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Copyright 2005, Board of Trustees, University
q C. A. Conover and R. T. Poole FTR 2 1. 199
University of Florida, IFAS
Central Florida Research and Education Center Apopka r
CFREC-Apopka Research Report RH-90-2
Ficus benjamin and Ficus retusa 'Nitida' are among the foliage plants
that respond most positively to acclimatization. Over the years we have
found that production of these plants under specific shade levels
[generally 50 to 70% shade in Florida (approximately 3500 to 5000 ft-c)]
resulted in trees best suited for interiorscape use. Production under less
than 50% shade produces trees with increased potential for leaf drop. In
contrast, those grown under more than 70% shade have reduced food reserves
and therefore decreased ability to replace leaves lost through
mismanagement during shipping and installation (although they often drop
very few leaves after production under 70-80% shade if handled correctly).
Interiorscapers have not fully accepted Ficus grown entirely under
shade because they often desire a heavy, thick trunk and dense foliage
which occurs only under higher light levels. Our research has shown that
thick foliage is a sign of a nonacclimatized tree with the potential to
lose most of the leaves in the center of the canopy when placed indoors.
The beauty of thick trunks lies in the eye of the beholder, but such trunks
cannot be produced on trees grown entirely under shade. However, trunk
size on trees grown under shade is better when they are properly spaced and
grown where some wind movement of the tree occurs (movement causes
increased thickening of trunks).
Producers of the Ficus species under discussion have developed a
system which involves growing trees in full sun until they achieve the
desired height and trunk diameter, then moving them to shade conditions.
Although this system has been acceptable, no comparison has been available
for trees produced entirely under shade conditions versus those grown in
sun and then moved to shade. We conducted several experiments at the
Central Florida Research and Education Center Apopka, FL to compare such
trees under interior environments.
Trees grown under a 63% shade level have large, flat, dark green
leaves widely spaced along branches. Conversely, sun-grown trees have
smaller, lighter green leaves closely spaced along branches. Movement of
sun-grown plants from full sun to 63% shade results in development of trees
with both types of leaves; shade leaves on new growth and sun leaves in the
old canopy center. Depending on the duration of time under shade, a
sun-grown plant can have mostly sun leaves or mostly shade leaves.
Differences in the appearance of plants maintained in full sun and then
switched to 63% shade can vary, but relate to length of time under each
condition (Table 1). Shade-grown plants in this experiment were the
ICenter Director and Professor and Professor, Plant Physiology,
respectively, Central Florida Research and Education Center, 2807 Binion
Road, Apopka, Florida 32703
tallest and had the greatest leaf area and best appearance. Even eight
weeks in 63% shade was insufficient to overcome the partial appearance of
sun-grown foliage on these small trees, although spending over one-half of
the 10 weeks in the shade did improve the appearance of the plants over
those that spent less than one-half of the time in 63% shade.
In another experiment, effects of moving both small (2 gallon) and
larger (4 gallon) Ficus benjamin trees from sun to shade to acclimatize
them was compared toi determine whether size was a factor in
acclimatization. The changes from the previous research were an increase
in duration of the acclimatization period (from 10 to 16 weeks) with 4 week
sun/shade treatment intervals, two sizes of plants, and movement of the
plants into interior rooms after acclimatization treatments were completed.
Overall plant quality was somewhat better for sun-grown plants in this
experiment than in the previous experiment, but plants that spent at least
one-half the 16 weeks in the shade were still better than those that spent
less than one-half the time in the shade (Table 2). Leaf drop after
placement indoors (125 ft-c and 780F) was related to time in full sun.
Both small and large trees that were sun/shade conversions lost more leaves
than those grown entirely under shade. Most leaves were lost from the
center of the canopy and were mainly those produced in full sun. The
percentage of leaves lost from small and larger trees based on total number
of leaves was similar.
Lastly, an experiment was designed to compare the response of both
Ficus benjamin and Ficus retusa 'Nitida' to sun/shade conversion. The
interval for sun/shade treatments was increased to eight weeks to determine
whether greater differences between treatments could be observed. Eight
weeks of full sun followed by sixteen weeks of 63% shade produced plants of
both species that were essentially the same quality as those grown in shade
for the entire 24 weeks. The similarity in quality was also evident in the
interior environment (Table 3), although leaf drop was still greater for
those plants produced for some time under full sun. These data provide
additional information on acclimatization of Ficus benjamin and F. retusa
'Nitida' in that not only is appearance of shade-grown trees better, but
they drop considerably fewer leaves under an interior environment than
converted trees drop. However, the longer the sun-grown trees are held
under shade, the more complete the transformation to an acclimatized shade-
grown tree. At least in small trees, four months of acclimatization is
necessary to gain the appearance of an acclimatized tree, but it is not
sufficient to retard loss of sun leaves. Based on these data we suspect
that, depending on tree size, periods of four months to a year under shade
are necessary to minimize leaf drop.
Table 1. Effect of sun/shade
duration on Ficus benjamin grown in 2
Weeks Weeks Plant Trunk Plant Leaf
full 63% height diameter grades area
sun shade (cm) (cm) (cm )
0 10 119 1.8 4.9 348.5
2 8 102 2.0 4.3 287.3
4 6 107 1.9 4.3 277.8
6 4 90 2.1 3.6 218.8
8 2 88 2.2 3.0 201.8
10 0 89 2.2 2.0 153.0
Z1 = poor; 3 = salable; 5 = excellent
Table 2. Effect of sun/shade duration on plant grade and interior
leaf drop of small (2 gal) and large (4 gal) Ficus benjamin.
Weeks Weeks Plant gradeZ Number of
full 63% leaves droppedY'"
sun shade 2 gal 4 gal 2 gal 4 gal
0 16 4.3 4.3 144 329
4 12 4.3 4.3 273 527
8 8 4.6 4.5 250 531
12 4 3.6 4.1 335 545
16 0 3.4 3.4 286 564
z1 = poor; 3 = salable; 5 = excellent.
YTotal of leaves lost during shipping period (stored in coolers at 65F
for 3 weeks) as well as in the interior environment (1 month).
xFicus in 2 gallon containers averaged 800 leaves/plant and those in 4
gallon containers averaged 2000 leaves/plant before shipping was
Table 3. Effect of sun/shade duration on plant grade and interior
leaf drop of Ficus benjamin and Ficus retusa 'Nitida'.
Plant grades Number of
Weeks Weeks Production Interior leaves droppedY
full 63% benjamin retusa benjamin retusa benjamin retusa
0 24 4.5 3.6 4.3 3.6 76.2 274.8
8 16 4.4 3.4 4.3 3.6 216.8 387.2
16 8 4.1 2.7 3.8 2.4 350.8 888.2
24 0 3.3 2.4 2.9 1.4 556.6 1317.4
21 = poor; 3 = salable; 5 = excellent.
YAverage total leaf drop during shipping (stored in coolers at 650F for 2
weeks) as well as in the interior environment (2 months).