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CULTURAL FACTORS AFFECTING CROTON PROPAGATION
C. A. Conover and T. Poole
University of Floiia,.IFAS- --_
Agricultural Researc Center-Apoaka i ,
ARC-A Research RepOrt RH-83-21 "'
Crotons have been popular in tropic dens for centuries, but only in
recent years have they become popular in rIntiLtjvEgenr he mqst popular
croton cultivars commonly available in the U.S through- 6tJi T 1970s, such
as Codiaeum variegatum 'Bravo' and 'Oakleaf' experienced considerable leafdrop
upon placement in an interior environment. During the last 5 to 10 years,
many new varieties have been developed in Europe which tolerate low light
interior conditions. Considerable research has been conducted under European
greenhouse conditions on these cultivars, including stock production,
propagation and factors affecting growth of pot plants (1,2,3).
Although European research is useful to croton growers in the U.S., it
was conducted under light intensities and temperatures that are much lower
than those found in Florida and other croton production areas, except for
winter periods. However, European croton growers are able to produce high
quality crotons with good color under their light conditions because low night
temperatures aid in color development.
Conover and Poole (4) produced Codiaeum variegatum 'Elaine'and 'Norma'
cultivars under 30, 47 and 63% shade and found all acclimatized to interior
conditions, although 30% shade grown plants had slightly more leafdrop. Stock
plants of 'Elaine' and 'Norma' grown in full sun produced slightly more cuttings
than plants under 30% shade, but color was better on shade grown plants (5).
In the same experiment, the highest fertilizer level of 1500 Ibs N/A-year
produced the highest number of cuttings.
The work reported here was initiated to determine whether stock plant
culture influenced cutting quality and rooting ability as well as to examine
effects of fertilization during the propagation period.
Experiments 1 & 2. Both experiments were 2x3 factorials in randomized
block design with 10 replications. Tip cuttings 3 to 4 inches long were
selected from 'Elaine' or 'Norma' (Expt. 1) or 'Craigii', 'Elaine' or 'Norma'
(Expt. 2) stock plants which had been grown under 30 or 47% shade on 1500 Ibs
N/A-year from 18-6-12 Osmocote. Cuttings were directly stuck into 4 inch
square pots containing Florida sedge peat:pine bark:cypress shavings in a
2:1:1 (v:v:v ratio) which had been amended with 7 Ibs dolomite, 11 Ibs Perk
and 2, 4 or 6 lbs of 14-14-14 Osmocote/yd3. Immediately after sticking,
plants were placed under mist (15 sec/30 min) until rooted. Air temperature
within the propagation area ranged between 55 and 1000F, while the propagation
medium was maintained at 75 to 800F (Expt. 1) and 70 to 800F (Expt. 2). Light
intensity during propagation ranged between 1500 and 200 ft-c. After rooting,
plants were placed under 47% shade and watered as needed. Experiment 1 was
initiated March 7, 1977 and Expt. 2, August 14, 1978; both were terminated
after 8 weeks. Both top and root grades were taken for Expt. 1 and root grades
only for Expt. 2. Top grade was measured on a 1 to 5 scale where 1 = poor
quality, 3 = average quality and 5 = excellent quality. Root grade was 1 =
no roots, 3 = 4 to 6 roots up to 2 inches long and 5 = 9 or more roots up
to 4 inches long.
Top grade in Expt. 1 and root grades in both experiments were higher when
cultivars of all cuttings utilized were from stock plants grown under 47%
shade rather than 30% (Tables 1 and 2). These data probably reflect the fact
that these cultivars were developed for the low-light European production area
and are best adapted to lower light intensities. Increasing fertilizer level
of the propagation medium had no effect on 'Norma' in either experiment, or
'Craigii' in Expt. 2 (Tables 1 & 2). Both top and root grades were greater
for 'Elaine' in Expt. 1 with the highest fertilizer level, while root grade
was best at the lowest level in Expt. 2. These data show that cuttings
propagated from 47% shade grown stock plants are of higher quality than those
from stock grown under higher light levels. However, yield of stock plants
grown under higher shade is reduced (5). Some beneficial effects of increas-
ing fertilizer level in the propagation medium were observed, but they were
variable and the highest rate was not always the best.
