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ENH1286
Cultural Guidelines for Commercial Production of
Boston Fern (Nephrolepsis exaltata ‘Bostoniensis’)1
Bill Schall, Heqiang Huo, and Jianjun Chen2
1. This document is ENH1286, one of a series of the Environmental Horticulture Department, UF/IFAS Extension. Original publication date January 2018.
Visit the EDIS website at http://edis.ifas.u.edu.
2. Bill Schall, Extension agent IV, UF/IFAS Extension Palm Beach County, West Palm Beach, FL 33415; Heqiang Huo, assistant professor, Mid-Florida
Research and Education Center, UF/IFAS Extension, Apopka, FL 32703; and Jianjun Chen, professor, Mid-Florida Research and Education Center, UF/
IFAS Extension, Apopka, FL 32703.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to
individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national
origin, political opinions or aliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension oce.
U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County
Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.
Introduction
Nephrolepis exaltata (L.) Schott, commonly known as sword
fern, is native to North, Central, and South America, the
West Indies, and Africa (Grith 2006). e fronds are
rigid and erect, 50–150 cm long, and 7–15 cm wide. e
pinnae are close. e fronds form a rosette and the plant
has a compact, upright form (Hvoslef-Eide 1991). e
wild sword fern was cultivated as a house plant. In 1895, a
mutant exhibiting gracefully arching fronds was discovered
in Boston (Blaydes 1940). Due to its improved ornamental
value and more tolerance to indoor environmental condi-
tions, the mutant was named as N. exaltata ‘Bostoniensis’
and quickly gained its popularity as Boston fern. Since then,
many cultivars have been selected from ‘Bostoniensis’, and
Boston fern cultivars have almost entirely replaced the wild
species and become one of the most important foliage crops
in the ornamental plant industry (Henny and Chen 2003).
Boston fern varieties take many forms and are prized for
their curly, wavy, arching, double-pinnate, and overlap-
ping fronds. Some larger Boston fern cultivars are grown
outdoors in Florida landscapes as a ground cover in shady
areas where winter permits. Smaller, more ornate varieties
are grown in containers as potted plants or hanging baskets
for interiorscaping. is article describes common Boston
fern cultivars in the foliage industry, provides guidelines
for their culture and interior use, and lists physiological
problems that may be encountered during production and
interiorscape use (Figure 1).
Cultivars
Major Boston fern cultivars are listed in Table 1. e
selection of cultivars should be based on whether the crop
is intended for landscape or interiorscape usage. e nal
plant size and growth habit will determine how the crop
Figure 1. Boston fern production and use as an indoor foliage plant;
shaded greenhouse production of Boston fern as potted plants on
ground and as hanging baskets.
Credits: Jianjun Chen, UF/IFAS
2
Cultural Guidelines for Commercial Production of Boston Fern (Nephrolepsis exaltata ‘Bostoniensis’)
is handled throughout production (Kessler 2001). Larger
varieties are well-suited to landscape use or application
for a porch hanging basket or parlor fern. Smaller, ne-
textured cultivars are well suited as attractive foliage plants,
but may develop growth problems under low light and
humid conditions due to their dense foliage.
Growers should be aware that other sword ferns, such as
tuberous sword fern (Nephrolepis cordifolia) and Asian
sword fern (Nephrolepis multiora), are non-native to
Florida and are listed as Florida’s most invasive species in
category I and II, respectively (Landeland 2014).
Cultural Guidelines
Propagation
Historically, Boston ferns were propagated by dividing
older plants grown in stock beds outdoors (Henley 1991).
Propagation using greenhouse-grown stock maintained on
raised benches or in hanging baskets provides maximum
environmental control and better sanitation. Growers start
either with plantlets pulled or divided from stock plants,
or they use liners started in plug trays. Today, a majority of
Boston fern cultivars are propagated through tissue culture
and sold in 72-, 98-, or 162-cell trays.
Containers
Tissue culture liners are usually potted in small pots rst.
For example, plugs from 72-cell trays should be trans-
planted into 4-inch pots and grown for 6–8 weeks to reach
a good size, and then transplanted to a 10-inch or larger
pot. is is generally good technique for many plants, but
more critical for some for Boston ferns. Final selection of
containers depends on plant size; large containers are used
for growing large-sized cultivars and smaller containers are
used for small-sized cultivars. Plants intended for landscape
use are generally potted directly into 3-gallon size utility
pots for growing on in a shadehouse production area.
