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Group Title: Circular
Title: Caladiums as potted and landscape plants
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Title: Caladiums as potted and landscape plants
Series Title: Circular
Physical Description: 5 p. : ill. ; 28 cm.
Language: English
Creator: Evans, M.R ( Michael R )
Wilfret, Gary J
Harbaugh, B. K ( Brent Kalen )
Florida Cooperative Extension Service
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1992
 Subjects
Subject: Caladium -- Florida   ( lcsh )
Plants, Potted -- Florida   ( lcsh )
Plants, Ornamental -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
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Statement of Responsibility: M.R. Evans, G.J. Wilfret, and B.K. Harbaugh.
General Note: Title from cover.
General Note: "June 1992."
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Bibliographic ID: UF00014571
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA7036
ltuf - AJG5660
oclc - 26812827
alephbibnum - 001752703
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June 1992


f' -*, /'f -'" ;' o

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Caladiums As Potted and


Landscape Plants

M.R. Evans, G.J. Wilfret, and B.K. Harbaugh


- L IS


Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida
John T. Woeste, Dean


Circular 1060















































































M.R. Evans is Assistant Professor and Extension Floriculture Specialist, Environmental Horticulture; G.J. Wilfret is Professor of Or-
namental Genetics; and B.K. Harbaugh is Professor of Floriculture, Environmental Horticulture; respectively, Gulf Coast Research
and Education Center, Bradenton, FL 34203.








Introduction
Because of their popularity and versatility, cala-
diums have often been referred to as the geranium
of the South. However, caladiums are not limited
exclusively to the southern United States but can
be used successfully as potted and landscape plants
throughout much of the United States. With im-
proved tuber storage techniques, potted caladiums
may be used nearly year round in both the tradi-
tional florist trade and for interiorscape situations
where additional color is desired.


General information

Caladium tuber quality and cold tem-
peratures
Just as poor quality seed, improper germination
temperature and use of "abused" seedlings can lead
to poor results for seed-grown potted plants, im-
proper handling of caladium tubers at any stage
from harvesting through planting can increase pro-
duction time and diminish the quality of finished
plants.

Caladiums are tropical plants and tubers should
not be stored, shipped, or handled at temperatures
below 65oF. For long-term storage, 70OF is optimal.
Once tubers are cold injured, the damage is irre-
versible. The extent of the cold injury depends not
only upon the temperature but also on the duration
of the low temperature exposure. For example, in-
jury caused by exposure to 60OF for 4 weeks in stor-
age may be similar to injury caused by 5 to 10 days
of exposure at 50F. One or 2 hours at these tem-
peratures may have no apparent effect on subse-
quent growth. Cold injured tubers are slow to
sprout, have fewer shoots, are more prone to dis-
ease, and do not grow as fast as properly handled
tubers. Tubers damaged by exposure to low tem-
peratures are rubbery, while properly handled tu-
bers are firm.

Tuber storage after harvest
After harvest, caladium tubers are washed,
treated with fungicides, and allowed to dry. During
this time, wounds from the harvest process heal
which minimizes the potential for disease develop-
ment. Tubers are then usually stored for at least 6
weeks at 70 80F. This practice is usually con-
ducted by the tuber producer and results in more
rapid and uniform emergence of shoots when the
tubers are planted. Fully cured tubers from the cur-
rent year's crop are usually available in mid-Janu-


ary. Vigor is reduced if tubers are stored for longer
than 16 weeks. Tubers which have not been stored
6 weeks may require 8 weeks from the time of
planting to begin to sprout and an additional 4
weeks to develop to a marketable stage. Tubers
stored at 70oF within the 6 to 16 week ideal period
will sprout and be marketable in only 4 to 8 weeks
from planting. Thus, growers should request infor-
mation from suppliers concerning the date the tu-
bers were dug as well as the storage and shipping
temperatures.

If tubers are purchased which have not been
stored for 6 weeks, then the tubers should be
stored for the required period at 70oF prior to plant-
ing since storage rooms require a minimum of
space, energy and associated costs to maintain at
70OF as compared to a greenhouse. Storage rooms
should have humidity control (75% relative humid-
ity) and air exchange to prevent disease develop-
ment and build-up of ethylene gas.

