Bulletin 312 August, 1937
UNIVERSITY OF FLORIDA
"AGRICULTURAL EXPERIMENT STATION
WILMON NEWELL, Director
EASTER LILY FLOWER PRODUCTION
By WILLIAM B. SHIPPY
Fig. 1.-Side view of the beds where differences in growth between
"warm" plats (Plats 6 and 13) and "cool" plats (Plats 11, 14, and 15)
are quite distinct. The reduced size of plants in cool plat 11 is particularly
noticeable. Plants in the cool plats are mostly second crop, the first crop
having matured during December and January.
Bulletins will be sent free to Florida residents upon application to
AGRICULTURAL EXPERIMENT STATION
EXECUTIVE STAFF BOARD OF CONTROL
John J. Tigert, M.A., LL.D., President of Geo. H. Baldwin, Chairman, Jacksonville
the University Harry C. Duncan, Tavares
Wilmon Newell, D.Sc., Director Thomas W. Bryant, Lakeland
H. Harold Hume, D.Sc., Asst. Dir., Research R. P. Terry, Miami
Harold Mowry, M.S.A., Asst. Dir., Adm. J. T. Diamond, Secretary, Tallahassee
J. Francis Cooper, M.S.A., Editor
Jefferson Thomas, Assistant Editor BRANCH STATIONS
Clyde Beale, A.B.J., Assistant Editor
Ida Keeling Cresap, Librarian NORTH FLORIDA STATION, QUINCY
Ruby Newhall, Administrative Manager
K. H. Graham, Business Manager L. 0. Gratz, Ph.D., Plant Pathologist in
Rachel McQuarrie, Accountant Charge
R. R. Kincaid, Ph.D., Asso. Plant Pathologist
J. D. Warner, M.S., Agronomist
MAIN STATION, GAINESVILLE Jesse Reeves, Farm Superintendent
AGRONOMY CITRUS STATION, LAKE ALFRED
W. E. Stokes, M.S., Agronomist** A. F. Camp, Ph.D., Horticulturist in Charge
W. A. Leukel, Ph.D., Agronomist John H. Jefferies, Superintendent
G. E. Ritchey, M.S., Associate* W. A. Kuntz, A.M., Assoc. Plant Pathologist
Fred H. Hull, Ph.D., Associate Michael Peech, Ph.D., Soils Chemist
W. A. Carver, Ph.D., Associate B. R. Fudge, Ph.D., Associate Chemist
John P. Camp, M.S., Assistant W. L. Thompson, B.S., Asst. Entomologist
Roy E. Blaser, M.S., Assistant Walter Reuther, B.S., Asst. Horticulturist
ANIMAL HUSBANDRY EVERGLADES STATION, BELLE GLADE
A. L. Shealy, D.V.M., Animal Husbandman** J. R. Neller, Ph.D., Biochemist, Acting in
R. B. Becker, Ph.D., Dairy Husbandman Charge
L. M. Thurston, Ph.D., Dairy Technologist R. N. Lobdell, M.S., Entomologist
W. M. Neal, Ph.D., Asso. in An. Nutrition F. D. Stevens, B.S., Sugarcane Agronomist
D. A. Sanders, D.V.M., Veterinarian Thomas Bregger, Ph.D., Sugarcane Physiologist
M. W. Emmel, D.V.M., Veterinarian G. R. Townsend, Ph.D., Assistant Plant
N. R. Mehrhof, M.Agr., Poultry Husbandman Pathologist
W. W. Henley, B.S.A., Asst. An. Husb.* R. W. Kidder, B.S., Asst. Animal Husbandman
W. G. Kirk, Ph.D., Asst. An. Husbandman Ross E. Robertson, B.S., Assistant Chemist
R. M. Crown, B.S.A., Asst. An. Husbandman W. T. Foresee, Ph.D., Asst. Chemist
P. T. Dix Arnold, M.S.A., Assistant Dairy B. S. Clayton, B.S.C.E., Drainage Engineer*
L. L. Rusoff, M.S., Asst. in An. Nutrition SUB-TROPICAL STATION, HOMESTEAD
Jeanette Shaw, M.S., Laboratory Technician
H. S. Wolfe, Ph.D., Horticulturist in Charge
CHEMISTRY AND SOILS W. M. Fifield, M.S., Asst. Horticulturist
R. V. Allison, Ph.D., Chemist" Geo. D. Ruehle, Ph.D., Associate Plant
R. W. Ruprecht, Ph.D., Chemist Pathologist
R. M. Barnette, Ph.D., Chemist BROOKSVILLE
C. E. Bell, Ph.D., Associate W. CENTRAL FLA. STA., BROOKSVILL
R. B. French, Ph.D., Associate W. F. Ward, M.S., Asst. An. Husbandman
H. W. Winsor, B.S.A., Assistant in Charge*
ECONOMICS, AGRICULTURAL FIELD STATIONS
C. V. Noble, Ph.D., Agricultural Economist**
Bruce McKinley, A.B., B.S.A., Associate Leesburg
Zach Savage, M.S.A., Associate M. N. Walker, Ph.D., Plant Pathologist in
A. H. Spurlock, M.S.A., Assistant Charge
W. B. Shippy, Ph.D., Asso. Plant Pathologist
ECONOMICS, HOME K. W. Loucks, M.S., Asst. Plant Pathologist
J. W. Wilson, Sc.D., Associate Entomologist
Ouida Davis Abbott, Ph.D., Specialist** C C. Goff, M.S., Assistant Entomologist
ENTOMOLOGY Plant City
J. R. Watson, A.M., Entomologist" A. N. Brooks, Ph.D., Plant Pathologist
A. N. Tissot, Ph.D., Associate Cocoa
H. E. Bratrey, M.S.A., Assistant a Pathologist
A. B. Rhoads, Ph.D., Plant Pathologist
G. H. Blackmon, M.S.A., Horticulturist and A. H. Eddins, Ph.D., Plant Pathologist
Acting Head of Department
A. L. Stahl, Ph.D., Associate Monticello
