ANTHURIUMS
Anthuriums have been cultivated for many decades for cut flower
production. Since the mid 1980's, Anthurium's popularity as a flowering pot plant has
increased dramatically and has become a popular addition to many foliage growers' product
lines. 
Anthuriums are relatively easy to grow, have attractive foliage
and under the proper environment, produce long lasting flowers year round. Currently
numerous cultivars with different flower sizes, shapes, colors and some with delicate
fragrances are available for the consumer. Commercially, pot type Anthuriums are grown throughout
the world with the heaviest concentrations in the United States (Florida) and The
Netherlands.
4 Basic Groups
Anthuriums can be divided into four basic groups; A. andreanum cultivars,
inter-specific hybrids between A. andreanum cultivars and dwarf species currently referred
to as 'Andreacola' types, A. scherzeranum hybrids, and foliage Anthuriums. Anthurium
andreanum, a generally large, somewhat open structured plant with large flowers is
commonly grown for cut flower production and sometimes adaptable to pot culture. New
andreanum cultivars, selected specifically for pot culture are more compact. A. andreanum
primary flower colors are white, pink, red, red-orange and green. 'Andreacola' cultivars
are small to intermediate in overall size, fuller, more compact and generally produce
smaller but more numerous flowers than andreanum cultivars. 'Andreacola' cultivars tend to
have thicker, dark green leaves and many times show resistance to the more aggressive
Anthurium diseases. Primary flower colors are white, pink, red and lavender. A.
scherzeranum, the first widely cultivated Anthurium pot plant, is a small, compact plant.
Primary flower colors are white (sometimes with polka-dots), pink and red. Foliage
Anthuriums come in numerous shapes and sizes and represent a minor portion of the total
Anthurium pot market. However, it should be noted that most foliage Anthuriums are durable
plants and offer the consumer distinct forms.
HABITAT
Most Anthurium species are native to tropical rain forests and are primarily epiphytic
in nature. Thus, in their natural habitat, they receive ample, frequent water with good
drainage. In cultivation, Anthuriums prefer evenly moist media especially when actively
growing. Overall, it is better to slightly underwater than overwater. Drying out may cause
tip burn, root damage and reduced growth rates while over watering can also cause root
damage and sudden yellowing of older leaves. 
Anthurium will not tolerate saturated, poorly drained soil mixes. Best
results are achieved with a 1:1:1 ratio of Canadian peat, composted pine bark (watch for
particle size; not too much dust) and perlite or airlite. Avoid vermiculite except in
4" containers. In long-term crops, i.e., 6" and up, vermiculite compacts and
will water-log. Soil pH should be maintained between 5.5 and 6.5.
FERTILIZER
Moderate but consistent levels of a complete fertilizer are important. Magnesium
requirements in Anthurium plant tissue are higher than most foliage crops especially in
warmer climates. Because of the long-term nature of Anthurium crops, special attention
must be paid to ensure continued availability of Magnesium. Per cubic yard of soil,
incorporate 10 lbs. of dolomite and 3 ½ lbs. Hi-Cal lime to balance the Calcium and
Magnesium ratio. Regular foliar applications of Magnesium sources (Epsom Salts, Magnesium
Nitrate, etc.) will help prevent Magnesium deficiencies. After 24-26 weeks, a top-dressing
of dolomite (3 tbsp/l0" pot) or another Magnesium source will help insure continued
availability of Magnesium. Top-dressings of Epsom Salts are beneficial but short-lived.
Avoid high nutrient levels especially after planting young plants. Liquid fertilizer on
a constant feed program should not exceed 250 ppm Nitrogen (N). On mature plants,
occasional rates as high as 400 ppm N are acceptable, but must be alternated with
watering. Tests have shown that plants given frequent doses of 300-400 ppm N grow slower,
have lighter flower colors and produce thick deformed leaves. When using overhead
irrigation system to dispense liquid fertilizer, a quick rinse with pure water is
beneficial since liquid fertilizer left on foliage can damage leaves causing grayish corky
scars. With dry fertilizer applications, it is very important to water frequently to
reduce salt build-up. When using time-release fertilizers, carefully consider crop times
and if necessary reapply to avoid deficiencies.
