Group Title: CFREC-Apopka research report - Central Florida Research and Education Center-Apopka ; RH-90-1
Title: Light and fertilizer recommendations for production of acclimatized potted foliage plants
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Permanent Link: http://ufdc.ufl.edu/UF00065873/00001
 Material Information
Title: Light and fertilizer recommendations for production of acclimatized potted foliage plants
Series Title: CFREC-Apopka research report
Physical Description: 13 p. : ; 28 cm.
Language: English
Creator: Conover, Charles Albert, 1934-
Poole, R. T ( Richard Turk )
Central Florida Research and Education Center--Apopka
Publisher: University of Florida, IFAS, Central Florida Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1990
 Subjects
Subject: Foliage plants -- Effect of light on -- Florida   ( lcsh )
Foliage plants -- Fertilizers -- Florida   ( lcsh )
Acclimatization (Plants) -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: C.A. Conover and R.T. Poole.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065873
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70551502

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ao



i OlL LIGHT AND FERTILIZER RECOMMENDATIONS FOR
PRODUCTION OF ACCLIMATIZED POTTED FOLIAGE PLANTS

C.A. Conover and R.T. Poole ,o 'r(
University of Florida, IFAS
Central Florida Research and Education Center Apopka
CFREC-A Research Report RH-90-1

Acclimatized foliage plants have become the standard of the industry
and have increased consumer acceptance of interior plants with their
increased tolerance of interior environments. Although many factors
influence acclimatization, the most important during production of foliage
plants are light intensity and fertilization level.

LIGHT

Plants can be divided into three categories according to their
physiological responses to light. The first group includes extreme shade
plants, those that require moderate to heavy shade to produce attractive
plants and cannot be acclimatized to high light. Examples of these plants
include Aglaonema, Maranta and Spathiphyllum. The second category includes
plants that must have high light to grow and cannot be acclimatized to low
light. For the most part, none of these plants are used in the foliage
industry, but would include plants such as pine trees or flowering annuals
that require full sun to bloom profusely. The last category includes
plants termed sun-shade, which means they can adapt or be acclimatized to a
wide range of
light intensities. Examples of these plants include Brassaia,
Ficus and Dracaena; it is within this group we find the greatest
application of the light acclimatization process.

Research has shown that foliage plants can be light-acclimatized in
two ways: 1) plants can be grown under a specific shade level for their
entire production period, or 2) they can be grown under high light or, in
some cases, full sun and then converted to low light at some period during
production. Extreme shade plants must always be grown under shade, while
sun-shade plants can be grown with either system.

PRODUCTION UNDER SHADE

Foliage plants grown under suggested shade levels from propagation to
finishing have the highest degree of acclimatization. This system is the
normal production system for most foliage plants and yields plants with low
light compensation points, good color and an open canopy that allows the
most efficient use of available light indoors. Excellent quality
acclimatized foliage plants can be produced by using the light intensity

1Center Director and Professor and Professor, Plant Physiology,
respectively, Central Florida Research and Education Center, 2807 Binion
Road, Apopka, Florida 32703









recommendations in Table 1. These plants will have excellent interior
longevity and provide long consumer satisfaction when produced with other
good cultural practices.

PRODUCTION UNDER SUN AND CONVERSION UNDER SHADE

Some foliage plants grow rapidly in full sun and produce a form that
is considered more aesthetically acceptable to some producers, buyers and
interiorscapers. A common example is Ficus cultivars which produce heavier
caliper trunks and more compact crowns in full sun. Many consumers also
prefer the shape of Araucaria and Brassaia grown in full sun. Other genera
used for interiors that are sometimes grown in full sun include
Chamaedorea, Chrysalidocarpus, Dracaena, Sansevieria and Yucca. Time
necessary to achieve sun-shade conversion depends on cultivar, plant size
and method of production. Small plants grown in containers are able to
convert much faster than large plants, with large field-grown plants taking
the longest time to convert. However, we suggest shade growing for all
plants in 10-inch (3 gallon) containers and smaller. Larger specialty
plants such as Brassaia and Ficus can be converted and will yield good
quality plants. Suggested shade levels for proper conversion are
equivalent to those recommended for production (Table 1). Most plants
require 8 weeks to 12 months or more to convert, depending on size.

