ANTHURIUM PRODUCTION, PLANT NUTRIENTS AND FERTILIZERS

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ANTHURIUM PRODUCTION, PLANT NUTRIENTS AND FERTILIZERS

Celeste Whitlow

March 2003

The anthurium has unique cultural requirements and considerations, varying depending on the specific growing environment. A fertilizing program to meet the Anthurium=s nutrient requirements should be developed after consideration of these cultural requirements and the several variables involved in anthurium production.

VARIABLES RELATED TO FERTILIZER CHOICE

Growing medium. A wide range of recommendations exist regarding the media in which anthurium are grown (from soil-less mixes of volcanic rock to ratios of peat moss (or other organic material such as compost, coir, or leaf mould, manure, and Perlite). The grower=s choice of growing media will require adjusting the fertilizing program to supply nutrients optimally accessed by the anthurium, over the duration of its residence at the grower=s facility, in the media in which it is grown. If a soil-less medium is used, unplanned leaching should not occur because it is an inefficient use of purchased fertilizers and increases production costs, because it makes the nutrients unavailable to the plant, and because it can contaminate groundwater supplies and bodies of water into which the irrigation water drains. Because soil-less media do not have the CEC sites to hold onto the nutrients, a fertilizing program should be designed with the rate at which nutrients are applied not exceeding the ability of the media to retain the nutrients long enough for the anthurium to access it.

Varied desired results Anthurium are grown commercially with varied goals:

1. To harvest the flowers to sell, requiring the flowers be of optimum quality and able to withstand the rigors of packaging and transport.

2. To be sold as potted plants, requiring compact, robust growth, withstanding the rigors of transport and sometimes packaging, and the acclimatization to the interior-environment growing conditions provided by the end buyer.

3. To be used as stock plants for either cut-flower production or as mother stock for propagation.

Therefore, the crop=s nutrient needs and the timing and rate of the delivery of the nutrients will vary depending on the desired end product.

Light intensity The recommended light intensity for anthurium depends on the species. Generally, 1000 to 2500 foot-candles is recommended. If anthurium are grown at lower-than-optimal light levels, then the photosynthesis and respiration will be less than normal. Therefore, their nutrient requirement will be lower.

Temperature Temperatures in the growing environment less than 60 to 65 degrees F will slow the anthurium=s physiological processes below normal, and the anthurium will require less nutrients. Temperatures higher than 86 degrees F will increase the physiologic processes beyond normal, and the anthurium will require more nutrients.

Soil pH Oglesby Plants International (which commercially produces micropropagated anthurium for growers) recommends an anthurium media pH of 5.5-6.5. This pH range does not usually produce nutrient toxicities, deficiencies, or a marked decrease in numbers and activity of soil microorganisms. However, if the medium pH dropped below 5.5 (or became alkaline) then the soil microbial numbers and activity would decrease, and the onset of nutrient toxicities or deficiencies would be expected. Therefore, careful media pH control is necessary.

Sensitivities Anthurium are very sensitive to high-salt levels and supraoptimal copper levels. These sensitivities limit both the types of fertilizers able to be utilized, and the fungicides which can be applied.

Special nutrient requirements The anthurium requirement for magnesium is higher than for most other foliage plants, and production experiences decreased growth, flower production, and appearance with suboptimal magnesium availability. Magnesium-containing fertilizers should be included in the fertilizer program for anthurium.

Long-term nature of the crop Anthurium is considered a long-term potted-plant production crop, requiring months to years to reach marketable size, depending on the cultivar and the method of propagation. This requires planning for fertilizing over an extended period of time, and balancing the need for long-term fertilizing, labor costs involved in administering the fertilizer, the cost of the fertilizer used (slow-release fertilizers usually being more expensive than other fertilizers), avoiding drift of the media pH out of acceptable range, and salt accumulation in the media which can easily occur when a plant in the same pot and media over months to years is fertilized on a regular basis. Other anthurium production scenarios include mother-stock plants kept permanently at the grower=s facility, either for cut-flower or propagation purposes. These plants would require a long-term salt- and pH-sensitive fertilization program.

