Pot Mum - Improving Winter Quality

improving winter quality
pot mum
General
Late October through January pot mum plantings for (January
through early April flowerings) are the most difficult to finish
on time and with top quality. The following tips are directed
toward improving pot mum winter quality in the North. They
are suitable for improving winter quality in all regions of North
America, because winter daylight hours are shorter, and light
intensity levels are lower, especially in the northern regions.
Starting Environment Is Crucial
Provide maximum available light. HID (High Density Discharge)
lighting is very helpful. Plant into moist root medium. Soil
temperature should be 68 – 70°F and must be well drained. Apply
300 ppm N and K immediately after planting or sticking cuttings.
Use carbon dioxide injection of 500 to 1,000 ppm. Keep relative
humidity high (90%). Do not allow cuttings to wilt.
Plants Must Be Ready Before Pinching
Roots must reach the sides and bottom of the pot and 1"/
3 cm to 1.5"/4 cm of new shoot growth should occur prior to
pinching. If pinched too soon, it limits the number of lateral
branches that could develop and plants lack fullness. Extra
time may be needed after planting to allow for this proper root
and shoot development in winter-flowering crops, especially in
extra dark weather or crops grown on the ground.
Maximize Light
Low light is a major limiting factor affecting quality in winter pot
mums. Start plants in the highest light area of the greenhouse.
Clean roofs are essential to maximize light transmission. Do
not hang crops which block light over the pot mums. Allow
adequate space during production. Spacing too close early
in the crop may reduce the number of breaks after pinching
because of excessive shading by foliage. Do not allow foliage
to overlap between pots. Use HID lighting of 500 to 800 foot
candles in the North from planting (18 hours daily) until two
weeks after starting short days (up to 11 hours daily).
Provide Enough Long Days
Adding five to seven more long days after pinching often
improves winter quality; especially if winter crops were too
short using less lighting. Short treatment varieties require the
extra lighting in this period.
Carbon Dioxide Injection
Use of carbon dioxide is beneficial during the heating season,
especially in winter when normal ventilation is reduced. It is
also extremely critical when using HID lighting, since carbon
dioxide must be present in quantities that match the light
intensity. With higher light intensities, the normal concentration
of carbon dioxide in the air can limit the rate of photosynthesis.
Injection of 500 to 1,000 ppm is ideal.
Temperatures Affect Timing and Quality
Crop timing is most affected by temperatures from planting
until visible bud. Minimum temperature in this period is
65°F/18°C nights, at plant level. Temperatures lower than that
may significantly delay a crop. Lower night temperatures to
63°F/17°C from visible bud to disbudding and to 60°F/16°C from
disbudding to flowering. A mum crop can not be accelerated by
raising temperatures after visible bud stage.
See chart for lower temperature varieties for Easter flowerings.
Day temperatures should be only O°F/-18°C to 3°F/-16°C warmer
during cloudy days, and 5°F/-15°C to 6°F/-14°C higher in sunny
periods, for better quality plants. Higher temperatures without
higher light weakens plant growth because carbohydrates stored
in the stems are used up in cloudy periods, and are unable to be
replaced without sun.
Conserve carbohydrates for stronger stems, and better flower
color and quality by paying close attention to day temperatures,
and save energy as well.
Bottom Heat
Bottom heat is helpful because it helps dry out media faster,
and allows more frequent feedings.
Less Growth Retardant
Cloudy, cooler days in this period usually cause less variation
between day and night temperatures. This results in less
internode stretch and thus shorter plants. Also, plant growth
is naturally slower in this period. Delaying the first B-Nine
application until new shoots are 3 – 3½"/8 to 9 cm long is
suggested. B-Nine rates should not exceed 2,500 ppm in this
period. The season requires fewer applications. Short varieties
may not even require any chemical growth regulation.