Much has been written about the relative value and likelihood of
indoor survival of sun-shade conversions, but the actual effects will
probably never be known because of the widely differing conditions under
which these plants are utilized. Some facts are known, however, and relate
mainly to Ficus benjamin: 1) lowest light compensation points will only be
achieved when all sun-grown leaves have been replaced by shade leaves;
2) because of the larger trunk surface area and root volume in relation to
leaf surface area, sun-grown trees will have higher respiration rates than
shade-grown trees and never achieve the same level of acclimatization; and
3) sun-shade conversions appear acceptable for most interior situations
except those with marginal light conditions (less than 125 ft-c).

NUTRITION

Fertilization of foliage plants has a direct effect on acclimatization
which may be related to respiration rate and/or high soluble salts. During
production high levels of nitrogen, and to some extent potassium, have been
shown to decrease ability of foliage plants to adjust to interior
environments.

An understanding of the potting medium pH is necessary before
fertilizer programs can be developed since it controls release of
nutrients. A low pH will reduce conversion of ammonium to nitrate
nitrogen, while high pH levels reduce availability of most microelements.
Most foliage plants grow best when the pH is between 5.0 and 6.5 although
some plants, such as Maranta and Calathea, prefer a range of 5.0 to 6.0.









Low pH levels can be raised in potting media by addition of liming
material, such as dolomite or calcium carbonate, while high pH levels can
be lowered by addition of sulfur. The amount of liming material or sulfur
needed to obtain a desired pH depends on the type of organic material
present in the medium and the original pH; small amounts of lime or sulfur
will change pH of sandy potting media while larger amounts are needed to
change pH of peat moss. Table 2 provides a guide for adjusting pH levels
of potting media during preparation.

The pH level should be adjusted prior to planting crops since changing
the pH is difficult once plants are growing in the medium. The best
material to raise pH after planting is calcium hydroxide (hydrated lime).
However it can damage plants unless applied in solution of one pound/100
gal or less to 100 ft2 of surface area (pots or benches). Plants can be
treated again in 4 weeks if pH has not reached desired levels. Calcium
carbonate applied to the potting medium surface and watered in will also
raise pH, but it usually takes longer before its effect is noticeable.
When pH levels are too high, sulfur can be applied at the rate of 1 lb/100
ft to lower pH. Do not apply sulfur more often than every 4 weeks until
the desired level is reached because plant damage may result from rapid pH
changes. Irrigation after application of liming materials or sulfur
application will remove residues from foliage and speed pH changes.

In addition to raising pH, dolomite also provides the essential
elements calcium and magnesium, whereas the addition of sulfur to lower the
pH will supply that essential element. If these elements have not been
added to the media while adjusting the pH, be certain that they are added
by some other means to ensure proper plant growth. Sulfur may be present
in the water supply but ascertain that the proper level will be supplied.

SOLUBLE SALTS

Soluble salts should be determined prior to medium utilization. For
media with high salts, addition of unnecessary fertilizer ions can be
avoided by use of special fertilizer programs and plant damage can be
reduced by more frequent applications of smaller amounts of fertilizer.

MICROELEMENTS

In most potting media for foliage plants, microelements are needed.
If good mixing equipment is available, microelements should be thoroughly
incorporated into the medium at time of mixing. Many products are
available for this purpose; Micromax (Sierra Chemical Co., Milpitas, CA)
and Perk (Estech General Chemical Corp., Chicago, IL), both of which also
contain sulfur, have given excellent results in experimental plots when
added at the rate of 1 to 1-1/2 lbs/yd3. If micronutrients cannot be mixed
into the potting medium, they may be added separately or incorporated into
the fertilizer program, either as a periodic application or along with
every fertilizer application.









Average amounts of 6 microelements that are needed on an annual or
monthly basis to grow good quality foliage plants are given in Table 3. If
a micronutrient mix is incorporated into the potting medium, annual rates
should not be started until at least 6 months after potting; monthly rates
may be started one month after planting.

SUPERPHOSPHATE

Incorporation of superphosphate into potting media for foliage crops
has been a common practice. Research on foliage plants, however, has shown
that incorporation of superphosphate is unnecessary for quality foliage
plant production, if other sources of phosphorus are used, and can result
in serious phytotoxicity on some foliage genera from excessive fluoride
levels. Superphosphate contains 1 to 2% fluoride as a contaminant and this
causes foliar damage on Calathea, Chlorophytum, Cordyline, Dracaena,
Maranta, and Yucca. Since no unique benefit has been observed from
superphosphate additions to potting media used for production of foliage
plants, use of other sources of phosphorus is suggested.