F. S. Jamison, Ph.D., Truck Horticulturist Sam O. Hill, B.S., Asst. Entomologist*
R. J. Wilmot. M.S.A., Specialist, Fumigation Br
R. D. Dickey, B.S.A., Assistant Horticulturist David G. Kelbert, Asst. Plant Pathologist
PLANT PATHOLOGY Sanford
B. T l, P.D. Pant Pat is** E. R. Purvis, Ph.D., Assistant Chemist,
W. B. Tisdale, Ph.D., Plant Pathologist* Celery Investigations
George F. Weber, Ph.D., Plant Pathologist
R. K. Vorhees, M.S., Assistant Lakeland
Erdman West, M.S., Mycologist E. S. Ellison, Meteorologist*
Lillian E. Arnold, M.S., Assistant Botanist B. H. Moore, A.B, Asst. Meteorologist*
L. W. Gaddum, Ph.D., Biochemist In cooperation with U.S.D.A.
L. H. Rogers, M.A., Spectroscopic Analyst ** Head of Department.
EASTER LILY FLOWER PRODUCTION
By WILLIAM B. SHIPPY
Diseases and Insects .. . .... . ............... 8
Care of Bulbs During Rest Period ................................................................. 4
Time of Flowering a Major Difficulty ........................................ ................. 5
Related Investigations ........ ... ... ................ .......... .. .. ......... 6
Experiments During 1932 ........... .......... ............... ............... ...... 8
Experiments During 1933 ...... .............................. .. ..... ..... ..... ................ 11
Conclusions ......... .... ...................... ............ .. ............. ............ ........ 17
Summary .......... .................. .... .................. ..... .. .............. 18
Literature Citel .............. ... .. ........... ...... ............... ......... 19
Regardless of the fact that soil and climatic conditions in
Florida are well suited to the outdoor culture of Easter lilies
(Lilium longiflorum Thunb.), commercial production of this
plant has remained almost at a standstill. Many attempts have
been made to grow Easter lilies on a commercial basis, but for
the most part these efforts have ended in failure and discourage-
After a careful study of the situation it appeared that there
were three principal causes for this lack of success: (1) Failure
by growers properly to combat diseases and insect pests found
in the field, (2) improper care of the bulbs during the rest
period, with resulting decay and loss of the bulb stock, and
(3) failure of plants to bloom by Easter or before that time,
when the flowers may be marketed profitably.
DISEASES AND INSECTS
A careful inspection of many plantings indicated that losses
caused by diseases and insects were mostly avoidable through
the use of control practices which have been established for
many years and which are followed wherever Easter lilies are
grown commercially. Past experience has shown that many fine
stocks of bulbs, originally healthy, have been undermined and
eventually made worthless by mosaic disease. The character-
istic light-and-dark-green mottling of the foliage, usually ac-
companied by dwarfing and distortion of the stalks and blossoms,
must be recognized by the grower instantly, and upon discovery
infected plants must be removed in their entirety and destroyed.
4 Florida Agricultural Experiment Station
Otherwise, the disease will spread to neighboring plants, will
carry over in the bulbs to the following season, and. very soon
the entire stock of bulbs will be ruined.
Another serious disease is Botrytis blight. This is a leaf spot
or foliage disease which sometimes, under favorable conditions,
blasts the foliage of entire plantings within a few days. Blight
usually makes its appearance during late winter or early spring,
and thereafter is a constant menace to the plants. Injury
from blight may be almost entirely prevented by spraying the
plants frequently with bordeaux mixture or the use of some
other effective copper spray or dust.
Aphids are an important insect pest of Easter lilies in this
State. Ordinarily, aphids are troublesome only when the buds
are first forming, and they can then be easily held in check by
timely applications of a spray containing nicotine and soap.
Aphids not only puncture very young buds, causing an injury
which later results in brown spotting of the flowers, but they
also spread mosaic disease from plant to plant.
Failure to provide against these destructive diseases and in-
sects has proved costly to many Florida growers.
