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Minnesota Flower Growers Bulletin - January, 1991

Volume 40, Number 1

Environmental Requirements:

Light: Although each cultivar has its own optimum light level, most cultivars perform best at approximately 5,000 footcandles

(1,000

micro

mol

s-1

m-2)

or

in

60%

shade

When planting tubers out-of-doors, tubers should be planted when the soil

temperature is 65OF (18oC) or above.

Water:

Plants

should

be

watered

when

in

Florida

(Conover

and

Poole,

1973).

The

medium begins to dry.

Do not overwater as

'Holland Bulb Forcer's that caladiums should 4,000 footcandles.

Guide' recommends be grown at 3,000-

root and tuber rot will occur. plants should not be allowed irreversible damage may occur.

However, to wilt as Tubers may

Insufficient light results in smaller leaves, reduced plant height, and reduced

become dormant

if

the

medium

becomes dry.

plant quality.

Excessive

reduced

coloration

due

light to

results in increased

chlorophyll (green pigment) Plants may also be stunted and leaves.

production. have smaller

Temperature: Tubers should be stored after

harvest (cured) to promote rapid after planting (see propagation).

sprouting 'Curing'

involves exposing tubers to 9OoF for3 days

then storing tubers at 70-75oF for at least 6 weeks for early forced caladiums or storing

tubers at 70-750F constant temperatures for caladiums forced later in the season.

Most pot plant producers receive tubers that already have been cured by the tuber

producer.

immediately,

If tubers are

they

may

be

not to stored.

be planted Generally,

temperatures of 70 - 80oF (21 - 27oC) are recommended for storage. Relative humidity should be maintained at approximately 75%. Good air circulation should be maintained to prevent build up of undesirable gases and to prevent fugal growth on tubers. A fungicide

dust may also be applied to prevent fungal growth on the tubers. Tubers should never be

stored

below 70oF (21oC).

Optimal

forcing

temperature

for

caladium

is

75-800 F

(24-270 C).

Temperatures can be raised to as high as 9OoF (32oC) to increase the rate of leaf emergence.

However, forcing at 9OoF temperatures reduces root

(32oC) or higher

growth.

Bottom

heat

is

often

beneficial

to

encourage

sprouting. greenhouse

When caladium are with plants which prefer a

in a cooler

temperature, cover to increase the pot

pots with a

clear plastic

temperature

and relative

humidity under the plastic. After leaves emerged, temperature can be lowered to

have 70oF

Fertilization:

Many

types

of

fertilizers are acceptable.

Conover and Poole

  • (1975)

    recommended 6 kg Osmocote (14-14-

  • 14)

    per cubic meter of medium (6 ozkubic

ft) or 1 tsp per inch (15 cm) pot diameter. A constant feed of 100 - 200 ppm nitrogen and potassium weekly has also been used to successfully grow caladium. Superphosphate may be added prior to potting. The pH should be maintained at 5.5 - 6.5. Dolomitic lime may be added to the mix prior to potting to

raise the pH if necessary.

Excess nitrogen may cause undesirable green leaves (due to over production of chlorophyll).

Gases: - A high relative humidity (75%)

is required during storage to reduce tuber

weight loss.

No information is available

on

the affect of C02 on caladium growth.

PrODCiaatiOn - Caladium propagation is

accomplished by tuber multiplication, tissue

culture or by seed. common means of

Tubers are the most caladium propagation.

Tuber propagation is usually conducted in the spring. Pieces of tuber (1 cubic inch) with at least 1 bud are planted in the field in spring. Before planting tuber pieces are soaked in hot

water mature

(122oF) for 30 minutes. and tubers are harvested in

Plants August.

The tubers are placed in drying and then placed in

open containers for a forced air building

for curing (70 - 80oF, 75% RH). results in more rapid sprouting.

Curing After

curing, tubers are dipped in or dusted with a fungicide.

Caladium tubers are graded by the circumference of the tuber. Tuber grades and the respective sizes are shown in Table 2.

(21oC) without plant growth.

any

detrimental

effects

on

3

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