Experiment 3. This experiment was similar to Expts. 1 and 2, except that
treatments also included cuttings selected from stock plants which had
received 900, 1500 or 2100 lb N/A-year from 18-6-12 Osmocote. This resulted
in a 2 x 3 x 3 factorial experiment which was initiated March 26, 1979 and
terminated after 4 weeks when cuttings had rooted. In this experiment plants
were rated upon removal from the propagation area. Temperatures in the
propagation area were similar to Expt. 1.
Stock plant shade level of 47% only benefited root grade of 'Elaine' in
this experiment, while stock plant fertilizer level had no effect on root
grade (Table 3). However, with both 'Norma' and 'Craigii', there was a trend
toward improved root grade with improved stock plant nutrition. In this
experiment there were no differences in root grade due to propagation
Data generated by these three experiments indicate that best quality
'Craigii', 'Elaine' and 'Norma' plants in Florida are obtained when cuttings
are propagated from stock plants grown under 47% shade. In the experiment where
stock plant fertilization level was considered, fertilization did not show any
real benefit, thus the fertilization rate that produced highest cutting number
should be used (5).
Improvement of plant and/or root quality up to the 4 lb/yd3 rate of
fertilizer in the propagation medium was not consistent and the 6 lb rate was
better in some cases. Inclusion of Osmocote in the medium at the 4 Ib/yd3 rate
is suggested, followed by use of a low level of liquid fertilizer after removal
1. Bjerre, H. 1982. The influence of plant density on plant quality and
time of production for six species of pot plants. Tidsskrift for
2. Christensen, 0. V. 1974. Standardized growing of pot plants II Codiaeum
variegatum Blume 'Geduldig'. Tidsskrift for Planteavl 78:217-229.
3. Christensen, 0. V. 1976. Seasonal variation in the production time of
Codiaeum variegatum. Tidsskrift for Planteavl 80:140-144.
4. Conover, C. A. and R. T. Poole. 1980.
of crotons. Foliage Digest 3(8):10-11.
5. Conover, C. A. and R. T. Poole.
levels on yield of croton stock
96: (In Press).
Factors influencing acclimatization
Influence of shade and fertilizer
Proc. Fla. State Hort. Soc.
Table 1. Influence of stock plant shade level and propagation fertilizer
level on top and root grade of Codiaeum variegatum tip cuttings (Expt. 1).
Top Root Top Root
Treatments grade grade grade gradey
30% 2.6 2.8 2.4 2.6
47% 4.6 4.4 4.9 4.8
2 3.2 3.3 3.2 3.4
4 3.7 3.9 3.3 3.4
6 3.8 3.5 4.4 4.2
Shade .01 .01 .01- .01
Fertilizer NS NS .01 .01
z1 = poor, 3 = average
Y1 = no roots,
to 4" long.
and 5 = excellent quality.
3 = 4 to 6 roots up to 2" long, and 5 = 9 or more roots up,
Table 2. Influence of stock plant shade level and propagation fertilizer
level on root grade of Codiaeum variegatum tip cuttings.
Treatments 'Norma' 'Elaine' 'Craigii'
30% 2.6z 2.2 2.5
47% 4.3 2.9 3.0
2 3.6 2.8 2.6
4 3.3 2.3 2.6
6 3.4 2.6 3.1
Shade .01 .01 .01
Fertilizer NS .05 NS
Z1 = no roots, 3 = 4 to 6 roots
than 4" long.
up to 2" long and 5 = 9 or more roots more
Table 3. Influence of stock plant shade level and stock plant and propagation
fertilizer levels on root grade of Codiaeum variegatum tip cuttings.
Treatments 'Norma' 'Elaine' 'Craigii'
30% 2.0z 1.8 4.3
47% 2.0 2.7 4.2
Osmocote 18-6-12 (Ib N/A/yr)y
900 1.5 2.2 3.5
1500 2.5 2.2 3.9
2100 2.0 2.2 4.5
Osmocote 14-14-14 (Ib/yd3)
2 1.5 2.4 4.1
4 2.0 2.3 4.4
6 2.0 2.0 3.7
Shade NS .05 NS
Stock fertilizer NS NS NS
Propagation fertilizer NS NS NS
z1 = no roots, 3 = 4 to 6 roots up
to 2" long, and 5 = 9 or more roots up to
YEquivalent to 1, 1.8 and 2.5 g/pot/3 mo.