CARE OF BULBS DURING REST PERIOD
A second important cause of loss is improper care of bulbs
during the rest period. Regardless of when dug or how short
a time they are held out of the ground, precautions should be
taken to avoid injury to external tissues. The bulbs should
never be exposed to the sun for more than a few minutes or
allowed to remain uncovered longer than necessary to remove
surface moisture. A satisfactory procedure following digging
is to spread the bulbs in a thin layer for a few hours in some
covered, well ventilated place. They should then be placed in
boxes of a size convenient for handling and covered with sand
which has been thoroughly dried. Powder-dry sand taken from
beneath buildings serves the purpose very well. While dry sand
takes up any excess moisture from the surface of the bulbs, it
likewise reduces water loss from the bulbs. Bulbs so handled,
and held during storage in a place which is fairly cool and has
good ventilation, usually will remain in sound condition through-
out the rest period.
It is realized that occasionally, due to causes not anticipated
or beyond control of the grower, Easter lily bulbs are damaged
so that they begin to mold. Exposure to high temperatures or
Factors Affecting Easter Lily Flower Production 5
excessive moisture are principal contributing factors. In such
instances the use of a disinfectant may become necessary. With
that thought in mind a number of disinfectants were tested
during the period 1930 to 1932 (7)1 to determine their effect
on the bulbs. Materials used for liquid treatments included
bichloride of mercury, Semesan, Ceresan, DuBay 635, Calogreen,
formaldehyde (standard 40 percent solution), and lime-sulfur;
dusts included Ceresan and lime, DuBay 681 and lime, and sulfur-
arsenate of lead. It was found that Easter lily bulbs suffered
little or no injury when immersed in bichloride of mercury
1:1,000 (by weight), Semesan 1:400 (by weight) or formal-
dehyde 1:240 (by volume) for periods up to one hour at least,
and that dipping the bulbs momentarily in lime-sulfur at con-
centrations up to 1:40 (by volume) is likewise non-injurious.
Other materials proved injurious at the strengths employed, the
amount of injury ranging from slight to severe.
TIME OF FLOWERING A MAJOR DIFFICULTY
The third major difficulty encountered in the commercial pro-
duction of Easter lilies in Florida has been their failure to
produce flowers at the proper time. Since time of flowering
is largely determined by favorable growing temperatures, a
condition not subject to control, this has been a discouraging
phase of the lily problem.
Obviously, Easter lily culture can never become a profitable
enterprise until it is possible to market the flowers to advantage.
This means that a large part of the flower crop must be sold
at Easter or before that time. Prices received for flowers after
Easter allow little profit to growers, and in most instances, do
little more than defray shipping costs.
The growing season for Easter lilies in Florida extends approx-
imately from September until June, with the bulk of the flower
crop coming during late April and early May. Hence, heavy
flower production takes place after Easter, as a rule. The ques-
tion therefore exists as to whether the bulbs can be handled
during the summer rest period or the crop managed during
the growing season so as to hasten flowering, and if possible,
concentrate flower production at Easter time.
The generous use of water and fertilizer is the simplest means
of forcing the crop to early maturity and flowering. During
'Italic figures in parentheses refer to "Literature Cited" in the back
of this bulletin.
6 Florida Agricultural Experiment Station
relatively warm seasons, or when Easter comes late, this may
be all that is necessary to have flowers for the Easter trade.
Many florists hold lily bulbs in cool storage for planting under
glass at spaced intervals of time, so as to bring about a con-
tinuous succession of flowers. However, field growers have made
little use of cool storage. Individual efforts to do so have met
with scant success, and practically no detailed experiments have
been conducted to determine the value of cool storage in the
outdoor culture of Easter lilies. As a matter of fact, there has
been no consensus of opinion as to how the bulbs should be
handled during the rest period. This applies not only to the
possible use of cool storage and the timing thereof, but also
to the best time for digging the bulbs, how long they should
be held out of the ground, and just how they should be handled
during the storage period.
In view of this situation, and since a supply of Easter lily
bulbs (strain sometimes referred to as the Florida lily) was
available after concluding the work with disinfectants, it was
decided to vary procedures for handling these bulbs during the
rest period and to note results. No attempt was made that
year nor in 1933 to take all points into consideration, but rather,
to make a beginning.
A consideration of similar work in this connection is not only
of interest but gives further evidence that the results obtained
in these tests are a normal response to the treatments given.
Griffiths (2, 3) studied the effect of storage temperatures on
daffodil bulbs, using three temperature ranges: 34-36, 45-50,
and 55-62 F. He found that bulbs held in cold storage for
three months during the summer were forced into growth three
weeks or more earlier than those held at ordinary storage tem-
peratures. However, it was found that low storage temperatures
had a decided dwarfing effect on the plants, and that these in-
juries were unmistakable even at temperatures as high as
55-620 F. It was further found that varieties differed in their
response to low temperatures. In some cases the forcing period
was shortened; in others, growth and flowering were inhibited.
No decision was reached as to the best storage temperature to
employ for daffodils. However, Griffiths considered this tem-
perature to be at some point between 50 and 65 F., possibly
differing somewhat according to variety.
Factors Affecting Easter Lily Flower Production 7
In studying the effect of storage temperature on Paperwhite
narcissus bulbs, Griffiths and Wright (4) used the following
temperatures: 36, 40, 50, 55, 60, and 700 F. It was found that
bulbs held at 550 F. for six weeks prior to potting during late
September flowered over two weeks earlier than those not re-
ceiving cool storage. While in some tests this temperature
reduced the number of shoots from the bulbs as well as the
number of florets, the treatment was considered practicable if
flowers were needed earlier than they come naturally. It was
found that the Paperwhite narcissus resembled other varieties
of narcissus in that storage of the bulbs at cold temperatures
caused dwarfing. Dwarfing was serious in the case of all lots
stored for the entire season (June to the end of Septeniber) at
temperatures ranging from 360 to 550 F. At 60' there was still
some dwarfing, but after storage at 70' F. normal growth was
The author presented abstracted reports of the experiments
described in this manuscript in 1933 (5) and 1934 (6).