Boston ferns for indoor use are commonly greenhouse-
grown in 8-, 10-, or 12-inch plastic hanging baskets. e
hanger assembly for the basket should be quick and easy to
attach, and the hanger assemblies should be strong enough
to support the weight of the mature crop without breaking.
Plastic hanging baskets are oered for sale with either an
internal water reservoir or an external, detachable saucer.
Some growers prefer to remove external saucers during
production to reduce the occurrence of waterlogged soil.
Saucers are then re-attached prior to packing and shipping
when the crop is sold.
Potting Medium
e potting media for growing Boston ferns should be
well-aerated and well-drained. It should have a high water-
holding capacity so that it will not dry out too rapidly.
A medium composed of 50% peat, 25% perlite, and 25%
vermiculite based on volume with a water-holding capacity
by volume of 73% was used for producing quality ‘Fluy
Rue’ (Conover and Poole 1992). Many commercially
prepared mixes sold by suppliers have characteristics neces-
sary to produce a good crop. Growers should avoid using
native soils in the potting media to prevent contamination
from soilborne diseases, insects, and nematodes. e pH
should be 5.0 to 5.5.
Irrigation
Boston ferns should be watered by hand using a hose
with a water breaker nozzle to settle the roots aer initial
planting. Plants grow most rapidly when medium is kept
evenly moist but not saturated for a long period. During
winter months, low light and cool temperature conditions
can cause problems for young, recently potted plants. e
grower should adjust watering requirements.
Large pots intended for landscape production and hang-
ing baskets can be watered eciently using micro-tube
irrigation systems. Production areas designed for Boston
fern hanging baskets frequently utilize automated timing
systems and micro-tube irrigation. Small pots can be wa-
tered using sub-irrigation or by hand using a water breaker.
Water application early in the morning is favorable to allow
the foliage to dry during the day and prevent disease issues
in ne-leaf, specialty varieties.
If plants are allowed to get too dry, the foliage of Boston
fern develops a gray color and growth slows.
Fertilization
Newly potted liners should not be fertilized until the
roots are well established. Liquid fertilization is the most
common method of application in the production of small
Boston fern varieties grown in small containers. Apply
a low-ammonium formula at a rate of 150 to 175 ppm
nitrogen on a constant liquid feed basis using a fertilizer
injector system. During warmer, brighter periods when
growth is active, a 20-10-20 fertilizer may be used at 175
to 200 ppm nitrogen. Where constant liquid feed is not
available, 250–300 ppm nitrogen once per week works well.
Many growers of the large landscape varieties and hanging
baskets incorporate slow release fertilizer into the soil
mix at a rate recommended by the product manufacturer.
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Cultural Guidelines for Commercial Production of Boston Fern (Nephrolepsis exaltata ‘Bostoniensis’)
However, lack of uniform mixing with the medium can be
a problem. Growers may top dress large pots and hanging
baskets with a slow release fertilizer such as Osmocote® or
Nutricote® at the manufacturer’s rate recommended for a
particular pot size.
Growers are recommended to monitor media-soluble
salts or electronic conductivity (EC) and pH every 2 or 3
weeks using the pour-through method of soil testing. If the
soluble salts reading is 1 dS/m, the plants will show nutrient
deciency if no additional fertilizer is provided. If the
soluble salts reading is 2 dS/m, nutrient levels are adequate;
and if the reading is 3 dS/m or above, reduce either the
rate or the frequency of fertilizer application. In some
cases, leaching the media with water is necessary to reduce
soluble salts buildup. Table 2 provides a guide for determin-
ing if Boston fern cultivars are appropriately fertilized based
on leaf analysis.
Light
Boston ferns have a wide tolerance to changing light levels,
but grow well when receiving 1,500 to 3,000 -c, with best
quality usually produced near 2,000 -c (Henley 1991).
During the summer, high heat and high light intensity may
need to be controlled. Light intensity can be reduced in the
greenhouse by installing a 30% to 60% shade fabric. Too
much light causes fronds to become light green in color.