Tuber size
Although grading systems vary somewhat be-
tween producers, both fancy and lance-leaf cala-
dium tubers are graded according to their diameter
as follows:


Super Mammoth
Mammoth
Jumbo
No. 1
No. 2


4 1/2 inches or larger
3 1/2 to 4 1/2 inches
2 1/2 to 3 1/2 inches
1 1/2 to 2 1/2 inches
3/4 to 1 1/2 inches


Choice of tuber size for a given pot size is impor-
tant. One mammoth tuber per 6-inch pot, one
jumbo tuber per 5-inch pot, one No. 1 tuber per 3 1/
2- or 4-inch pot, one No. 2 tuber per 3-inch pot, or
one No. 2 tuber per cell of a six-pack produces a
marketable plant quickly. Many growers try to use
tubers a grade smaller than normally required.
Howev-- .his can often prove to be a costly mis-
take. To illustrate, if a No. 2 tuber is used in a 4-
inch pot instead of a No. 1 tuber, the first leaves of
the initial sprouts from the smaller tuber will not
yield a plant with the proper pot-to-shoot ratio.
Thus, 2, 3 or 4 weeks extra greenhouse time would
be required for the plant to reach a marketable
size.

In the landscape, the tuber size required de-
pends upon the specific use of the plant in the land-
scape. Jumbo or mammoth sized tubers will give
large robust plants more suitable for areas where
tall plants with large leaves are required. Where








shorter and smaller-leaved plants are desired, such
as in borders, No. 1 or No. 2 sized tubers are best.
However, if the smaller tubers are used, more tu-
bers will be required to fill in a given area.

Terminal bud removal de-eyeing
Tubers with the terminal or dominant bud re-
moved (de-eyed) produce more leaves initially than
tubers planted intact and upright (Fig. 1) and
sprout faster than inverted (planted up-side-down)
tubers. De-eyeing eliminates the apical dominance
of the center bud allowing the lateral shoots to
emerge rapidly. In addition, the leaves of the termi-
nal shoot are usually larger and taller than those
from the lateral shoots. When the terminal bud is
removed, a shorter and more uniform plant with a
fuller canopy results. De-eyeing is not commonly
performed on tubers to be used in the landscape,
However, de-eyeing tubers to be used as borders
will result in shorter and more uniform plants.

De-eyeing is recommended for most cultivars
when using a No. 1 tuber or larger, and No. 2 tu-
bers of the tall cultivars. Most lance-leaf cultivars
will not need to be de-eyed as these cultivars gener-
ally have many uniformly sprouting buds and fill
the pot quickly.

De-eyeing requires only a 1/16 to 1/8 inch deep
cut no larger than 1/4 inch in diameter since the
growing point is on the surface of the tuber. Deeper
cuts increase disease potential and larger diameter
cuts may destroy desired lateral buds. Tubers may
have several similar-sized dominant buds, espe-
cially tubers in the larger grades. As a general rule,





A





/ '



-?Kt -_- W


for tubers with two to four similar-sized dominant
buds, the similar-sized buds are de-eyed. De-eyeing
is generally not required when five or more similar-
sized dominant buds are present on the same tuber
since all these buds will develop and produce a full
pot quickly. However, the tall cultivars should be
de-eyed even with five or more buds to reduce the
height of the finished plant.

Cultivars
There are two distinct types of caladiums: fancy-
leaf and lance-leaf (Fig. 2). Fancy-leaf caladiums
have broad heart-shaped leaves borne on erect peti-
oles. Lance-leaf caladiums have narrow, lanceolate
leaves on short petioles, producing a more compact
or prostrate plant than the fancy-leaved type. Gen-
erally, lance-leaf cultivars produce more leaves
than fancy-leaf caladiums and are ideal for hanging
baskets as well as 4-inch to 5-inch pots.

Although there are over 100 cultivars of caladi-
ums, many of the cultivars should not be grown as
potted plants since they have characteristics result-
ing in a poor quality finished product. Common
caladium cultivars are listed in Table 1 along with
recommended uses and de-eyeing requirements.

Tissue-cultured plant material
Caladiums are commercially propagated through
tissue culture. However, due to variability and the
cost of tissue culture-produced plants, potted cala-
diums are not generally produced from tissue-cul-
tured plants. Tissue-cultured plants are used in the
production of virus-free stock for commercial tuber
production.
Il ,-'\ -:-_. o7-
Ii 4


/4


Figure 1. Preparation of caladium tubers for pot plant forcing. (A) Removal (de-eyeing) of the central or dominant bud(s) will cause
the tuber to produce many small shoots and leaves. (B) Planting the entire tuber will produce a plant with a few large leaves.























Fancy-leaved


Figure 2. Two common types of caladiums based on leaf shape.