The Bermuda Department of Agriculture (1) reported pre-
liminary tests on the effect of cool storage of Easter lily bulbs.
Of 100 bulbs harvested during the summer, 20 were planted on
September 18. The remaining 80 bulbs were left in the box of
sand, which was placed in storage at 370 F.. At monthly in-
tervals following, lots of 20 bulbs each were removed from
storage and planted. Emergence was recorded as that date when
half the plants showed above the soil and time of flowering
when half the stems bore at least one open flower. It was found
that the various lots receiving warm storage only and cool stor-
age ranging from one to four months emerged respectively in
9, 6, 5%, 5, and 51/2 weeks after planting; similarly, they flow-
ered in 30, 23, 20, 19, and 16 weeks after planting. The lot
receiving one month cool storage (September 18 to October 19)
was actually the first to flower, and even the lot cool stored
two months and planted on November 19 flowered before the
warm storage lot planted on September 18. The number of
flowers decreased with increasing lengths of the storage period.
From these tests it was considered likely that one month's stor-
age in the cold atmosphere was almost as effective in stimulating
early flowering as a longer period. The suggestion was made
that Easter lily bulbs dug in July, held at 370 F. during August,
and planted in September might be expected to flower about
8 Florida Agricultural Experiment Station
seven weeks earlier than those held from July to September in
Townsend and Lobdell (8) kept Easter lily bulbs in a house-
hold refrigerator from July 22 until September 2 and then
planted them. Plants from these bulbs made quick growth,
began blooming on November 14 and continued to bloom for
more than a month. The stalks died back during January, and
later a second crop of stalks was formed which flowered in May.
Plants from bulbs which did not receive cool storage grew much
more slowly, and did not begin to flower until Easter.
EXPERIMENTS DURING 1932
In 1932, all Easter lily bulbs were dug on August 1 and were
held at prevailing temperatures for a period of 13 days before
further treatment. At the end of that time 600 bulbs having
a diameter of 1 to 11/2 inches were selected for the tests. These
were divided into 12 lots of 50 bulbs each, two lots to be used
for each of six different methods of treatment.. The six treat-
ments were as follows: (1) Planted at once, (2) given 44 days
additional storage at outdoor temperatures before planting, (3)
given 21 days cool storage (40 F.) and planted, (4) given 34
days cool storage, (5) 51 days cool storage, and (6) 65 days
cool storage. So far as temperature is concerned these treat-
ments were essentially as follows:
Treatment 1. Warm temperatures only.
Treatment 2. Warm temperatures only.
Treatment 3. Cool temperatures 21 days.
Treatment 4. Cool temperatures 34 days.
Treatment 5. Cool temperatures 51 days.
Treatment 6. Cool temperatures 65 days.
During storage all bulbs were covered with dry sand. Warm
storage was provided by the space beneath the laboratory build-
ing which was both protected from the weather and well ven-
tilated. Cool storage was provided by the refrigeration facilities
of the Leesburg Municipal Plant.
Following the treatment all bulbs were planted similarly in
beds of Norfolk fine sand, duplicate lots being planted in separate
beds. Depth of planting was approximately four inches and
bulb spacing about 8 or 9 inches each way.
Factors Affecting Easter Lily Flower Production 09
Time of Plant Emergence.-Cool storage (at 40 F.) for
periods of approximately one month or more hastened bulb
sprouting and resulted in early emergence of the plants. Twenty-
one days of cool storage proved insufficient to bring about these
effects. Whether the bulbs exposed to warm temperatures only
were left in the field continuously (briefly lifted in this case to
remove the bulb increase) or held for a rather extended time
out of the ground made no difference in time of emergence of
Growth of Plants.-It soon became evident that storage at
400 F. for 30 days or more not only resulted in early emergence
of the plants but caused the plants to make a noticeably more
rapid growth. These differences were quite marked by Jan-
uary 11, at which time height measurements were taken of all
plants. Plants from bulbs receiving 30 days or more of cool
storage averaged considerably taller than those from bulbs re-
ceiving no cool storage. It is further indicated that this growth
acceleration is to some extent, at least, directly proportional to
the duration of the cool storage period. The advanced state
of growth of plants from bulbs receiving cool storage was doubt-
less not due entirely to stimulation by cool storage, but was due
in part to a longer period of growth, since the plants came up
earlier, and to the benefit derived from warmer temperatures
prevailing during the fore part of the period.
At the same time it became apparent that cool storage did
not affect all bulbs in the same manner. There was considerable
variation in time of emergence of plants from bulbs receiving
similar cool storage treatment. At the time height measure-
ments were made this variation was much in evidence. Height
of the plants ranged all the way from 1 to 16 inches. In the
21-day cool storage plats no plants were taller than three inches;
in the 34-day plats a small proportion was taller than three
inches; in the 51-day plats there were fairly uniform numbers
of plants throughout the scale of 1 to 16 inches, and in the
65-day plats the majority of the plants were in the taller sizes.