Anthurium culture challenges Anthurium require very well-draining media, and regular irrigation for maximum growth. They are grown in a humid (40 % relative humidity recommended) environment. The recommended minimum temperature is around 60 degrees F, and the maximum recommended temperature is 86 degrees F. In addition, anthurium are susceptible to damage from pathogens (bacteria, fungi and viruses) either water-borne, or quickly reproducing and spreading in a high-humidity and tropical-temperature environment, especially one having standing water. Indeed, even splashing water can transmit the pathogens causing diseases, damaging anthurium. In summary, the conditions for growing anthurium provide an environment with a high potential for the growth of pathogens, the development of plant diseases, the leaching of applied fertilizers, the accumulation of salts in the media, and the development of suboptimal media pH levels. These cultural challenges limit the choices of fertilizer application methods.

General fertilizer considerations

< If the anthurium are grown in a soil-less or low-soil media, careful fertilizer management is required to avoid leaching. Without the cation exchange capacity sites to hold on to the applied nutrients, nutrients can easily be leached secondary to the frequency of irrigation occurring and the well-draining nature of the media.

< Soil-less or low-soil media have few to no microorganisms necessary to convert some fertilizer plant nutrients into forms the plant can use. In particular, forms of nitrogen and phosphorus applied to the media are largely unavailable to the plant without the microorganisms to convert them into plant-available forms.

< In soil- or organic-material-containing media, microorganism numbers and activity (and, therefore, conversion of fertilizer to plant available nutrients) may be inhibited by some pesticides, a low pH level of the media, impaired drainage/poor aeration of the media, and increased soluble salts in the media.

< Media allowed to become excessively acidic or alkaline may make micronutrients either unavailable, or available at toxic levels.

< Media allowed to become excessively acidic (especially when micronutrients are applied) can produce toxic levels of manganese and iron.

< If the anthurium are grown in media containing soil or organic material, high-salt fertilizers (if used) should be carefully managed to avoid damage to the salt-sensitive plants.

< Excessive levels of nutrients can occur after steaming organic-material-containing media, especially manure-containing media producing high levels of ammonium. Recycled media previously fertilized with sustained-release fertilizers, when steam-sterilized, can produce elevated levels of all of the nutrients contained in the fertilizer. In addition, steaming the media can release excessive levels of manganese.

< Ammonium is positively charged making it less prone to leaching. However, nitrification occurs (under adequate conditions) rapidly, unless the medium was steam sterilized.

< When considering the three forms of nitrogen usually found in fertilizers (urea, ammonium and nitrate), urea is usually the least expensive.

< For potted-plant production, acclimatization to environmental conditions the buyer will be able to provide is an important consideration. While various factors are related to acclimatization, light intensity and fertilizer choice and application are the most important. Plants have a decreased ability to adjust to interior environments (the destination of the majority of potted anthurium sold) when they receive high levels of nitrogen during production.

< Adjustment of the pH level of the media should be done before the anthurium is potted.

< The soluble salt level of the medium used should be determined before it is used in production because high-salt media will require a specialized fertilizer program to avoid excessively increasing the medium salt level by the addition of fertilizer ions.

< If liquid fertilizer is used to avoid leaching, it should be applied toward the end of the irrigation cycle, and frequent applications of low-concentration fertilizer is recommended.

< If foliar applications are utilized, the fertilizing should be done early in the day and air movement temporarily increased (or humidity decreased) after the application (if possible) to hasten drying of the foliage.

< If fertilizer intended for the media is part of an overhead irrigation program, the foliage should be rinsed afterwards to prevent foliage damage.

< If slow-release fertilizers with temperature-dependent release are used, the effective time period may need to be extended if the crop cycle includes an extended period of overall reduced temperatures (for example, during the winter).