FERTILIZER RATIOS

Relative levels of nitrogen, phosphorus and potassium in a fertilizer
analysis are referred to as the N-P2Os-KO2 ratio. Research in this area
has shown that foliage plants grow very well with a 1:1:1 ratio, such as in
an 8-8-8 or 20-20-20 fertilizer analysis, but will do just as well with a
3:1:2 ratio, such as a 9-3-6 or 18-6-12 analysis. The benefits of using
the 3:1:2 ratio are reduced fertilizer costs per unit of nitrogen and lower
total soluble salts levels which improve a plant's ability to acclimatize
to interior environments. For these reasons, a 3:1:2 ratio fertilizer is
suggested for foliage plant production where soilless potting media are
utilized. When potting media are used that include clay-containing soils,
it is suggested that a 1:1:1 ratio be used to prevent reduced availability
of phosphorus and potassium.

FERTILIZER LEVELS

Selection of the proper amount of fertilizer to apply to a specific
foliage crop varies with the growing environment. Some major factors
influencing fertilizer requirements include light intensity, temperature,
rainfall or irrigation level, and cation exchange capacity (ability of the
potting medium to retain nutrients).

Light. Growth of plants can be optimized at light intensities that
provide highly acclimatized plants by selection of an appropriate
fertilizer level. See Table 1 for information on suggested fertilizer
levels for a wide variety of foliage plants when grown under recommended
light intensities. If plants are grown under higher light intensities (not
recommended for production of acclimatized plants), even full sun for
plants like schefflera or areca palms, the suggested fertilizer levels will
have to be increased by 50% or more. If lower light intensities are
present, suggested fertilizer levels can be reduced by as much as 25%.








Temperature. Most foliage plants grow slowly, if at all, when soil
temperatures drop below 600F and night air temperatures are 650F or below;
thus, maintenance of standard fertilizer levels during this time is
unnecessary and can often be reduced by up to 50%. Slow-release
fertilizers are only partially available to plants during periods when
potting media are cold, but become available as media warm; therefore,
rates can be adjusted with such fertilizers by lengthening the time between
application periods. During high temperature periods (850F to 950F days
and 750F to 850F nights), foliage plants grow rapidly and can utilize
slightly more fertilizer than listed rates. A general rule that will
account for cool and warm season foliage production is to reduce suggested
fertilizer levels by 25% during December February and raise them by 25%
from June September.

Rainfall or irrigation level. Amount of water applied to the pot,
either naturally or mechanically, affects the amount of fertilizer leached
from potting media. In greenhouse irrigation, rates should be selected
that wet the potting medium but provide minimal or no leaching. When
proper irrigation is combined with correct fertilization levels, plant
quality will be maintained and contamination of ground water prevented.
Leaching of the potting medium is more difficult to control for plants
grown in the open or under shade, but it is important to control or limit
leaching to lessen fertilizer run-off for environmental as well as economic
reasons. Irrigation scheduling must factor in rainfall since addition of
an irrigation sequence on already saturated media will leach fertilizer and
possibly contribute to ground water pollution.

Cation exchange capacity. Cation exchange capacity determines
nutrient retention ability of a medium and is a necessary factor in
calculating fertilizer levels. Fertilizer levels in Table 1 are based on
utilization of potting media composed primarily of organic components with
high cation exchange capacity. Examples of such potting media include (1)
75% peat moss 25% sand, (2) 50% peat moss 25% pine bark 25% cypress
shavings, and (3) 80% peat moss 20% perlite, polystyrene foam or similar
materials. Potting media composed of greater amounts of sand, perlite,
polystyrene foam or pine bark may require slightly higher fertilizer levels
because of decreased nutrient retention ability.

FERTILIZER SOURCES

Selection of a fertilizer includes not only the form of the fertilizer
such as liquid, granular or slow-release, but also the source of the
nutrients themselves.