Prolonged cool storage also resulted in the failure of some
bulbs to sprout, this being pronounced in the case of the 65-day
treatment. On January 11, 26 percent of the bulbs in this lot
had not yet sprouted.
Of course, the greater height of plants in the cool storage
plats at mid-season does not imply that they were taller at
FIG. 2.-EFFECT OF STORAGE TEMPERATURES OF EASTER LILY BULBS ON TIME OF EMERGENCE, HEIGHT OF THE PLANTS AT .
MID-SEASON, AND ON THE PRODUCTION OF FLOWERS.
-----------------, _. __-_..-
Kind and duration of storage periods Percent of plants Percentage flowers by months* Ave. no.
S____ emergence on Jan. 11 flowers
SAugust September October on Oct. 25 (inches) __er bulb
S 10 20 10 20 10 20 __ j Dec. | Jan. | Feb. j Mar. Apr. May June
1 DwwwP------- ---- 0 2.1 99 1 1.1
2 DwwwwwwwwwwwwwwwP- ---- 0 2.8 100 1.7
3 DwwwccccccccP---------- -- 0 2.1 100 1.1
4 DwwwccccccccccccccP---- ------E 23 3.2 5 11 6 61 16 1 1.3
5 DwwwccccccecccccccccccccccP- - -E 36 6.7 23 15 1 26 14 21 1.8
6 DwwwcccccccccccccccccccccccccccP-- E 1 7.2 6 70 7 15 2 1.0
Percent of total yield w Warm storage
D Bulbs dug c Cool storage Co
P Bulbs planted .Bulbs in field (essentially warm storage)
Factors Affecting Easter Lily Flower Production 11
maturity than those developing from bulbs held in warm stor-
age nor that they were more thrifty in any respect. As a
matter of fact, the opposite was true, as will appear later.
Flower Production.-Figure 2 shows both average flower pro-
duction for the various lots and distribution of the flowering
In respect to number of flowers, it was found that duplicate
plats differed a great deal, this being particularly true for the
cool treatments. Averages of the duplicate plats failed to show
the more abundant flower production characteristic of warm
treatments, which was definitely established by the second year's
Figure 2 shows that most of the flower crop was harvested
in April, whereas usually heavy flowering continues well into
May. Due to severe hail injury on April 28, many flowers and
buds were cut then which otherwise would have been harvested
in May. It will be seen that the 34-day cool storage treatment
resulted in about one-fifth of the flower crop maturing ahead of
the regular season of blooming; the 51-day treatment resulted
in about two-fifths of the flowers being produced ahead of time,
and the 65-day treatment resulted in about four-fifths of the
crop coming in advance of the customary season. Treatments
4 to 6 resulted in a distribution of flowering over approximately
six months of the year, and in the case of Treatment 5 the flower
spread was fairly uniform.
EXPERIMENTS DURING 1933
The first season's results were considered of sufficient im-
portance to warrant continuing the work a second year, and it
was decided to increase the number of procedures for handling
bulbs during the summer rest period. July 1 was considered
to be the beginning of the dormant season, since flowering was
then completed and all old tops had died back.
The new schedule of treatments, starting July 6, required that
some bulbs remain undug; others were to be dug and immedi-
ately replanted; others to be dug at 2-weeks intervals through-
out the summer, placed in warm or cool storage for 30 days,
and replanted; and still others to be dug at the beginning of
the rest period and to receive either continuous warm or cool
storage, or to receive periods of both warm and cool storage
for various lengths of time, with cool storage following warm
12 Florida Agricultural Experiment Station
storage in some cases and warm storage following cool storage
in other cases. These various methods of treatment, 22 in num-
ber, are shown graphically in Figure 3. For Treatments 3 to
12, 60 bulbs were used per treatment, being planted in duplicate
plats of 30 bulbs each. For all other treatments 100 bulbs were
used, or 50 bulbs for each plat. Good condition and a reason-
able uniformity in size were the only points taken into account
in selecting the bulbs.
FIG. 3.-EFFECT OF STORAGE TEMPERATURES OF EASTER LILY BULBS ON
TIME OF PLANT EMERGENCE.