Light intensity that is too low results in elongated, weak
fronds that are dark green in color but few in number.
Temperature
Suggested air temperature for producing Boston fern ranges
from 65°F to 86°F. e crop may tolerate slightly lower and
higher temperatures depending on cultivars. Controlled
environmental studies showed that maximum leaf area per
frond, total frond area, and total dry weight were achieved
with an average daily temperature of 75°F (Dawson et al.
1991). Growers producing hanging basket crops should be
aware that greenhouse temperatures may stratify vertically.
Temperatures where hanging baskets are located may be as
much as 10 degrees warmer than at bench level.
Shipping and Interior Care
When smaller, more delicate frond varieties grown in
small pots are pulled from shaded greenhouses for packing
orders, care must be taken to avoid placing the pots into full
sun on carts and loading docks. Sunburning can occur.
Finished plants should be groomed and packed by inserting
individual plants into sleeves and placing the sleeved plants
into appropriate boxes or cartons or onto structured racks
for shipping. Sleeves are necessary because the fronds may
break or tear.
Ferns should be transported in temperature-controlled
trucks between 60°F to 65°F to avoid damage by both
hot and cold temperature extremes especially during
long distance shipping. Boston fern are fairly tolerant to
ethylene.
Once arriving at their nal destination aer shipping,
plants should be placed in interior light levels between 50 to
200 foot candles. Occasional grooming is needed to remove
senesced fronds. Media should be kept slightly moist in
interior conditions. Temperatures of 68°F to 75°F are most
appropriate.
Larger Boston ferns for landscape installations should be
sleeved and care should be taken not to crush plants when
stacking into a truck. Plants should be installed as quickly
as possible aer arriving at the work site. Boston ferns will
perform best in landscapes with partial to deep shade. Soil
should be moist but well-drained. Plant on 12- to 24-inch
centers for quick establishment. Established beds can
survive periodic bouts of dry weather. Light fertilization
is recommended during the growing season followed by
irrigation to wash granules o the fronds. ick established
clumps can be managed by severe pruning. New fronds
quickly sprout from the roots.
Physiological Problems
Common physiological problems in Boston fern produc-
tion and interiorscape usage are listed in Table 3. Most
problems are related to poor management of water,
nutrients, and improper use of chemicals.
References
Blaydes, G.W. 1940. “Evolution of Boston fern varieties.”
e American Biology Teacher. 2:145–146.
Chen, J., D.B. McConnell, D.J. Norman, and R.J. Henny.
2005. “e foliage plant industry.” Horticultural Reviews.
31:45–110.
Conover, C.A., and R.T. Poole. 1992. “Eect of fertilizer and
irrigation on leachate levels of NH4-N, NO3-N, and P in
container production of Nephrolepis exalta ‘Fluy Rue’.”
Journal of Environmental Horticulture. 10:238–241.
Conover, C.A., L.N. Satterthwaite, and K.G. Steinkamp.
1994. “Eects of controlled-release fertilizers containing a
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Cultural Guidelines for Commercial Production of Boston Fern (Nephrolepsis exaltata ‘Bostoniensis’)
nitrication inhibitor on leachate characteristics.” Proceed-
ings of Florida State Horticultural Society. 107:188–191.
Dawson, I.A., R.W. King, and R. van der Staay. 1991.
“Optimizing conditions for growth of Nephrolepis ferns.”
Scientia Horticulturae. 45:303–314.
Grith, L.P. 2006. Tropical Foliage Plants: A Grower’s Guide.
Batavia, IL: Ball Publishing.
Henley, R.W., L.S. Osborne, and A.R. Chase. 1991. “Produc-
tion Guide: Boston Fern.” CFREC-Apopka Research Note
RH-91-8.
Henny, R.J. and J. Chen. 2003. “Cultivar development
of ornamental foliage plants.” Plant Breeding Reviews.
23:245–290.
Hvoslef-Eide, A.K. 1991. “e eect of temperature, day
length and irradiance on the growth of mother plants of
Nephrolepis exaltata (L) Schott and on the subsequent
growth in vitro runner tip explants.” Scientia Horticulturae.
47: 137–147.
Kessler, J. Raymond. 2004. “Greenhouse Production of
Boston Ferns.” Extension sheet ANR-1095, Alabama
Cooperative Extension System, Auburn, AL 36849.
