e of Transplanting Depth on Norfolk Island Pine Growth and Quality
'':" Y C.n n Cr'
1 1 j U I J k I t- N i i ,
R.T. Poole and C.A. Conover1'
University of Florida, IFAS SEP 3 0 1994
Central Florida Research and Education Center Apopka
CFREC-A Research Report, RH-92-3 University of Florida
Popular journal articles discussing transplanting of foliage and woody ornamentals
advise growers to place root balls at the same depth in the growing medium as the roots had
been before transplanting (3, 5). This recommendation, however, is based on old
information (4), and no recent research is available on the effects of placing root balls of
woody ornamentals at depths different than where roots were prior to repotting. The
following experiment was conducted to examine the effects of transplanting Araucaria
heterophylla (Salisb.) Franco (Norfolk Island pine) with root balls placed in medium deeper
than roots were when growing in their original containers.
Materials and Methods
This experiment was initiated on 12 February 1991 when good quality Norfolk Island
pine plants, 15 to 20 cm (6 to 8 in) tall, in 10 cm (4 in) pots were obtained from local
nurserymen. Plants were transplanted into 20 cm (8 in) containers using a medium
composed of Florida sedge peat, pine bark and builders' sand, in a 6:3:1 combination by
volume, amended with 3 kg/m3 (7 lbs/yd3) dolomite and 0.45 kg/m3 (1 lb/yd3) Micromax (a
micronutrient blend manufactured by Grace/Sierra Co., Milpitas, CA 95305). Norfolk Island
pines were placed in pots so that the top of the root mass was 1, 3, 5, 7 or 9 cm (0.4, 1.2,
2.0, 2.7 or 3.5 in) below medium surface, and 10 replicates were planted for each of the 5
planting depth treatments tested. Plants were grown in a shadehouse where maximum light
intensity at plant level was 3500 ft-c and minimum and maximum air temperatures were
16C (60F) and 35C (95*F), respectively. Plants were watered 2 to 3 times per week, as
needed to maintain medium moisture levels needed for healthy growth. Osmocote 19-6-12
(Grace/Sierra Co., Milpitas, CA 95305) was surface applied to medium, 5 g/20 cm (8 in)
pot, on 12 February, 4 June and 18 October 1991.
Plant height (cm) was measured 1 March, 17 June and 26 November 1991. Plants
were graded using a scale of 1 = poor quality, unsalable, 3 = fair quality, salable and 5 =
excellent quality plants on 14 November 1991. Research was concluded on 26 November
1991, after final height measurements were recorded.
'Professor of Plant Physiology and Professor of Environmental Horticulture and Center
Results and Discussion
Tallest plants, after about nine months of growth, were those with tops of root balls
laced 5 or 7 cm (2.0 or 2.7 in) below growing medium surface (Table 1). Plants with root
all tops transplanted 5 or 7 cm (2.0 or 2.7 in) below medium surface also received higher
[ant grades compared to other plants grown in this test (Table 2). Pines with root systems
ansplanted 1 cm (0.4 in) and 9 cm (3.5 in) below medium surface were not as sturdy as
plants with root systems transplanted at the other levels tested.
When transplanting root balls of Norfolk Island pines from 10 to 20 cm (4 to 8 in)
ats in this experiment, plants grew better when root balls were placed 5 or 7 cm (2 to 2.7
i) deeper than they were originally located in the 10 cm (4 in) pots.
Crockett, J.U. 1971. Evergreens. Time-Life Books, New York, NY.
Fullaway, E.T., T.K. Tagawa, E.Trujillo, C.J. Davis, A.A. LaPlant and E.Pung.
1972. Norfolk Island pine culture. Hawaii Univ. ext. circ 453, 16 pp.
Logsdon, B.B. 1973. Growing the Norfolk Island pine. U.S. Forest Service Tree
Planters' Notes. 24(2):33-36.
Nicholls, R. 1975. Plants and pots pp 19-26. In: The Plant Doctor. Running Press,
38 South Nineteenth Street, Philadelphia, Pennsylvania 19103.
Pirone, P.P. 1978. Tree Maintenance, 5t Ed., p 44. Oxford Univ. Press, New
Rice, L.W. and R.P. Rice, Jr. 1986. Indoor plant maintenance pp 315-339. In:
Practical Horticulture. Prentice-Hall, Englewood Cliffs, NJ 07632.
A'UI alIJ 1..' (L ll*ilU L l.U Al6 III tU|ULJ V J.JIV 11i A J.T.all.A Uil.. AVW
(cm) 1 Mar 17 Jun 26 Nov Height change
1 23 33 52 29
3 25 36 53 29
5 24 36 58 34
7 24 36 59 35
9 19 31 52 33
linear 0.005 0.565 0.412 0.042
quadratic 0.002 0.017 0.063 0.351
'Final plant height measured on 26 November Initial plant height measured on 1 March =
Table 2. Plant grade of Araucaria heterophylla transplanted at various depths on 12
February 1991. Plants graded on 14 November 1991.
Transplanting depth (cm) Plant grade
,~,~m~ t,,,r,,t\ll, c,