t Storage periods and time of emergence
S- July August Septemberl October November December
10 20 10 20 10 20 1 10 20 110 20 1 0 20
1 Not dug-- - - - - - - - E
2 DP------- ---------------E
3 DwwwwwwP --------------E
5 - - -DwwwwwwP - - - - - E
6 - - - -DwwwwwwP - - -- - E
7 - - - - -DwwwwwwP - - - E
8 DccccccccP - - - - - - - E
9 - DececceccecP - - - E
10 -----DcccccceccccP - --E
10 -- - -DcccccccccP - E
11 - - - -DcccceecccP - E
12 - - - - -DccccccccccP - E
13 Dwwwwwwwwwwwwww'wP- --------E
19 DccccwwwwwwwwwwwwwP- - - - - -E
20 DccccccccccwwwwwwwwwwP-------- --E
21 DccccccccecccccccwwwwwwwP- - - - - -E
22 DcccccccccceccccccccccwwwwP- - - E
14 DccccccccccccccccccccccccccP- - E
13 DwwwwwwwwwwwwwwwwP- - -- - -E
18 DwwwwwwwwwwwwwcccccP- - - - - -E
17 DwwwwwwwwwwccccccccccP- -- E
16 DwwwwwwcccccccccccccccccP-- E
15 DwwwcccccccccccccccccccP-- E
14 DccccccccccccccccecccccccecP- -- E
D Bulbs dug w Warm storage
P Bulbs planted c Cool storage
E Emergence Bulbs in field
The different lots of bulbs, placed in small canvas bags to
keep them separate, were placed in deep boxes and covered
with dry sand during the storage period. The space beneath
Factors Affecting Easter Lily Flower Production 13
the laboratory building was again used for warm storage, and
the local municipal plant again provided controlled cool storage.
As previously, all bulbs were planted in beds with similar depth
of planting and spacing.
Time of Plant Emergence.-Figure 3 shows the various treat-
ments as well as their effect on time of plant emergence.
In each case emergence of the plants is shown when approx-
imately half the plants appeared above ground, a time when
the differences were quite apparent. In no case did all plants
appear simultaneously, but rather, their emergence extended
over a period of two weeks or more. In general, plants in the
"warm" plats came up more nearly at the same time than those
in "cool" plats. The results given in Figure 3 show that there
was about a month's difference in time of emergence between
the bulbs receiving warm and cool storage. Emergence in the
warm plats was largely confined to the month of November and
the first part of December. In the cool plats emergence began
early in October and continued into December.
It will be noted that cool storage for as short a time as 15
days failed to bring about early emergence of the plants regard-
less of whether applied early or late in the summer. Cool stor-
age for 30 days caused early plant emergence about as well
as storage for a longer period. However, results obtained with
Treatments 20 to 22 indicate that bulbs placed in cool storage
too early in the rest period (July 6 in these instances) require
about double this exposure to bring about a similar stimulating
Growth of Plants.-It will be recalled that when the previous
season's plants were measured on January 11, those from bulbs
given cool storage were considerably taller than the ones from
bulbs held at outdoor temperatures. This showed the advanced
condition at mid-season of plants from bulbs given cool storage,
but gave no indication of comparative size of all groups when
mature. This year's measurements were made on May 5 when
blossoming was at its peak, and therefore serve better to show
comparisons of final growth. These comparisons are shown in
respect to average height of the plants as well as to percentage
of tall plants (Fig. 4).
It will be seen that plants from bulbs receiving only warm
storage were regularly taller at maturity than those from bulbs
given cool storage (also see Fig. 1), the average height of plants
14 Florida Agricultural Experiment Station
being 24 inches and 19 inches, respectively. Not only did plants
in the warm plats average 5 inches taller but they had corre-
spondingly greater breadth, generally had broader leaves of
better color, and were altogether more thrifty. Another way
height differences may be considered is in respect to the per-
centage of plants having stems of good length (over 18 inches).
The warm plats produced about a third more plants with long
stems, the average for all warm plats being 92 percent and for
all cool plats being 59 percent.
FIG. 4.-EFFECT OF STORAGE TEMPERATURES OF EASTER LILY BULBS ON THE
HEIGHT OF PLANTS AT MATURITY (MAY 5).
6 S Kind and duration of storage periods Ave. height Percent
.. of plants plants
July August Septemberl October1 in inches over 18"
10 20 10 20 10 20 10
1 Not dug ---------- 19 72
2 DP------------ 22 81
3 DwwwwwwP--------- 23 92
4 --Dw wwwwP------ 24 100
5 ----DwwwwwwP----- 24 93
6 --------- -DwwwwwwP-- 28 100
7 ---- ---------DwwwwwwP 24 100,
8 DccccccccccP--------- 23 98
9 -- DcccccccccccP ------ 19 60
10 --- -DccccccccccP ---- 17 41
11 ---------DccccccccccP-- 20 83
12 ------ - -DccccccccccP 16 18
13 DwwwwwwwwwwwwwwwwwP- 25 98
19 Dccccwww wwwwwwwwwwwP- 22 85
20 DcccccccccwwwwwwwwwwwP- 21 85
21 DccccccccccccccwwwwwwwwP- 19 59
22 DcccccccccccccccccccwwwwwP- 18 57
14 DcccccccccccccccccccccccccccP- 19 68
13 DwwwwwwwwwwwwwwwwwP- 25 98
18 DwwwwwwwwwwwwwccccP- 21 98
17 DwwwwwwwwwwwwcccccccccP- 15 21
16 DwwwwwwwwcccccccccccceccP- 15 9
15 DwwwwwccccccccccccccccccccP- 18 58
14 DcccccccccccccccccccccccccccccP- 19 68
D Bulbs dug c Cool storage
P Bulbs planted Bulbs in field
w Warm storage
Flower Production.-This year again there was a considerable
difference between duplicate plats in the number of flowers pro-
duced, and the difference was much greater in plats planted
with bulbs receiving cool storage. Average flower production
Factors Affecting Easter Lily Flower Production 15
per bulb planted for the various treatments is shown in Fig-
ure 5. The average number of flowers from bulbs receiving
warm storage was 3.75 per bulb, and the number from bulbs
given cool storage was 2.5 flowers per bulb.