Insect and disease problems
Occasionally, root aphids or mealybugs prolifer-
ate on tubers during storage. If insects are detected
on tubers, an appropriate insecticidal dip prior to
planting will control the problem. Mites, whiteflies,
aphids, mealybugs and lepidopterous larvae (cater-
pillars) may attack foliage of plants. However,
these pests usually do not become severe. Since the
turnover of caladiums is rapid, a scouting proce-
dure and application of insecticides on demand is a
better approach than preventive sprays.

Tubers should be examined for rot caused by
fungal organisms or bacteria. Healthy tubers are
firm and the fleshy part of the tuber is bright yel-
low. Internal discoloration, such as brown streaks
or milky-white areas with a pungent odor, is an in-
dication of infection. Severely infected tubers
should be discarded. Preventative drenches of
broad spectrum fungicides, especially those control-
ling pythium and fusarium, are beneficial in pre-
venting tuber damage from fungal organisms.


Forcing caladiums as
potted plants

Growing media
Adequate moisture retention is the most critical
concern with the growing medium. Caladiums, if al-
lowed to wilt, may not only lose leaves but also go dor-
mant. Once dormant, caladiums require additional
time to produce a marketable plant since they do not
re-sprout quickly. Soil mixes should contain a signifi-
cant proportion of peat or other water-holding compo-
nents to produce a soil with high water retention and
have sand or perlite added for drainage (55-65 per-
cent capillary pore space and 4-5 percent noncapillary
pore space).

Planting depth
Roots emerge around each sprout on the tuber.
Since sprouts are only on the top or side of tubers,
roots form primarily on the top and sides of the tuber.
Tubers should be planted upright with 1 to 1 1/2
inches of soil over the top of the tuber to ensure
emerging roots are not exposed.

Prefinished plants
Prefinished plants may be purchased in 4- or 6-
inch pots and are available from approximately
March through May. Prefinished pots usually have 2 -
4 tubers per 4-inch pot and 3 5 tubers in a 6-inch
pot. Prefinished pots are usually shipped after the
leaf sheathes have emerged. Many pot growers find
that purchasing prefinished pots is more economical
than forcing tubers for holidays after Valentine's Day.
Since the prefinished plants are not received until
March or later, the caladium crop does not utilize
space needed for Christmas or Valentine's Day crops.

Fertilization
A maintenance fertilizer program of 5 to 8 pounds
of a slow-release fertilizer such as Osmocote 14-14-14
or Nutricote 13-13-13 per cubic yard of soil at plant-
ing is satisfactory. A liquid fertilization program, be-
ginning when the plants sprout, using 20-20-20 or 20-
10-20 and supplying 400-500 ppm nitrogen once a
week is also satisfactory. If tubers are to be forced
with average temperatures above 70-75F (such as in
heat tents), then the slow-release fertilizer should be
top-dressed at sprouting (1 to 1 1/3 teaspoons per 6-
inch pot) rather than incorporated in the soil before
planting. If the fertilizer is incorporated prior to
planting, the high temperature can cause a rapid re-
lease of the fertilizer salts and result in soluble salt
damage to the plant.








Dolomite should be used to adjust the pH to a
range of 5.5 6.5, and 5 pounds per cubic yard of
single superphosphate should be incorporated into
the soil. These amendments provide sources of cal-
cium, magnesium and sulphur, create a favorable
pH for nutrient availability and reduce problems of
iron toxicity associated with low pH.

Irrigation
Assuming the growing medium has adequate air
space, enough water should be applied to keep the
soil at, or near, the water holding capacity. As pre-
viously mentioned, allowing caladiums to wilt will
result in tubers becoming dormant. Caladiums can
be watered using overhead sprays, "spaghetti tube,"
ebb-and-flow, or capillary mat irrigation systems.
However, since water conservation from 40 -80 per-
cent can be achieved, the latter three methods
should be considered in areas where water is scarce
or expensive.

Light intensity
Light intensity in the growing area can be impor-
tant for two reasons. First, most cultivars do not
develop proper color unless they are grown under
2500 to 5000 footcandles of light. Secondly, light
intensities lower than 2500 footcandles will cause
undesirable stretching of petioles, oversized leaves
for small pots, and unsightly plants which fall over
when handled. There are exceptions since some cul-
tivars require light levels lower than 2500 foot-
candles for optimal coloration including: the white
cultivars Candidum, White Christmas, June Bride,
and White Wing; the pink cultivars Kathleen,
Fannie Munson, and Lord Derby; and the red culti-
vars Frieda Hemple, Postman Joyner, Poecile
Anglais, and Dr. T. L. Meade. In addition, the
dwarf cultivars in the tissue-cultured Honey Bunch
series perform best at 1500 to 2500 footcandles.