Anthuriums grow best with day temperatures of 78 to 90oF, and night temperatures of 70
to 75oF. Temperatures above 90o F may cause foliar burning, faded flower color and reduced
flower life. Night temperatures between 40 to 50oF can result in slow growth and yellowing
of lower leaves. Scherzeranum cultivars require lower temperatures in the range of 68 to
80oF daytime and 60 to 70oF nights. Anthuriums will not tolerate frost or freezing
conditions.
LIGHT
Anthuriums grow under a wide range of light intensities but their actual performance is
dependent on the cultivar, elevation, temperature and nutrition. Generally, most Anthurium
types grow well at light intensities ranging from 1,500 to 2,500 foot candles (fc). Light
intensities higher than 2,500 fc can improve branching habits (i.e., fullness) but can
result in faded flower and leaf color. Some growers use light intensities between 3,600
and 4,000 fc during the early crop stage to improve branching and then move the crop to
lower light intensities for finishing. Scherzeranum cultivars are best grown at light
intensities between 1,000 and 1,500 fc.
DISEASE & PEST
Preventive maintenance programs for mites, snails, slugs, worms, thrips and white flies
are important. White flies are especially attracted to the new growth and once established
are difficult to eradicate. A number of chemicals are effective for pest management,
however, cultural conditions and cultivars will determine what you can use safely. Many
growers have experienced phytotoxicity on numerous Anthurium cultivars from the use of
certain pesticides. Never apply pesticides while plants are under any form of stress,
i.e., moisture or hot temperatures.
Anthurium andreanum cultivars are generally susceptible to bacterial blight,
Xanthomonas campestris pv 'dieffenbachiae'. This very aggressive disease starts as foliar
necrosis eventually leading to a systemic infection. There are no effective chemical
controls for blight although copper sprays and good sanitation practices may have some
efficacy in prevention. Xanthomonas is spread by excessive water, splashing, and contact
with infected plants or tools. Susceptible cultivars may perform best under hard cover
with drip irrigation and very well drained media. Good ventilation is necessary to allow
rapid drying of foliage.
'Andreacola' cultivars are generally resistant to Xanthomonas, however, they are
somewhat susceptible to Phytophthora, Rhizoctonia, Pythium and Colletotrichum. Although
there are a number of effective fungicides for these diseases (we have not seen
phytotoxicity from proper use of the popular chemicals available), the best approach is
prevention via cultural practices. Keep plants off the ground, provide good ventilation
and avoid overhead irrigation during late afternoon or evening hours. As a matter of
caution, all new pesticides should be used in a controlled test on a small percentage of
each cultivar grown. Always allow four weeks for phytotoxic symptoms to appear.
PROPAGATION
Young plants are primarily propagated by tissue culture and available commercially
either as microcuttings or as 72 or 98 cell liner trays. Depending on the cultivar's
inherent branching and flowering habit, young plant producers use one to three plants
(microcuttings) per liner cell. Cultural conditions, especially light intensity, are very
important for young plant production. Finish growers should avoid using young plants grown
under low light conditions.
CONTAINER GROWING
Most pot Anthuriums are sold in 6" and 8" containers, with a smaller
percentage in 4 and 10 inch. Crop finish times will vary depending on cultivar, pot size
and cultural environment. Except in the case of scherzeranum, growers should consider
Anthurium a long term floral crop. Under the subtropical climate of Florida, most 6"
container crops are finished in 8 to 10 months using 72 or 98 cell tray young plants.
Scherzeranum is usually grown in 3 ½" to 6" containers and will finish in 4 to
7 months. A young plant supplier will be able to give recommendations on the optimum
container size and finish times for each individual cultivar.
Since their introduction, potted Anthuriums have generated a great deal of excitement
at retail and with the end user. Anthuriums are durable and will survive as an indoor
foliage plant for a remarkable period of time, even under adverse conditions. The big plus
of course is the added canopy of color. If the last few years are any indication,
Anthuriums as flowering pot plants will continue to grow in popularity. As a result of
breeding programs, new and improved cultivars will be introduced which will help
Anthuriums gain additional market share.