The effect of storage treatment of the bulbs on time of flower-
ing is likewise shown in Figure 5.
It will be seen in Figure 5 that flowering of the plants which
developed from bulbs held in warm storage occurred during
the months of April and May. As usually is the case, the bulk
of the flowers were cut during late April and early May. While
many plants from bulbs given cool storage produced flowers
in advance of this time, the bulk of flowering likewise took
place during April and May.
Attention is first called to the fact that only part of the cool
treatments resulted in any substantial number of early flowers.
In fact, only four treatments gave as much as 20 percent of
the total flower yield before April. These were Treatments 11
(with 32% early flowers), 12 (with 53%), 16 (25%), and 17
(21%). In three of these instances the bulbs had been placed
in cool storage after August 15 and kept there for 30 days.
In Treatment 16, although the bulbs were placed in cool stor-
age earlier (August 5), it required more than the 30-day ex-
posure to bring about a similar effect. The data indicate that
if cool storage is to be effective in bringing about a large pro-
portion of early flowers it must be applied late in the summer,
preferably after August 15.
It will be noted that practically all treatments which induced
early flowering likewise resulted in a considerable number of
flowers appearing in June, a month later than the regular bloom-
ing period. Part of these late flowers were formed on a second
crop of flower stalks. In many instances following winter-
flowering and death of the old tops, one or more new stalks
promptly developed, and these flowered after the normal season
(see Fig. 1).
Bulb Production.-At the end of the season all bulbs were
dug and counted. The plats planted with bulbs given no cool
temperature treatment averaged 4.3 bulbs harvested for every
bulb planted (all sizes included), and the plats planted with bulbs
given cool storage averaged 4.9 bulbs. This difference is not
great enough to be significant. However, in those plats planted
with bulbs stored for 30 days at warm temperatures (Treat-
ments 3-7) an average of 3.8 bulbs was harvested per bulb
FIG. 5.-EFFECT OF STORAGE TEMPERATURES OF EASTER LILY BULBS ON THE PRODUCTION OF FLOWERS.
I Kind and duration of storage periods Percentage flowers by months* Ave. no.
SJuly August Septemberl October ____ per bulb
10 20 10 20 1 10 20 10 -Dec. iJan. Feb. -Mar. Apr. I May June- I
1 Not dug ---------- 7 93 2.8
2 DP ------- 6 94 2.8
3 Dwwww wwP--------- 7 93 2.8
4 --DwwwwwwP------ 20 80 3.3
5 - --DwwwwwwP----- 19 81 3.6 -
6 -------DwwwwwwP-- 1 99 5.4 C"
7 ---------DwwwwvwP 7 93 4.5
8 DcocccccccccP- - - - -16 84 2.8
9 -- DccccceccccccP------ 2 1 42 55 2.0
10 - - DcccccccccccP - - 4 4 5 87 3.2
11 -------DcccccccccP-- 1 26 3 3 56 12 3.7
12 ---------DcccccccccP 36 17 4 43 2.0
13 DwwwwwwwwwwwrwwwwwwP-- 9 91 4.8
19 Dccccw wwwwwrwwwwwwwwP-- 3 97 3.4
20 DccccccccccwwwwwtwwwwwwP-- 21 79 2.9
21 DcccccccccccccccwwwwwwwwP- 38 62 2.4
22 DcccccccccccccccccccwwhwwP- 2 2 2 2 8 56 28 1.9
14 DccccccccccccccccccccccccccP- 9 4 1 52 34 1.9
18 DwwwwwwwwwwwwwwwwwP- 9 91 4.8
18 DwwwwwwwwwwwwwwcccccP-- 17 83 3.0
17 DwwwwwwwwwwwccccccccccP-- 17 3 1 15 54 10 1.8
16 DwwwwwwwwcccccccccccccP-- 2 23 52 23 1.8.
15 DwwtwwwcecccecceccccccccccP- 4 6 60 30 2.1
14 DcccccecccccccccccccccccccP- 9 4 1 52 34 1.9
Percent of total yield w Warm storage
D Bulbs dug c Cool storage
P Bulbs planted Bulbs in field
Factors Affecting Easter Lily Flower Production 17
planted, and plats planted with bulbs receiving similarly timed
cool storage for 30 days (Treatments 8-12) averaged 6.3 bulbs,
making the bulb yield of the cool plats 66 percent greater than
that of the warm plats.
1. Neither the time of beginning nor the duration of a warm
storage period has any appreciable effect on hastening bulb
sprouting or bringing about early emergence of the plants and
2. Cool storage of the bulbs at 40 F., if properly timed and
of sufficient duration, hastens bulb sprouting and results in early
emergence of the plants and early flowering.
3. The period following August 15 is particularly critical.
The rest period of the bulbs is nearly ended, new root formation
frequently taking place during late August and early September,
and thereafter they are increasingly more sensitive to cool stor-
age exposures. The later cool storage is applied or the longer
the cool storage period is extended into the fall (within the
period covered by these tests), the greater will be the effect
on the bulbs and the larger the proportion of early flowers.