Langeland, K.A. 2014. Natural area weeds: Distinguishing
native and non-native ‘Boston ferns” and ‘Sword ferns
(Nephrolepis spp.) AG120. Gainesville: University of Florida
Institute of Food and Agricultural Sciences. http://edis.ifas.
u.edu/ag120
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Cultural Guidelines for Commercial Production of Boston Fern (Nephrolepsis exaltata ‘Bostoniensis’)
Table 1. Key characteristics of Boston fern cultivars currently in the market as of 2017.
Cultivar Characteristics
Ariane A mutant selected from ‘Fluy Rues’. It has shiny, dark-green fronds and a slightly more upright growth habit
than its parent, and is suitable for a wide range of container or basket sizes.
Boston Blue Bell Has a compact growth habit and can be grown and sold in smaller pot and basket sizes. It is one of the most
popular Boston fern cultivars in Europe.
Bostoniensis This is the earliest selection of N. exaltata. It is a large fern that is more pendulous and graceful than the native
sword fern.
Bostoniensis Compacta This is an intermediate size fern. Its fronds are shorter, more compressed, and less pendulous than `Bostoniensis’.
Corditas Has sturdy, erect fronds that are close together and are densely covered with ne, dark-green leaets. It is a fast-
growing cultivar with a maximum frond length of 12 inches (30 cm). This dwarf fern is ideal for smaller pot sizes
and dish garden arrangements.
Emina Displays dark green fronds maturing into crinkly/curly patterns. The fronds of this strong, compact cultivar
stand erect, and its slow growth habit makes it excellent for smaller pot sizes. This fern is suitable for 3 to 6 inch
(7–15 cm) containers and can commercially be grown with very close spacing.
Nevada A mutant selected from ‘Boston Blue Bell’, ‘Nevada’ has much darker leaves than ‘Boston Blue Bell’. Its leaves and
the leaets are also wider and longer than the leaets of ‘Boston Blue Bell’.
Pompom Has dark green fronds that form a very tight, full, rounded plant. Often used for dish gardens or in hanging
baskets.
Tiger Fronds are long and pendulous, with a dark green coloring and gold variegation. Does well in shade with
regular water when grown in a basket.
Fluy Rues A compact cultivar with sturdy, erect fronds that reach a maximum length of 12 inches (30 cm). The fronds are
dark green with an almost leathery texture. ´Fluy Rues´ is commonly grown in small pots or small baskets.
Table 2. Nutrient concentrations in leaves that are generally considered low, medium, or high for Boston fern (Nephrolepis exaltata
‘Bostoniensis’) growth (Conover et al. 1994).
Nutrient Low Medium High
Nitrogen (%) < 2.0 2.0–3.0 > 3.0
Phosphorus (%) < 0.4 0.4–0.8 > 0.8
Potassium (%) < 2.5 2.5–4.0 > 4.0
Calcium (%) < 0.5 0.5–2.0 > 2.0
Magnesium (%) < 0.3 0.3–1.0 > 1.0
Sulfur (%) < 0.2 0.2–0.6 > 0.6
Iron (ppm) < 150 150–100 > 100
Manganese (ppm) < 50 50–400 > 400
Zinc (ppm) < 30 30–150 > 150
Copper (ppm) < 5 5–10 > 10
Boron (ppm) < 30 30–75 > 75
Table 3. Causes and treatments of various physiological problems (Henley et al. 1991).
Symptom Probable Cause Treatment
Graying—fern has gray cast with reduced growth
rate and few runners
Plants have not received sucient water,
and growth rate and runner production
decrease if potting medium is not
consistently moist.
Increase irrigation to supply sucient water
and keep media moist but not wet.
Weak fronds—plants have a reduced number
of fronds and fronds that are long, weak, and
pendulous.
Low light levels. Increase light levels to reduce frond length
and increase strength.
Fronds become pale in color Light levels are too high. Decrease light levels to 2000 foot candles.
Leaf tip and runners burn—frond tips and leaets
and runner tips turn brown and die.
High media soluble salts or phytotoxicity
caused by spraying chemicals
Leaching of media with good quality
irrigation water and appropriate application
of pesticides, fungicides, or bactericides.
