CHICAGO Amencan Bull Company NEW YORK 
The Culture of 
Chrysanthemums, Any Season 
SOURCE: OHIO STATE FLORISTS BULLETIN 
Since publication, in the September, 1950 Bulletin, of 
the year around flowering program of chrysanthemums, 
the introduction of new varieties and refinements of 
culture necessitate the revision which we are present- 
ing now. 
CUT FLOWERS 
The schedule of operations is that of Yoder Bros., 
adapted for the 40° to 45° north latitude (New England, 
New York, Pennsylvania, north half of Ohio, north half 
of Indiana, north half of Illinois, Iowa, Minnesota, Wis- 
consin, Michigan, Washington, and Oregon). For the 
latitude of 35° to 40° north (southern New Jersey, 
Delaware, Maryland, Virginia, West Virginia, North 
Carolina, Kentucky, Tennessee, Southern Ohio, south- 
ern Indiana, southern Illinois, Missouri, Kansas, Colo- 
rado, northern Arkansas, northern Oklahoma, southern 
Nevada, southern Utah, and central California) a slight 
modification of the schedule should be made between 
the dates of July 21 and March 3 only. This modifica- 
tion consists of cutting off one week of long day treat- 
ment or, to state in another way, give short day con- 
ditions one week earlier than is shown in the schedule 
presented here. For more southern latitudes, other 
schedules should be consulted. 
Even though you may not be interested in chrysan- 
themums at all seasons, there is considerable interest in 
the flowering of the mum for specific periods. For ex- 
ample, the production of white, yellow, and light pink 
pompons for the spring months has been very profitable 
for some growers. The schedule can also be used for 
production of standard mums when natural varieties 
are mediocre or poor. This is well illustrated in Decem- 
ber, when Smith’s Late White and Tobin’s Late Yellow 
may be the only varieties available. In this case it is 
quite simple to delay the flowering of the Indianapolis 
group, the Mefos, or the Queens for December to have 
good quality standards for this period. 
CUTTINGS 
The cuttings must be taken from lighted stock plants, 
and it is simplest to buy them from the specialist who is 
doing it. 
LIGHTING 
To prevent formation of flower buds the light in- 
tensity must be 10 foot-candles (F.C.), For an ex- 
tensive area, additional light is best supplied by bulbs 
near the roof of the greenhouse and you should con- 
sult your local light and power company concerning 
the cheapest method of providing the desired intensity. 
For smaller installations the spacing given below will 
be satisfactory for a bench 4 feet wide: 
60-watt bulbs in a reflector, spaced 4 feet apart, 2 to 4 feet 
above the tops of the plants. 
100-watt bulbs in a reflector, spaced 6 feet apart, 2 to 4 feet 
above the tops of the plants. 
200-watt bulbs in a reflector, spaced 8 feet apart, 2 to 4 feet 
above the tops of the plants. 
Lights must be used between August 1 and May 15 
because during this period the day length is short 
enough to cause flower buds to form on some of the 
varieties. 
Results of work by experiment stations and commer- 
cial firms show that best results with lights are secured 
by interrupting the night. Actually, the chrysanthe- 
mum is a “long night” plant rather than a “short day” 
plant. This may appear to be splitting hairs, but flower 
buds can be prevented from forming by interrupting 
the night even though at the same time the day length 
is short. Therefore, begin lighting at 10 p.m. for the 
number of hours shown below: 
Month Hours of lighting per night 
August 2 
September 214 
October 3 
November 4 
December 5 
January 5 
February 4 
March 3 
April 2 
May 1-15 2 
Though manipulation of light to control spray forma- 
tion is feasible, it is too complicated for the grower who 
is not a mum specialist. 
SHADING 
Between September 1 and February 15 the day 
length is short enough to cause flower buds to form on 
all varieties. Therefore it is not necessary to cover the 
plants with black cloth during this period. However, if 
you have a number of houses or benches in mums and 
the lights are not all turned off the same day, then you 
must use black cloth as a curtain between lighted and 
unlighted benches. 
TEMPERATURE 
To insure rapid vegeative growth as well as flower 
bud set, the night temperature must be 60° F. There 
are only a few crops that can be grown with chrysan- 
themums at the 60° F. night temperature during the 
fall, winter, and early spring months. Chrysanthemums 
can be grown with roses, gardenias, and China asters. 
However, stocks, snapdragons, and other cool crops 
cannot be grown with chrysanthemums. Flowers of ex- 
tra fine quality can be produced by gradually lowering 
the night temperature to 50° F. after the flower buds 
are visible. This requires more time than shown in the 
schedule and cannot be practiced where chrysanthe- 
mums in various stages of development are being 
grown in the same house. 
In hot summer weather, black cloth shade should be 
applied late in the afternoon and removed later in the 
morning—this will reduce the heat under cloth. Some 
varieties will not develop properly if it is too warm 
