S- ( Effect of Urea Nitrogen and Potassium Ratios on
Golden Pothos Stock Plants and Cuttings r; -. -: ,
A.R. Chase and R.T. Poole'
SEP 3 0 1994
University of Florida, IFAS,
Central Florida Research and Education Center-Apoplty of Florida
CFREC-Apopka Research Report RH-92-6
Fertilizer recommendations change periodically when new research findings oi
application rate, balance of fertilizer elements, or application interval identify potential
improvements in plant production. Many ornamental plant producers changed fertilize
formulations to maximize profits when source of nitrogen (N) was not shown to affect growth
of most foliage plants (3, 4, 5). Additional work demonstrated that containerized Epipremnuw
aureum (golden pothos) stock plants grew well when fertilized with 28 or 56 mg N fror
NH4NO3 (ammonium nitrate) while stock plants receiving 70 mg N produced the best cutting
(6). Previous research has shown that potassium (K) is essential for production of good quality
golden pothos stock plants as well as cuttings (2). Complete fertilizers typically supply N an
K in equal proportions or in a 3:2 ratio. Results of recent fertilizer tests suggest some foliag
plants might benefit from lower N:K ratios (1, 7) while others grow best with the tradition
1:1:1 or 3:1:2 ratio fertilizers (8). The following tests were conducted to determine the effect
of urea as the sole nitrogen source as well as different ratios of N:K on containerized golde
pothos stock plants and the cuttings they produce.
Materials and Methods
Experiment 1. This test began on 18 April 1990, using well rooted golden pothc
cuttings obtained from a commercial nursery. Cuttings were potted, 10 per pot, into 6-inc
standard containers filled with Vergro Container Mix A without superphosphate (Verlite Co.
Tampa, FL 33680). Plants were grown in a greenhouse where maximum light intensity w2
2000 ft-c at leaf level and air temperatures ranged from 65* to 90*F. Plants were watered E
needed to maintain healthy growth, usually twice a week. Immediately after placement in th
greenhouse, containers were top dressed with 39-0-0 urea formaldehyde fertilizer at rates of 1
2, 3, 4 or 5 g/6-inch pot, with ten replicates per treatment.
Potting medium leachate soluble salts levels (umhos/cm) were measured on 5 May an
13 June. Number of leaves and vines, and total vine length were recorded on 13 June. On 1
June, plants were rated for top quality using the following scale: 1 = dead; 2 = poor quality
unsalable; 3 = fair quality, salable; 4 = good quality, salable; and 5 = excellent quality3
salable. Color was also rated on the following scale: 1 = no variegation. solid ereen coloi
2 = poor variegation; 3 = fair variegation; 4 = good variegation; and 5 = excellent
variegation. The number of necrotic leaves per plant was recorded on 18 June. Vines were cut
back to pot rims, fresh vine weights were recorded and vines were utilized for cuttings.
The unrooted cuttings obtained from experiment 1 were planted, 10 per 6-inch standard
pot, in the same medium used for the stock plants. Each container was top dressed with 6 g
19-6-12 Osmocote (Grace/Sierra Co., Milpitas, CA 95035). Five replications per treatment
were established under mist in a greenhouse where light level was 1500 ft-c and temperatures
ranged from 65* to 90F. Experiment 1 ended when cutting quality was rated (using the same
scale employed to determine top quality grades of stock plants) on 19 July 1990.
Experiment 2. The second test, conducted in 1991 during the summer months, was very
similar to experiment 1; therefore, only differences between the two tests are listed below. Six
rates of fertilizer were tested, with containers receiving 1, 2, 3, 4, 5 or 6 g/6-inch pot urea
formaldehyde 39-0-0 on 7 June. Potting medium leachate soluble salts O(mhos/cm) were
measured on 18 June, 23 July and 18 August. Top quality and color (using previously given
scales) were evaluated on 19 July with vine length and fresh weight of vines recorded on 23
July. The experiment was completed with final vine lengths, vine weights, top quality and color
recorded on 21 August. No cuttings were evaluated in experiment 2.
Experiment 3. The final test was a 3 x 4 factorial design with 10 replications per
treatment, and was begun on 11 September 1991. Good quality golden pothos liners were potted
into 6-inch standard containers using the same growing medium as in experiments 1 and 2.
Plants were placed in a greenhouse under 1500 ft-c maximum light intensity where temperatures
ranged from 65" to 90*F and were watered 2 or 3 times per week as needed. Containers were
top dressed with the same urea formaldehyde fertilizer at rates of 0, 2, 4, or 6 g/6-inch pot.
