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Copyright 2005, Board of Trustees, University
INFLUENCE OF NUTRITION ON FOLIAGE QUALITY AND LONGEVITY
Charles A. Conover
Agricultural Research Center Apopka
Mimeo Report ARC-A 1972-3
Nutrition of tropical foliage plants has a major influence on growth
rate, quality and longevity. Growth rate has a major effect on profit
of a particular foliage plant to growers and ultimate o p ?nwr "
Therefore, slow growing varieties cost more because t y utilize labor
and space for a larger time span and growers increase fertility levels
to reduce production costs. Quality of foliage plants ks also vqer oF
important, because appearance is a prime factor in stimulat4nghtl aes.
The appearance, can be altered considerablyby fertilization, which
influences plant and leaf size as well as color.
Longevity of foliage is of prime interest to consumers and determines
consumer satisfaction, and therefore, repeat sales. During the first
few months in the home, plants are influenced to a considerable degree
by the fertility regimes of the grower and can affect longevity. Growth
rate, quality and longevity of foliage plants may be increased or decreased
by changing nutrition. Therefore, for any given situation there is a
desirable nutritional range that will provide the grower and consumer
Maximum growth rate can be obtained with many foliage plants with high
levels of soluble, organic or slow-release fertilizers. Unfortunately,
very high levels produce root/shoot ratios of less than one, and result
in a plant with a large top, foliage or long vines and a small root system.
'"Under -condition of high humidity-and frequent -atering -such..plants .will
become attractive .and_ appear-to be. of high quality. However.,.when these.
.plants-are placed under low humidities of most building.interiors,...many
older lower. leaves will become yellow and drop. This leaf drop will.occur
* .-even though soil moisture .is...satisfactory, because inadequate root systems
cannot maintain proper moisture levels within plant tissue. Therefore,
the most satisfactory nutritional level for the growers profit margin does
not always produce the best quality plant for the consumer. On the other
hand, consumers are generally not willing to pay the additional price of
small plants with proper root/shoot ratios.
The appearance of a plant is an important index of its quality.
Research at the Agricultural Research Center at Apopka and the University
of Florida has shown that medium to high levels of nitrogen and potassium
are necessary for proper color and leaf size. At the same time, other
important major and minor elements must not be neglected or "Quality" will
be lost because of small leaves, chlorosis or necrosis. Generally,
deficiencies of magnesium and iron are common and must be provided in the
fertilizer program. More recently, we have found fluoride toxicities in
Cordyline. These examples point out the possibility of reductions in plant
quality if positive nutritional programs are not established.
Buyers and consumers would like foliage plants to last forever,
even in a dark corner, while producers know this isn't possible. The
main point,- however, is that foliage plants should be expected to provide
consumers pleasure for three to six months, even under the poor growing
conditions. Light level is the most important requirement for longevity of
foliage, but it may also be severely influenced by soluble salt levels
within the growing medium. Under grower conditions where the soil medium
is moist at all times the soluble salts present from fertilizers and water
are generally not influencing quality adversely. However, once moved
into the market place or home, plants may be allowed to dry or wilt and
severe root damage from salt burn may result.
Calculation of soluble salts are based on the moisture percentage of
the growing medium. A salt level in moist soil of 2000 parts per million
(ppm), would not cause injury to most foliage plants, but if allowed to
wilt, or the soil to become dry the soluble salt level will double or
triple. These higher levels will severely damage root systems and can
predispose them to disease organisms or prevent absorption of nutrients
and water. Symptoms of injury from soluble salts on foliage plants in
the home may appear as marginal leaf ehlorosis or necrosis of newer leaves
and yellowing and dropping of older leaves.
Research to date indicates that there is no single source or level of
fertilizer that will do the best job under all situations. However, there
are average levels that will produce quality potted foliage plants provided
soils are properly prepared. Suggested materials and levels td use when
mixing potting soils are shown in Table 1.
The main source of nitrogen and potassium as well as supplemental
phosphorus is most frequently soluble forms of fertilizer. However, slow
release materials such as Osmocote are also very desirable. The amounts
of chemical or slow-release fertilizers to use are listed in Tables 2 and
3, and vary for different plant types. Generally, philodendron, pothos
and dracaena require the listed amounts, while dieffenbachia, peperomia,
maranta and syngonium require about two-thirds that amount. If the soil
mixture is prepared according to Tables 1 and 3, fertilizer will not need
to be applied for 3 to 4 months.
Levels higher than those listed in Tables 2 and 3 should not be provided,
or injury from soluble salts may occur. As stated earlier, injury may not
appear in the growing range, but in the home when soils are allowed to become
Table 1. Nutritional amendments and amounts to add
to potting soils for foliage plants.
Material Amount/cu ydI Provides
Perk or Fritted
3 lb or
, Based on soil mixtures containing 50
to 75 percent
Table 2. Liquid fertilizer program for potted foliage plants.
Soluble Lbs/1000 sq
materials Lbs/acre/mo.1'2 ft/mo. Remarks
May be mixed
Nitrogen (N) 167 3.8 from single
Potassium (K20) 167 3.8 20-2-20 may
be used at the
rate of 835 Ib
Phosphorus (.P205) 16.7 0.40 /A/mo or 19 lb/
1000 sq ft/mo.
1Reduce rate by one-third when crops are grown in
more than six months.
the same pot for
2Based on soil mixtures containing 50 to 75 percent acid peat.
Table 3. Slow release fertilizer
program for potted
Materials Lbs/cu yd1,2 Remarks
Osmocote Include in soil
(14-14-14) 10 mixture and delete
lasts 3 to 4 months
Osmocote 9 Ditto
1May be surface-applied after 3 to
may be switched to liquid if crop
4 months to mature.
2Based on soil mixtures containing
4 months, or program
requires more than
50 to 75 percent