The use of Florel or Ethrel is not recommended for use on
Syngenta Flowers pot mum varieties, especially during the
winter months.
Use of PGRs should be based on variety need.
Improving Keeping Quality
Production under maximum available light and fertilizer
termination two weeks before harvest dramatically improves
consumer keeping quality. Also, allow plants to develop flowers
at least 50% open before harvesting for sale. Keep transport
and storage temperature at 35° – 40°F/2° – 4°C. Do not exceed
seven days for shipping. Higher temperatures and extended
storage or shipping times decrease interior longevity and
increase leaf yellowing.
Use Nitrate-Nitrogen
The majority of nitrogen should be provided in the nitrate form.
Ammonia or urea-based fertilizers produce a softer growth and
deplete plant carbohydrates in this low-light growing period.
Also, since constant fertilization is less frequent in winter,
increase fertilizer rates to 350 to 400 ppm. If the media uses
a good percentage of bark, additional ppm’s maybe needed.
Bark ties up some nitrogen. Growers mixing their own fertilizer
should switch to calcium nitrate and potassium nitrate from
October 15 through April 15. Complete fertilizers that are
formulated to be 50% or more nitrate are best for winter use.
Variety Selection is Important
Many varieties are not suitable for winter and early spring
production in the North.
Based on our winter trials in the North the past few years, we
have put together a select group of varieties for winter. (See
chart on next page.)
These varieties are not only good performers for winter, but can
be grown at 58°F/14°C night temperature (at plant level) in the
growing on area, after leaving the starting area. Those in bold type
are the very best under that growing on temperature regime.
Sample Winter Fertilizers
oz./Gal. Stock
Fertilizer ppm N 1:100 Injector
21-5-20 250 15.9
60% Nitrate 300 19.1
350 22.2
20-10-20 250 16.7
60% Nitrate 300 20.0
350 23.3
15-16-17 250 22.2
53% Nitrate 300 26.7
350 31.1
15-10-30 250 22.2
60% Nitrate 300 26.7
350 31.1
15-0-15* 250 22.2
80% Nitrate 300 26.7
350 31.1
Calcium Nitrate + 250 13.2 Calcium
Nitrate + 9.2
Potassium Nitrate
Potassium Nitrate 300 15.9 Calcium
Nitrate + 11.0
Potassium Nitrate
100% Nitrate* 350 18.6 Calcium
Nitrate + 12.8
Potassium Nitrate
*A separate source of phosphorus is required with
these fertilizers. One option is to inject 1-1/2 ounces
of 75% phosphoric acid per 100 gallons of water to
give 44 ppm phosphorus. Phosphoric acid must be
injected separately from the above fertilizer. Do not mix
phosphoric acid in stock tanks with any fertilizer.

Syngenta Flowers Recommended Pot Mum variety list for
Easter Low Temperature Production (58ºF/14ºC) nightsf
7 wk Type Vigor 8 wk Type Vigor 9 wk Type Vigor
White
Yellow
Pink
Purple
Tahoe 1 Daisy Tall
Olympia 1 Decorative Medium
Ottawa Decorative Medium
Yellow Cupertino 1 Daisy Medium
Covington Decorative Short
Vineland Daisy Short
Deep Presideo 1 Decorative Tall
Spirit Lake Daisy Medium
Winnipeg Quill Medium
Juneau 1 Daisy Medium
Brunswick Daisy Spoon Tall
Trenton Decorative Short
Gainesville 1 Decorative Medium
Vail Decorative Medium
Butterfield Daisy Medium
Chesapeake 1 Daisy Medium
Kingsville Decorative Short
Manhattan Decorative Short
Providence Decorative Short
Dazzling New York Decorative Medium
Golden Gate** Decorative Tall
Chatham Decorative Short
Dark Chatham Decorative Short
New York 1 Decorative Medium
Regal Irvine 1 Daisy Medium
Laporte Daisy Spoon Medium
Regal Lansing 1 Decorative Tall
Coral Current Irvine 1 Daisy Medium
Orange Cupertino Daisy Tall
Bronze Dark Bronze Irvine Daisy Medium
Red
Encino Anemone Spoon Medium
Red Auburn Daisy Medium
Red Irvine Daisy Medium
Tobago Daisy Medium
Harvard Decorative Medium
Pink Sonoma Daisy Medium
Sonoma Daisy Medium
Dark Pomona Deco Medium
Red Sonoma Decorative Medium
1 Recommended varieties *Excellent in small pots and pans **Single stem disbudded pots
f Night temperature in the growing on area with masimums of 68°F/20°C on cloudy days and a sunny day temperature of 72°F/22°C
SYNGENTA FLOWERS, INC., 6899 Winchester Circle, Suite 102, Boulder, Colorado 80301
303 - 415 -1466 I 800 - 344 -7862 (U.S. only) I 303 - 415 -1605 fax I www.syngentaflowersinc.com