Nutrient form. Method of fertilizer application and economics
influence the selection of a fertilizer form. However, another factor that
has become very important is the potential for pollution of ground water by
specific fertilizer sources and forms. The Department of Environmental
Regulation (DER) is looking closely at nitrate contamination of ground
water in relation to ornamental producers in Florida. Monitoring of
nursery wells has indicated that the federal maximum of 10 ppm nitrate
nitrogen (NO3-N) in ground water has been exceeded in one Florida nursery
and in several greenhouse operations in the northeastern U.S. For this
reason, we are suggesting use of fertilizer forms and application methods








that minimize potential for contamination. The primary fertilizer forms
are liquid and slow-release. The way these fertilizer forms are utilized
contributes to the potential for leachate to reach the ground water;
overhead sprinkler fertilization (fertigation) has the greatest potential
and slow-release or liquid fertilizers placed directly into the container
offer the least potential for ground water contamination. Factors that
influence selection of liquid or slow-release fertilizers is covered in
"Effective and Economical Fertilizer Considerations", Agricultural Research
Center-Apopka Research Report RH-80-3.

Nutrient sources. Although nitrogen, for example, is presently
available in fertilizer from three primary sources nitrate (NO ),
ammonium (NH ), and urea [CO(NH )2] foliage producers have not always
considered te nutrient source when selecting a fertilizer. Formerly most
fertilizers contained 20% to 50% nitrate nitrogen and the remainder came
from ammonium or urea nitrogen forms. In recent years fertilizer
formulators have substituted urea for much of the nitrate nitrogen because
of its lower cost. Recent research on foliage plants has shown that
ammonium and urea nitrogen were as good as or better than the nitrate form
and lower in cost. Although we found no problem in utilizing 100% urea or
ammonium nitrogen sources and combinations, these have not been tested on
all genera and therefore we still suggest using a small amount of nitrate
nitrogen (10-15 percent). On flowering foliage crops use of 25-50 percent
nitrate nitrogen is still recommended.

Research has not been conducted on effects of different sources of
other macro- or micronutrients on foliage plant production. Thus, the
major consideration in their selection should be their effect on pH and
availability of nutrients.

FERTILIZER APPLICATION FREQUENCY

Liquid fertilizers should be applied frequently at relatively low
rates at each irrigation or no more infrequently than weekly. The
fertilizer should be supplied near the end of the irrigation cycle to
reduce leaching. This method will supply needed nutrients to plants while
limiting the amount of fertilizer ions that can be leached during heavy
rainfall.

Slow-release fertilizers have a specified release period, such as 2 to
4, 3 to 4, 8 to 9, and 9 to 12 months or more. The release rate for slow-
release fertilizers is usually calculated for a soil temperature near 700F,
but may be based on a higher soil temperature depending on the
manufacturer. During periods when potting media are near 650F or lower,
the release rate will be slower; if temperatures reach 80 to 1000F, the
release rate will be much faster. These factors must be considered when
using slow-release fertilizers in Florida since release rate of a 3 to 4
month material may be 2 to 3 months in the heat of summer or 4 to 5 months
during a cool winter. Placing containers pot-to-pot or spacing plants only
when some canopy has developed will reduce soil temperatures; also, actual
soil temperatures under shade structures (40% shade or greater) are usually
about 100F cooler than in full sun so these factors should be considered
when selecting slow-release sources.








Tailor the slow-release fertilizer release period to the crop cycle to
reduce the potential for leaching and incorporate the fertilizer to prevent
losses of granules from containers. Do not overfill containers at time of
potting since this will increase the chance of granular materials falling
off the medium surface if fertilizer reapplication is necessary. These
precautions will decrease the potential for leaching and make this the most
efficient choice of the available fertilizers both in terms of decreasing
pollution potential and in getting the most for your fertilizer money.

FERTILIZER RATES

Suggested rates for various areas, pot sizes and sources are shown in
Tables 5-8. If fertilizer is to be applied as a ppm solution, check rates
against footnotes on Tables 5-6. Suggested N, P and K levels in ppm for
continuous application are 150 ppm N, 50 ppm P20, and 100 ppm K20 (150 ppm
N, 22 ppm P and 83 ppm K).