< Anthurium require higher levels of magnesium than do most foliage plants, and consistent applications of magnesium fertilizer is recommended. The regular addition of magnesium may require additional applications of calcium to ensure an appropriate calcium-magnesium ratio is maintained in the media.

In summary, if solid fertilizer is utilized to avoid leaching, elevated salt levels and changes in media pH levels, frequent applications of low-concentration fertilizer is recommended. This approach will increase labor costs. Overhead irrigation (the easiest and least expensive fertilizer application method) is not recommended because of the potential for growth and spread of water-borne or water-encouraged pathogens and diseases. If liquid fertilizer is utilized, and overhead irrigation is not used, if delivery is by other irrigation means, low-concentration/higher-frequency applications are recommended. Care should be taken to avoid leaching of the fertilizer. If liquid fertilizer is applied as a separate process, labor costs are increased. If overhead irrigation is to be avoided, and foliar application (which is often recommended because of the media=s inability to hold on to the nutrients supplied by the fertilizer for an extended period of time) is selected as a method of fertilizer application, fertilization must be done as a separate process, increasing the labor costs involved. The use of inorganic sustained-release fertilizers would avoid wetting the foliage (decreasing the potential for disease), and decrease the labor costs involved in application, but the cost of the fertilizer is higher than the cost for liquid or solid fertilizers. The extent of the release time should be noted to ensure re-application is performed on the appropriate date to avoid plant nutrient deficiencies. The use of organic sustained-release sources of plant nutrients (for example, manure) is not practical for anthurium because of the potential for salt toxicity, the variance of material (and salt) content and the rate of release, and the efforts involved in re-applying the material during the long production period.

Fertilizer recommendations Recommendations for fertilizers vary, depending on the source and the anthurium end-product. The following are recommendations do not conflict with either other referenced sources or anthurium physiology.

Cut-flower production

Sri Lanka Department of Agriculture.

Soil-less or low-soil/organic-material media Nitrogen is recommend at a P₂O₅: K₂O ratio of 20:20:20 during vegetative growth, and 6:14:7 or 20:30:20 during flowering. Fertilizers containing micronutrients (including calcium and magnesium) should be added in liquid form ACropmaster@ or AMaxicrop@) (Anthurium, Sri Lanka Department of Agriculture).

Soil- or organic-material-containing media Applications of solid fertilizer containing ammonium sulfate (30 kg), superphosphate (55 kg) and muriate of potash (15 kg), with each potted plant receiving 8 g of this mix, is recommended (Anthurium, Sri Lanka Department of Agriculture).

With this program, from the same planting, cut flowers can be harvested 1.5 years after planting the mother-stock anthurium plant, with continuous harvesting over a 5-year period of time. Annual flower production (starting the second year) is reported to be:

< Second year: 250,000 flowers per hectare.

< Third year: 300,000 flowers per hectare.

< Fourth year: 350,000 flowers per hectare.

< Fifth year: 350,000 flowers per hectare.

Potted-plant production

University of Maryland, College of Agriculture and Natural Resources Well-drained material containing wood products in the mix is recommended. Based on this media, they recommend

< Nitrogen applications at 200 ppm N, in a 1-2-2 ratio, or use a sustained-release fertilizer.

< Magnesium supplied by either one application of magnesium sulfate to the substrate (2 to 4 pounds per cubic yard of media); monthly applications of 1 to 3 pounds magnesium sulfate per 100 gallons of irrigation water; dolomitic limestone as part of the substrate media; magnesium provided in a complete fertilizer (13-2-13, 14-0-14, 15-15-15, or 17-0-17) (Production/Postproduction Factors for Anthurium. University of Maryland, College of Agriculture and Natural Resources).

