropriate
?me
of
year,
depending
on
the
cul?var
and
geographic
loca?on.
• 14-­‐hour
nights
should
be
provided
using
black
cloth.
We
will
be
doing
this
from
about
Oct.
6
un?l
about
Nov.
5.
• For
later
finishing,
ligh?ng
to
extend
the
day
length
is
used
to
delay
flower
ini?a?on.

9. Our
Schedule
• We
will
add
ligh?ng
from
about
Sept.
11
to
Sept.
30.
• 14-­‐hour
nights
should
be
provided
using
black
cloth.
We
will
be
doing
this
from
about
Oct.
6
un?l
about
Nov.
5
or
so,
from
5:00
p.m.
to
8:30
a.m.
Add
ligh?ng
9/11
to
9/30
Sept.
3
Sept.
22
9/3:
Add
shade
cloth;
add
fer?lizer
when
watering.
Oct.
6-­‐Nov.11
Dec.
8
Pinch
Black
cloth
Dec.
1
Taper
off
fer?lizer

10. • Add
Poinse5a
Schedule
-­‐
Es?mated
shade
cloth
on
Sept.
3;
add
ligh?ng
from
about
9/11-­‐9/30
• Add
15-­‐5-­‐15
fer?lizer
when
watering:
3.38
oz.
(98.52
g)
conc./gal.
water
for
1:16
Hozon
• Pinch
on
Sept.
22
• Black
cloth
starts
about
Oct.
6
un?l
Nov.
5
• Be
vigilant!
Look
for
any
signs
of
stress,
pests
(whitefly),
and
diseases
• Sale
date
around
Dec.
8

11. Growing
Guidelines

12. Vegeta?ve
Growth
Requirements
based
on
geographic
loca?on

13. Vegeta?ve
Growth
Adjustments
Based
on
Vigor

14. Establishing
Requirements
for
Various
Sizes

16. Poinse9a
Temperatures
v November-­‐
Drop
night
temperatures
to
55-­‐
60°F
(12-­‐16°C).
Do
not
drop
temperatures
below
55°F
(12°C).
Flower
development
will
not
progress
below
50°F
(10°C)
and
chilling
injury
may
occur.
v On
sunny
days
allow
the
greenhouse
to
warm
to
75-­‐80°F
(24-­‐26°C)
to
offset
cold
nights.
On
cloudy
days
maintain
75°F
(24°C).
The
goal
is
to
achieve
an
average
daily
temperature
of
65°F(18°C).
v Mid
November
to
December-­‐
Plants
are
mature
and
ready
to
ship.

17. • Media
for
growing
poinse9as
should
be
on
the
coarse
side
and
excep?onally
well-­‐drained.
• The
pH
should
be
5.8-­‐6.4.
• Poinse9as
are
more
suscep?ble
to
calcium
and
magnesium
deficiencies
than
many
plants;
therefore,
we
are
using
a
fer?lizer
with
5%
Mg
and
2%
Ca,
as
well
as
micronutrients,
added.
• FAFARD
MIX
NO.
3-­‐B
is
an
excellent,
general
purpose
mix
containing
peat
moss,
perlite,
vermiculite
and
about
one
fourth
processed
bark.
It
is
recommended
for
flowering
plants,
bedding
plants,
hanging
baskets,
foliage
plants
and
interiorscape
use.
This
is
the
preferred
Fafard
mix
for
flowering
plants.

18. Water
A
dependable
source
of
high
quality
water
is
an
important
considera?on
in
growing
poinse9as.
The
alkalinity
of
the
water
should
not
be
so
high
as
to
drive
the
pH
of
the
medium
above
6.5
or
micronutrient
deficiencies
can
occur.
The
total
soluble
salts
and
presence
of
nutrients
or
toxins
should
also
be
known.
Poinse5as
can
be
watered
overhead
during
early
stages
of
produc?on
but
moisture
on
the
bracts
is
highly
undesirable.
Therefore,
it
is
recommended
that
crops
be
placed
on
an
automa?c
watering
system
at
or
soon
aher
spacing.
We,
however,
have
other
plants
with
different
fer?lizer
needs
on
that
system,
so
we
will
need
to
hand
water
and
use
the
Hozon
siphoner.

20. Fer?liza?on
• Poinse9as
are
generally
heavy
feeders,
especially
during
early
produc?on.
Fer?liza?on
should
begin
as
soon
ader
po5ng
as
possible
depending
on
how
much
starter
nutri?on
has
been
added
to
the
medium.
• Fer?lity
programs
vary
widely
and
may
include
liquid
fer?liza?on
or
liquid
in
combina?on
with
slow
release
fer?lizers.
However,
success
depends
on
raising
the
ini?al
fer?lity
quickly,
then
tapering-­‐off
toward
the
finish
of
the
crop.
• We
will
be
using
a
15-­‐5-­‐15
(N-­‐P-­‐K)
fer?lizer
at
300
ppm
to
start.
N-­‐P-­‐K
is
the
elemental
shorthand
for
the
three
major
nutrients
in
fer?lizers.
“N”
stands
for
Nitrogen,
“P”
stands
for
Phosphate
(P2O2)
and
“K”
stands
for
Potash
(K2O).

21. 15-­‐5-­‐15
Cal-­‐Mag
Fer?lizer
High
nitrate
and
low
phosphate
with
added
calcium
and
magnesium

22. We’ll
start
with
300
ppm
(parts
per
million).
That’s
4.1
oz.
Cal-­‐Mag/gal.
of
concentrate
with
a
1:16
Hozon
siphoner.

23. Our
fer?lizer
program:
• 15-­‐5-­‐15
at
300
ppm
N
(4.1
oz/gal.
with
1:16
Hozon
siphoner)
for
first
4-­‐5
waterings.
Drop
to
200-­‐250
ppm
N
(3
oz./gal.
concentrate)
aher
5th
watering.
• Drop
to
100-­‐150
ppm
N
N
(1.7
oz/gal.
with
1:16
Hozon
siphoner)
in
November.
• Test
and
chart
pH
and
soluble
salts
at
least
every
two
weeks.
• Reduce
nutri?on
in
the
last
few
weeks
of
the
crop.
In
November
and
December,
temperatures
and
light
intensity
are
dropping
and
the
needs
of
the
plant
decrease
as
flowers
develop.
• Many
growers
will
stop
fer?lizing
completely
in
late
November.
Shelf
life
of
poinse9as
is
increased
if
the
media
soluble
salts
is
close
to
zero
at
shipping
(or
sale)
?me.

24. Spacing
Poinse9a
plants
are
ohen
maintained
on
benches,
pot-­‐to-­‐pot
aher
po9ng
and
up
to
the
?me
of
pinch
for
easy
maintenance
and
to
make
the
pinching
task
easier.
However,
they
should
be
placed
at
the
final
spacing
soon
aher
pinching
and
before
plants
begin
to
crowd.
This
increases
the
light
intercep?on
by
the
plants
and
decreases
the
need
for
growth
retardant.
Final
Spacing
for
Pinched
Plants
Pot
size
Cu9ngs/pot
Spacing
(")
Sq.h./pot
6
2
15
x
15
1.5
4
1
8
x
9
.5

44. Pres?ge
Red
from
Rooted
Cu9ngs

46. Finished
Poinse5as