Table 1. Suggested light and nutritional levels for production of some potted
acclimatized foliage plants in Florida. a


Light intensity Shade cloth Fertilization
Botanical name (foot-candles) (percent) category


Aeschynanthus pulcher
Aglaonema (cultivars)
Anthurium (cultivars)
Aphelandra squarrosa
Araucaria heterophylla
Asparagus (species & cultivars)
Beaucarnea recurvata
Brassaia (species & cultivars)
Bromeliads (species & cultivars)
Calathea (species & cultivars)
Chamaedorea elegans
Chamaedorea erumpens
Chlorophytum comosum
Chrysalidocarpus lutescens
Cissus rhombifolia
Codiaeum variegatum
Cordyline terminalis
Dizygotheca elegantissima
Dieffenbachia (species & cultivars)
Dracaena deremensis (cultivars)
Dracaena fragrans (cultivars)
Dracaena marginata
Dracaena other species
Epipremnum aureum
Ficus benjamin (cultivars)
Ficus elastica (cultivars)
Ficus lyrata
Fittonia verschaffeltii


1500-3000
1000-2500
1000-2000
1000-1500
4000-8000
2500-4500
2000-4000
3000-5000
2000-3000
1000-2000
1500-3000
3000-6000
1000-2500
4000-6000
1500-2500
3000-8000
1500-3500
2000-4000
1500-2500
2000-4000
2000-4000
3000-6000
1500-3500
1500-3000
4000-6000
4000-8000
2000-6000
1000-2500


70 80%
80%
80%
80 90%
30 60%
50 70%
60 80%
50 70%
70 80%
80%
70 80%
40 70%
70 80%
40 60%
70 80%
30 70%
70 80%
60 80%
70 80%
60 80%
60 80%
40 70%
70 80%
70 80%
40 60%
30 60%
40 80%
80%









Hedera helix (cultivars)
Howea forsterana
Hoya carnosa
Maranta (species & cultivars)
Monstera deliciosa
Nephrolepis exaltata (cultivars)
Peperomia (species & cultivars)
Philodendron scandens oxycardium
Philodendron selloum
Philodendron (species & cultivars)
Pilea spp.
Pittosporum tobira
Podocarpus spp.
Polyscias (species & cultivars)
Radermachera sinica
Saintpaulia ionantha
Sansevieria (species & cultivars)
Schefflera arboricola
Schlumbergera truncata
Spathiphyllum (cultivars)
Syngonium podophyllum
Yucca elephantipes


1500-2500
2500-4000
1500-3000
1000-3500
2000-4000
1500-3000
1500-3000
1500-3000
3000-6000
1500-3500
1500-2500
3000-6000
3000-6000
1500-4500
1500-3000
1000-2000
1500-6000
1500-3000
1500-3000
1500-2500
1500-3000
3000-5000


70 80%
60 80%
70 80%
60 80%
60 80%
70 80%
70 80%
70 80%
40 70%
60 80%
70 80%
40 70%
40 70%
50 80%
70 80%
80%
40 80%
70 80%
70 80%
80%
70 80%
50 70%


ZRate in g N/ft2/yr using a 3-1-2 (N-P20 -K O) ratio fertilizer to supply P and K.
Categories are defined as 1 = 10 g, 2 = 13 g, 3 = 16 g, 4 = 19 g and 5 = 22 g
N/ft /yr.








Table 2.
change


Approximate amount of incorporated materials required to
pH of potting mixtures.


Dolomitic lime (pounds per cubic yard) or equivalent
amount of liming material to raise pH of indicated
medium to approximately 5.7.


50% Peat 50% Peat
Beginning + + 100% Peat
pH 50% Sand 50% Bark


5.0 1.7 2.5 3.5
4.5 3.7 5.6 7.4
4.0 5.7 7.9 11.5*
3.5 7.8 10.5* 15.5*


Sulfur (pounds per cubic yard) needed to lower pH of
indicated media to approximately 5.7.


50% Peat 50% Peat
Beginning + + 100% Peat
pH 50% Sand 50% Bark


7.5 1.7 2.0 3.4
7.0 1.2 1.5 2.5
6.5 0.8 1.0 2.0


*Addition of more than 10 pounds of dolomite per cubic yard often
causes micronutrient deficiencies.








Table 3. Suggested application rates
foliage plants.


of micronutrients for


Rate of application
Element gm/1000 sq ft/mo gm/1000 sq ft/yr lb/A/yr

Boron (B) 0.43 5.2 0.50
Copper (Cu) 4.33 52.0 5.00
Iron (Fe) 17.33 208.0 20.00
Manganese (Mn) 8.67 104.0 10.00
Molybdenum (Mo) 0.02 0.2 0.02
Zinc (Zn) 4.33 52.0 5.00


Table 4. Amounts of 9-3-6 fertilizer needed to supply suggested fertilizer
levels in various sized pots for specific crops (see Table 3).