4. Because of the danger of early sprouting, it seems advis-
able to place the bulbs in cool storage on August 15, or very
shortly thereafter, and to remove them from cool storage and
plant them not later than October 1.
5. Cool storage treatments which stimulate early emergence
of the plants and early flowering have a detrimental effect on
the bulbs. Degree and manifestation of injury depend on the
timing and duration of the cold period. Cool storage generally
results in smaller, less thrifty plants which produce correspond-
ingly less flowers. Particularly if prolonged, cool storage may
prevent or delay bulb sprouting, or may cause a non-flowering
or "blind" condition of the stalks which develop.
6. The use to be made of cool storage will be influenced by
the market available to the grower as well as by his storage
facilities. It seems indicated that cool storage must be used
by most growers if profits are to be realized. Only the flowering-
sized bulbs should be given cool storage, and it seems inadvis-
able to cool storage any given lot of bulbs two years in succes-
sion. A sufficient number of young bulbs will ordinarily make
blooming size each year so that the cool storage treatment can
be made an annual operation for part of the bulb stock.
18 Florida Agricultural Experiment Station
Attention is called to three principal factors which interfere
with the commercial production of Easter lilies in Florida, the
failure by growers properly to combat diseases and insect pests
found in the field, improper care of the bulbs during the rest
season, and failure of the plants to bloom by Easter or before
that time, when the flowers may be marketed profitably. This
paper deals particularly with procedures affecting the time of
Various methods for handling Easter lily bulbs during the
summer rest period were followed in 1932 and 1933 to determine
if the time of flowering might not be subject to control. Six
procedures were tested the first season and 22 the second.
In 1932, the bulbs were dug on August 1, and thereafter
before planting the various lots received, respectively, warm
storage for 13 and 57 days, and cool storage for 21, 34, 51, and
65 days. It was found that neither of the warm storage treat-
ments nor even the 21-day period of cool storage had any notice-
able effect on hastening the time of plant emergence or the time
of flowering. Thirty-four days or more of cool storage caused
many bulbs to sprout early and hastened plant emergence by
about one month. Plants from stimulated bulbs made rapid
growth and produced many flowers in advance of the usual time,
the proportion of early flowers ranging from 22 to 83 percent.
In addition, cool storage caused the plants to produce a sub-
stantial number of flowers after the close of the customary
In 1933 the tests were begun on July 6 to permit greater
variation of storage procedures and to cover a larger portion
of the rest period. Part of the bulbs were left undug; part
were dug on July 6 and replanted immediately. Other lots were
dug at about two-weeks intervals until early September and
held for 30 days under either warm or cool storage conditions.
Still other lots, dug on July 6, were given cool storage ranging
in duration from 15 to 75 days, the cool storage period in some
cases preceding and in other cases following warm storage for
various lengths of time.
The results again showed that no warm temperature treat-
ment, whether the bulbs were left in the ground or dug at
various times throughout the summer and stored for various
periods, had any effect on hastening growth processes. Also,
15 days of cool storage proved insufficient to hasten bulb sprout-
Factors Affecting Easter Lily Flower Production 19
ing and plant emergence regardless of whether applied late or
early in the rest period. Thirty days or more of cool storage
hastened plant emergence by about one month when applied on
or after July 20, but a substantial number of early flowers re-
sulted from 30-day cold treatments only when applied after
the middle of August. The single greatest percentage of early
flowers was obtained when the bulbs were given cool storage
latest (September 3 to October 4). This is in agreement with
results obtained the previous year-the proportion of early
flowers increased as the cool storage period extended later into
the fall. However, there is danger of delaying too long before
placing in cool storage, as the bulbs may start forming new
roots by late August or early September. For that reason, it
would be preferable to place them in cool storage on August 15,
or very shortly thereafter, and hold them in the cold about
It was found that bulbs held in warm storage produced one-
third more flowers than those given cool storage. However, the
warm treatments had no similar advantage in respect to bulb
increase. In fact, where it was possible to compare 30 days
of warm storage with a similarly-timed 30 days of cool storage,
it was found that the cool plats produced 66 percent more bulbs.
1. Bermuda Department of Agriculture. An experiment on cold storage
of lily bulbs. Agr. Bul. of Bermuda Dept. of Agr. 14: 7: 52-54.
2. GRIFFITHS, DAVID. Notes on daffodil storage tests in 1929. Flor. Exch.
73:5:48, 52; 6: 15. 1930.
3. Additional notes on storage of daffodils in 1929. Flor.
Exch. 73: 10: 13, 55. 1930.
4. GRIFFITHS, D., and R. C. WRIGHT. Effect of storage temperature on
date of flowering. Jour. Hered. 23: 467-470. 1932.
5. SHIPPY, WILLIAM B. Ann. Rept. Fla. Agr. Expt. Sta., p. 116. 1933.
6. Ann. Rept. Fla. Agr. Expt. Sta., p. 74. 1934.
7. Treats lily bulbs with disinfectants to eliminate decay.
Flor. Rev. 73: 1888: 13-15. 1934.
8. TOWNSEND, G. R., and R. N. LOBDELL. Ann. Rept. Fla. Agr. Expt.
Sta., pp. 118-120. 1936.