Some cultivars perform well under light levels of
5000 to 10,000 footcandles. Among these are the
white cultivars Candidum Junior and Seagull; the
pink cultivars Carolyn Whorton, Rosebud, Mrs. W.
B. Haldeman, Pink Gem, and Lance Whorton; and
the red cultivars Fire Chief and Red Frill..

Forcing temperature
After potting, caladiums should be forced at tem-
peratures averaging at least 70F. Although a night
temperature of 55F for a few hours over several
days can be tolerated, longer durations of cold tem-
peratures or colder temperatures may damage the
plants. Regrowth may occur but will be slow and
usually of poor quality. Day temperatures above


90oF are not favorable, since the rate of emergence
can be reduced. Therefore, a day temperature range
of 70-90oF and a night temperature range of 65-90F
is optimal.

Many growers stack potted tubers in a confined
and easily heated area (such as heat tents) until
sprouting occurs and then space plants in the green-
house. This method reduces heating costs and ap-
pears satisfactory when air exchange is used to pre-
vent build-up of ethylene gas and to prevent tem-
peratures from exceeding 90F. The costs of han-
dling plants twice should be weighed against heat
savings before this method is adopted, especially if
tubers have been stored properly and are ready to
sprout.

Growth retardants
Although growth retardants can reduce the height
of caladiums, the response to a given growth retar-
dant can be variable and is cultivar-dependent. Fur-
ther, growth retardants do not satisfactorily control
the height of the primary leaves from the terminal
bud. Therefore, growth retardant usage is currently
not recommended for use on caladiums.

Shipping
If caladium plants are to be shipped and sold in
other than the production greenhouse, then shipping
and retail outlet temperatures should be maintained
near 700F. Research has shown that storage of
plants at 55"F for 3 days in the dark caused 40 per-
cent of the caladium leaves to turn brown and abs-
cise. Even greater leaf loss occurred with tempera-
tures below 55"F.

Caladiums will not tolerate the cool temperatures
that may be ideal for shipping other potted plants.
Additionally, mass merchandisers often display
plants in produce sections that may be too cold for
caladiums. If caladiums are displayed out-of-doors,
they must be protected from the low night tempera-
tures and windy conditions that occasionally occur in
late spring.


Caladiums in the Landscape

Site Selection and preparation
Caladiums have proven to be excellent bedding
plants for shade and partial shade locations. Al-
though plants develop more intense leaf color in par-
tial shade, they will grow and survive in full sun if
provided adequate water. In addition some cultivars
perform best in full sun locations. Cultivars that tol-








erate full sun conditions and still maintain good color
include the white cultivars Candidum Junior and
Seagull; the pink cultivars Carolyn Whorton, Rose-
bud, Mrs. W. B. Haldeman, Pink Gem, and Lance
Whorton; and the red cultivars Fire Chief and Red
Frill.

The major requirement, once plants are estab-
lished, is an adequate supply of water as caladiums
will not perform well under dry conditions. Soils high
in organic matter are usually excellent. Whatever
the soil type, it should have a high water holding ca-
pacity and yet have good drainage. The soil should be
tilled to a depth of at least 6 inches before planting,
and the soil should be moist. Before planting tubers,
the soil temperature should be at least 650F.

Planting tubers
Tubers should be planted so that 1 to 1 1/2 inches
of soil cover the tubers. The spacing of the tubers de-
pends upon the size of the tuber planted. Generally,
a No. 1 sized tuber should be planted on 12 14 inch
centers. No. 2 sized tubers should be planted on 10 -
12 inch centers. Tubers may be planted closer in or-
der to fill in the bed more quickly. Tubers that are
de-eyed will produce both more shoots and shorter
shoots than tubers that are not de-eyed.

Fertilization and irrigation
Caladiums require a moderate level of fertility.
Many types of fertilizers may be used including or-
ganic materials incorporated prior to planting,
granular fertilizers, slow-release fertilizers, or liquid
fertilizers. Regardless, a balanced fertilizer such as
14-14-14 or 20-20-20 is satisfactory. Plants grown in


warmer climates and on sandy soils will require
higher fertilizer levels than plants grown in cooler
climates or on organic soils and may need supple-
mental applications throughout the growing sea-
son.

Caladiums have a relatively high water require-
ment. If plants are allowed to wilt, foliage loss will
occur and foliar color will deteriorate. However,
caladiums should not be kept constantly wet as tu-
ber rot may develop.