Fertilizer lb 9-3-6/1000 grams2 9-3-6/pot/month grams 9-3-6/
category' sq ft/month 4" 6" 8" 10" 12" 14" sq ft/month3

1 19.14 5 0.8 1.7 3.0 4.7 6.8 9.2 8.7
2 25.6 1.0 2.3 4.0 6.3 9.1 12.3 11.6
3 31.9 1.3 2.8 5.1 7.9 11.4 15.4 14.5
4 38.3 1.5 3.4 6.1 9.5 13.6 18.5 17.4
5 44.6 1.8 4.0 7.1 11.1 15.9 21.6 20.3

Categories are defined as 1 = 10 g, 2 = 13 g, 3 = 16 g, 4 = 19 g and 5 = 22 g
N/ft /yr.
One teaspoon 9-3-6 equals approximately 5 gms.
3Use to calculate rates for larger containers.
4If fertilizing with each irrigation is desired, divide by expected number of
irrigations during the month.
One quarter inch of 100 ppm N applied ten times monthly equals approximately
12.8 lbs 9-3-6/1000 ft .








Table 5. Amounts of 20-20-20 fertilizer needed to supply suggested fertilizer
levels in various sized pots for specific crops (see Table 3).

Fertilizer lb 20-20-20/ grams2 20-20-20/pot/month grams 20-20-20/
category' 1000 ft2/month 4" 6" 8" 10" 12" 14" sq ft/month3

1 8.64'5 0.4 0.8 1.4 2.1 3.1 4.1 3.9
2 11.5 0.5 1.0 1.8 2.8 4.1 5.5 5.2
3 14.4 0.6 1.3 2.3 3.5 5.1 6.9 6.5
4 17.2 0.7 1.5 2.7 4.3 6.1 8.3 7.8
5 20.1 0.8 1.8 3.2 5.0 7.2 9.8 9.2

Categories are defined as 1 = 10 g, 2 = 13 g, 3 = 16 g, 4 = 19 g, and 5 = 22 g
N/ft /yr.
One teaspoon 20-20-20 equals approximately 5 gms.
Use to calculate rates for larger containers.
If fertilizing with each irrigation is desired, divide by expected number of
irrigations during the month.
One quarter inch of 100 ppm N applied ten times monthly equals approximately
6 lbs 20-20-20/1000 ft2.


Table 6. Amounts of 14-14-14 Osmocote' needed to supply suggested fertilizer
levels in various sized pots for specific crops (see Table 3).

Surface application
Fertilizer grams3/pot/3 months
category2 4" 6" 8" 10" 12" 14" grams/ft2/3 months4

1 1.5 3.3 5.8 9.1 13.1 17.8 16.8
2 1.9 4.4 7.8 12.2 17.5 23.7 22.3
3 2.4 5.5 9.7 15.2 21.9 29.6 27.9
4 2.9 6.6 11.7 18.2 26.3 35.6 33.5
5 3.4 7.7 13.6 21.3 30.6 41.5 39.1

SSulfur coated slow-release formulations can be substituted at equivalent
rates. For urea formaldehyde slow-release formulations increase rates by 25%
or more.
2Categories are defined as 1 = 10 g, 2 = 13 g, 3 = 16 g, 4 = 19 g, and 5 = 22 g
N/ft /yr.
One level teaspoon = approximately 5 gms.
4Use to calculate rates for larger containers.


0








Table 7. Amounts of 19-6-12 Osmocote1 needed to supply suggested fertilizer
levels in various sized pots for specific crops (see Table 3).


Surface application
Fertilizer grams3/pot/3 months
category2 4" 6" 8" 10" 12" 14" grams/ft2 /3 months4

1 1.1 2.4 4.3 6.7 9.6 13.1 12.3
2 1.4 3.2 5.7 8.9 12.9 17.4 16.4
3 1.8 4.0 7.2 11.2 16.2 21.8 20.5
4 2.2 4.8 8.6 13.5 19.4 26.2 24.7
5 2.5 5.7 10.0 15.7 22.6 30.6 28.8

1Sulfur coated slow-release formulations can be substituted at equivalent
rates. For urea formaldehyde slow-release formulations increases rates by
25% or more.
2Categories are defined as 1 = 10 g, 2 = 13 g, 3 = 16 g, 4 = 19 g and 5 = 22 g
N/ft /yr.
One level teaspoon = approximately 5 gms.
Use to calculate rates for larger containers.








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