University of Florida, Institute of Food and Agricultural Sciences In the article Light intensity and fertilizer recommendations for production of acclimatized potted foliage plants, very detailed recommendations are given for each macronutrient and micronutrient. Several fertilizer grades, (including slow-release Osmocote) for a large number of foliage plants (including anthurium), with specifics given for each type of plant, are recommended. In addition, specific recommendations are given for adjusting pH levels to 5.7, with specific suggestions for different types of media, and beginning pH levels. Based on their recommendations of 1000 to 2000 foot-candles light intensity and 80 % shade cloth, they make very detailed recommendations for each nutrient and micronutrient, calibrated to pot size. This website (http://mrec.ifas.ufl.edu/Foliage/Resrpts/rh_95_2.htm) presents a clear presentation of this extensive collection of data.

In the publication entitled Effects of nitrogen and potassium fertilization ratios on growth and flowering of three anthurium hybrids, the highest quality plants (improved flowering, and overall appearance of plants) were produced by the fertilizers containing lower nitrogen and potassium levels. The flowering of the plants at lower levels of the two nutrients, depending on the cultivar, was rated as 59% to 85% improved. The lack of early flowering often experienced by growers (based on the data) may be due to excessive fertilizer nutrient levels (especially nitrogen). They recommended 900 to 1200 pounds of nitrogen per acre per year from a fertilizer with a 1:1:1 ratio (such as a liquid 20-20-20 or Osmocote 14-14-14 slow-release fertilizer). (C.A. Conover, Ph.D. and R.J. Henny, Ph.D. Effects of nitrogen and potassium fertilization ratios on growth and flowering of three anthurium hybrids. University of Florida, Institute of Food and Agricultural Sciences.)

Oglesby Plants International Oglesby is a well-known provider of tissue-culture plants, including anthurium. They have been on the forefront of solving the challenges inherent in producing tissue-culture plants, and processing them to the point where the grower purchasing them can successfully transition them to the growing greenhouse facility. Oblesby recommends fertilizing with a complete fertilizer at a consistent, moderate level. Because the anthurium is considered a long-term production crop, and because magnesium requirements for anthurium are higher than for other foliage plants, continued availability of magnesium to the plant is important. They recommend adding dolomite (10 pounds) and Hi-Cal lime (3.5 pounds per cubic yard) to the media. Foliar applications of magnesium fertilizers (such as Epsom Salts) should be made on a regular basis. High nutrient levels (especially after planting young plants) should be avoided. About 300 to 400 ppm nitrogen at frequent doses produces slower growth, lighter colors of the flowers, and thick, deformed leaves. If liquid fertilizers are utilized on a constant-feed program, applications of nitrogen not higher than 250 ppm. Older plants can tolerate up to 400 ppm of nitrogen occasionally, but applications should be alternated with watering. If using dry fertilizer, watering frequently to avoid salt accumulation. If slow-release fertilizers are used, they should be applied and the release-time tracked to avoid nutrient deficiencies.

SUMMARY The anthurium as a production crop presents various challenging growing conditions. These include the long-term nature of the crop, the salt sensitivity and special nutrient requirements, and a specific growing environment limiting both the type of fertilizer used and the manner in which it is applied. A fertilizer program should be carefully designed and conducted to address these growing conditions, and produce a profitable, marketable crop.

References:

C.A. Conover, and R.J. Henny. 2003. Effects of nitrogen and potassium fertilization ratios on growth and flowering of three anthurium hybrids. University of Florida, Institute of Food and Agricultural Sciences. ((http://mrec.ifas.ufl.edu/Foliage/Resrpts/rh_95_2.htm)

Anonymous. 2003a. Light and fertilizer recommendations for production of acclimatized potted foliage plants. University of Florida, Institute of Food and Agricultural Sciences

(http://mrec.ifas.ufl.edu/Foliage/Resrpts/rh_90_1.htm)

Anonymous. 2003b. Nutrient disorders, other noninfectious factors. The American Phytopathological Society. (www.apsnet.org/online/feature/abiotic/nutrition.html)

Anonymous. 2003c. Anthurium. Oglesby Plants International.

(http://www.oglesbytc.com/Culture/Anthurium/htm)

Anonymous. 2003d. Anthurium. Sri Lanka Department of Agriculture

(www.agridept.gov.lk/Techinformations/Floricuulture/anthuri.htm)