Potassium from 0-0-45 was added at the rate of 0, 3 or 6 g/6-inch pot. All containers received
4 g/6-inch pot of single superphosphate to supply phosphorous requirements.
Soluble salts of potting medium leachate were measured every 4 weeks. Plant quality
was graded (based on the same scale used in experiments 1 and 2) on 22 November. Total vine
length and number of vines per plant were also determined on 22 November. Total vine weight
was recorded on 25 November, the day cuttings were taken from the fresh vines as described
under experiment 1. Cuttings were graded (using the same scale as in experiment 1) 10 January
1992, the day experiment 3 was terminated.
Results and Discussion
June 1990. Cuttings from stock plants receiving urea at either 4 or 5 g/6-inch pot were of
higher quality than those obtained from stock plants fertilized at the 1, 2 or 3 g urea /6-inch pot
rates; although differences were not statistically significant (Table 1).
Experiment 2. Plant growth as indicated by vine weight and length generally increased
as urea rate increased up to the 4 g urea/6-inch pot (Table 2). Top quality was better overall
at the initial rating on 19 July, indicating that available N had reduced significantly by test
completion a month later. Electrical conductivity of leachate from containers of golden pothos
fertilized with 6 g urea/6-inch pot was measured at about 4000 gmhos/cm on 18 June, but had
decreased to 1600 /mhos/cm, on 23 July 1991. Highest quality plants on 21 August were those
receiving 6 g urea/6-inch pot, the highest rate tested in experiment 2 (Table 2).
Experiment 3. The correlation between top quality grade and electrical conductivity
(soluble salts) was significant. Top quality grades increased as electrical conductivity of the
leachate increased to about 4,000 1mhos/cm, regardless of N:K ratios, but decreased gradually
as leachate electrical conductivity increased further to about 6000 tpmhos/cm (Fig. 1). A similar
trend for vine length, weight and number of vines occurred (Fig. 2), although highest ratings
were found at different combinations of N to K. Greatest vine length occurred on stock plants
fertilized with 3 or 6 g of K and 0 g N or 0 and 3 g of K and 2 g of N (Fig. 2). Most vines
were produced with any rate of K and 0 g N, 3 and 6 g of K and 2 g N or 0 or 3 g K and 4 g
N. Finally, total vine weight was highest when plants received 6 g K and 0 g N, 0 and 3 g K
and 2 g N, or 0 g K and 4 g N. Apparently, the effects of K and N are additive for these
growth parameters on golden pothos with overfertilization effects controlled by both K and N
rate. With such differing responses to the same treatments, it becomes difficult to determine
optimal fertility regimes. Quality of cuttings from these stock plants was dramatically affected
by treatment. Plants receiving no K and no urea produced no cuttings due to lack of vine
production. Some cuttings were produced by plants receiving intermediate rates of K and urea.
Although some plants produced salable cuttings, no treatment gave consistently high quality
cuttings in this test. Overfertilization resulted in poor cutting production characterized by both
low yields and low quality cuttings. Fertilization at the 6 g urea/6-inch pot rate caused severe
reductions in cutting production levels regardless of K rate. Best cuttings in, as well as best
overall-stock plants were produced when plants received 2 or 4 g urea/6-inch pot and 3 g K/pot.
Although these results might suggest applying no potassium or no nitrogen, this recommendation
has not been supported by the other research reported here or in the literature.
Best quality plants in experiments 1 and 2 were grown with 4 g urea/6-inch pot. In an
earlier test, comparable quality plants were grown with NH4NO3 at rates of 42 to 56 mg
N/6-inch pot/week soluble fertilizer (6, 9). In experiment 3, N:K ratios did not have a
significant effect on golden pothos stock plant growth, although total of N and K applied greatly
influenced plant growth parameters. This was reflected by the correlation between leachate
electrical conductivity and top quality.
Cutting quality was significantly affected by the fertilizer regime of the stock plant. In
experiment 1, cutting quality increased as rate of urea increased to 5 g/6-inch pot. In
experiment 3, best cuttings were produced when plants received 2 or 4 g urea/6-inch pot and
3 g K/pot. These experiments indicate that nitrogen may be somewhat more important in
affecting both stock plant and cutting quality, although potassium must be available in moderate
amounts to give optimum growth. Finally, urea can serve as a good source of nitrogen for
growth of golden pothos stock and cuttings.
1. Bik, R.A. 1976. Quality in Anthurium andraeanum and Aechmeafasciata grown in peat
substrates as affected by nitrogen and potassium nutrition. Acta Hort. 64:83-91.