Digging and storing tubers
Caladiums do not tolerate cold temperatures.
When air temperatures drop below 65oF plants will
begin to deteriorate and the foliage will eventually
collapse. Tubers will need to be lifted throughout
most of the continental U.S. except for south-cen-
tral Florida and extreme southern Texas where foli-
age will die but tubers can over-winter. In south
Florida, temperatures may never get low enough to
stop growth and caladiums will survive year round.
Plants grown in the northern half of the U.S.,
where the growing season is short, or that are
grown in dense shade may fail to produce well de-
veloped tubers. In this case it is better to purchase
new tubers and replant in the spring.

When caladiums are lifted, the tubers should be
dug from the soil, cleaned, dried and held in a well
ventilated area at 700F. Temperatures should not
exceed 90"F or fall below 650F. Tubers held for
many weeks may begin to sprout. However, tubers
should not be planted out-of-doors until the soil
temperatures are at least 650F.


Table I. Common Caladium Cultivars, Characteristics, and Appropriate Uses.


Primary Foliage Colors


Uses and Requirements'


Fancy-leaf types
Aaron
Blaze
Candidum
Candidum Junior
Carolyn Whorton
Dr. Groover
Fannie Munson
Festivia
Fire Chief
Florida Cardinal


6-inch pots


white/green
red
white/green
white/green
pink/white/green
pink
pink
pink/green
rose/red
red/green


D
D
D
N
D
0
D '
O0
O0
D


4-inch pots hanging
basket

D

0

D

D
D


Cultivar


bedding
plants
SHD
SHD
SHD
SHD, SUN
SHD, SUN
SHD
SHD
SHD
SHD, SUN
SHD










Cultivar Primary foliage colors Uses and Requirments1

6-inch pots 4-inch pots hanging bedding
baskets plants


Florida Roselight
Florida Sunrise
Frieda Hemple
Gingerland
Irene Dark
Itcapus
John Peed
Jubilee
June Bride
Kathleen
Lord Derby
Miss Chicago
Mrs. Arno Nehrling
Mrs. F.M. Joyner
Pink Beauty
Pink Cloud
Postman Joyner
Red Flash
Rosebud
Scarlet Pimpernell
Tom Tomlinson
White Christmas
White Queen

Lance-leaf types
Caloosahatchee
Clarice
Jackie Suthers
Lance Whorton
Miss Muffet
Mumbo
Pink Gem
Pink Symphony
Red Frill
Rosalie
Sea Gull
Sunset
Sweet Heart
Tropicana
White Wing


pinK/green
white/green/red
red/green
green/red
red
rose/red
red
white/rose
white/green
pink
pink/green
rose/red
white/pink/red
*rose/red
pink/red
pink/green
red/green
red
pink
red/green
dark red
white/green
white/red


rose
pink
white
pink/red
green/red
pink
pink/white
pink/white
red
red
white/green
rose/white
pink
rose/white
white/rose


1Where letters appear under a category, the specific cultivar is suitable for the indicated use. "N" indicates that de-eyeing is
not necessary for the indicated use. "0" indicates that de-eyeing is optional and "D" indicated that de-eyeing is required.
"SHD" indicates that the cultivar should only be grown in the shade and "SUN" indicates that the cultivar performs best in
the sun. Where both "SHD" and "SUN appear, that cultivar performs well under both sun and shade. "HB" indicates that the
cultivar performs well in hanging baskets.



COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T. Woeste,
Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June
30, 1914 Acts of Congress: and is authorized to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding 4-H and youth
publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers
is available from C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida. Gainesville, Florida 32611. Before publicizing Y......
this publication, editors should contact this address to determine availability. Printed 6/92.


HB


D
0

D


,HMU
SHD
SHD
SHD


SHD
SHD
SHD
SHD


u
D
0
N
D
0
D

D
0
0
D
0
0
D
D
D
D
0
D
0
D
D


0
D
D
0
N
0
N
0
N
N
0
N
N
0
0


D
D

D
D


SHD
SHD
SHD
SHD
SHD
SHD, SUN
SHD
SHD
SHD
SHD, SUN


D
D
D


D


D
0
D
D
D
0
0
D
N
0
D
D


HB

HB
HB
HB
HB
HB
HB


HB

HB


SHD
SHD, SUN
SHD, SUN
SHD, SUN
SHD,SUN
SHD, SUN

SHD, SUN
SHD
SHD, SUN
SHD, SUN
SHD, SUN

SHD




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