2. Chase, A.R. and R.T. Poole. 1991. Effect of potassium and potting medium on growth
of golden pothos. Univ. of Fla., IFAS, CFREC-Apopka Res. Rpt. RH-91-14.
3. Conover, C.A. and R.T. Poole. 1983. Influence of nitrogen source and growth and
tissue content of three foliage plants. Proc. Fla. State Hort. Soc. 95:151-153.
4. Conover, C.A. and R.T. Poole. 1986. Effects of nitrogen source and potting media on
growth of Chamaedorea elegans, Dieffenbachia maculata 'Camille' and Peperomia
obtusifolia. Proc. Fla. State Hort. Soc. 99:282-284.
5. Conover, C.A. and R.T. Poole. 1986. Nitrogen source effects on growth and tissue
content of selected foliage plants. HortScience 21(4):1008-1009.
6. Poole, R.T. and A.R. Chase. 1991. Growth of pothos cuttings affected by nitrogen
fertilization of stock plants. Univ. of Fla., IFAS, CFREC-Apopka Res. Rpt. RH-91-12.
7. Poole, R.T. and C.A. Conover. 1982. Fertilization of birdsnest fern, Asplenium nidus
L. Proc. Trop. Reg. Amer. Soc. Hort. Sci. 25:81-87.
8. Poole, R.T. and C.A. Conover. 1985. Nitrogen, phosphorus and potassium fertilization
of Brassaia actinophylla, Calathea makoyana and Chrysalidocarpus lutescens. J.
Environ. Hort. 3(1):1-3.
9. Reyes, Trinidad, A.R. Chase and R.T. Poole. 1990. Effect of nitrogen level and light
intensity on growth of Epipremnum aureum. Proc. Fla. State Hort. Soc. 103:176-178.
Growth and top quality grade of Epipremnwn aureum stock plants and top quality
grade of harvested cuttings grown with 5 urea fertilizer rates. (Experiment 1 -
18 April 1990 to 19 July 1990).
Vine No. bad Cutting
g 39-0-0/ No. leaves Top grades No. vines length (in) leaves grade
6-inch pot 13 Jun 18 Jun 13 Jun 13 Jun 18 Jun 19 Jul
1 33.7 2.6 2.6 40 3.4 3.1
2 35.2 3.2 4.0 54 4.6 3.2
3 34.3 3.3 2.8 40 2.4 3.4
4 40.2 4.3 3.2 53 1.4 4.1
5 32.6 3.4 2.6 39 2.0 4.0
linear ns ** ns ns ns
quadratic ns ns ns ns ns
zPlants and cuttings were graded using a scale of 1 = dead, 2 = poor quality, unsalable, 3 =
fair quality, salable, 4 = good quality, salable and 5 = excellent quality plants.
Yns, *, **; Results were nonsignificant, significant at P = 0.05 or P = 0.01, respectively.
Growth and top quality grade of Epipremnum aureum stock plants grown with 6
urea fertilizer rates. (Experiment 2 7 June to 21 August 1991).
Total vine Total vine
g 39-0-0/ Top gradez Top grade length (in) weight (g)
6-inch pot 19 Jul 21 Aug 21 Aug 21 Aug
1 3.2 2.2 63 69.6
2 3.6 2.4 66 74.8
3 3.6 2.5 66 78.9
4 4.0 3.2 76 93.5
5 3.2 3.0 69 80.5
6 3.8 3.5 80 91.5
linear ns ** ** **
quadratic ns ns ns ns
Plants were graded using a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair
quality, salable, 4 = good quality, salable and 5 = excellent quality plants.
Yns, **; Results were nonsignificant or significant at P = 0.01, respectively.
UNIVERSITY OF FLORIDA
1111 I IIIIII IIII II
3 1262 05836 2251
Figure 1. Interaction effects of urea-N and K rates on top quality grade of Epipremnum
aureum on 22 November 1991, (Experiment 3).
Top quality grade
Urea rate (g/6
i 0 g K/6 Inch pot EM 3 g K/6 Inch pot Z 6 g K/6 Inch pot
Top quality grade; 1-dead, 2-poor,
3- fair, 4-good, and 5-excellent
Figure 2. Interaction effects of urea N and K rate on total vine length (inches) of
Epipremnum aureum on 22 November 1991, (Experiment 3).
Vine length (inches)
0 2 4 6
Urea rate (g/6 in pot)
M 0 g K/6 Inch pot E 3 g K/6 Inch pot E 6 g K/6 Inch pot