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African Violet Care Instructions - Part 2

African Violet Problems & Care   ~  Oprime aquí por el español

 

Fertilizer and Plant Nutrition

Violet Food is a fertilizer specifically labeled for African Violets. A good Violet Food should have approximately equal amounts of the primary nutrients, nitrogen (N), phosphorus (P) and potassium (K).These elements are normally found on the front label and will appear, for instance, as 14-12-14, which is the recommended formula for standard African Violets, such as those grown in 3-inch pots or larger. Miniature and super-miniature African Violets, such as those grown in 2-inch pots or less, will typically need a slightly different formula. For those growing Optimara miniatures, a Violet Food or Miniature Plant Food with a 7-9-5 NPK is recommended.

14-12-14 Violet foodAside from making sure your Violet Food has the correct NPK, it is important to consider the source of the elements. Many fertilizers which have been labeled for African Violets, in fact, contain impurities which can be harmful to Violets.

Urea, for instance, is a commonly used source of nitrogen. While it is often cheaper to use than other sources of nitrogen, urea is known to cause Root Burn on African Violets. The damage caused by Root Burn reduces an African Violet's ability to properly absorb water and nutrients. The most obvious signs of this are pale leaves and diminished flowering.
Therefore, when selecting a fertilizer suitable for African Violets, make sure that it does not contain urea nitrogen. This can easily be determined by looking at the Guaranteed Analysis on the fertilizer label. If urea nitrogen is used, it will be listed.

When choosing a Violet Food, make sure that it is 100 percent water soluble. This is important for two reasons. First, if your Violet Food is not 100 percent water soluble, your African Violet may not be able to absorb all its elements. Second, unless your Violet Food is 100 percent water soluble, you cannot use it in a self-watering device. When using one of these devices, elements will only be drawn into the soil if they are fully dissolved.

The primary nutrients, nitrogen (N), phosphorus (P) and potassium (K), represent three of the 16 essential elements needed by African Violets and other plants for normal growth and reproduction. The other 13 essential elements are boron (B), calcium (Ca), carbon (C), chlorine (Cl), copper (Cu), hydrogen (H), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), oxygen (O), sulfur (S) and zinc (Zn). Of these, calcium, magnesium and sulfur are sometimes referred to as secondary nutrients or elements, while carbon, hydrogen and oxygen are often called the free elements, since these are normally obtained from the air and water.

Optimara - The original "St. Paulia" varietiesWhile not all of the essential elements are always listed on the label of a Violet Food, they can generally be assumed to be either included with the formula or available to African Violets in the form of air or water. Each of the essential elements serves an important function. In the absence of any one of these elements, an African Violet would not be able to grow or reproduce properly. Of the primary elements, nitrogen is important for overall growth and the development of green leaves and stems. Phosphorus aids in the production of healthy roots and plays a vital role in the production of flowers. Potassium is necessary for the accumulation and movement of plant carbohydrates, those compounds which give the plant energy.

Of the secondary elements, calcium is important for overall growth and the development of flowers. Magnesium is necessary for the proper function of photosynthesis and the production of chlorophyll. Sulfur plays an important role in the synthesis of proteins and helps boost an African Violet's resistance to disease.

The free elements, carbon, hydrogen and oxygen, are the components of plant carbohydrates which are produced during photosynthesis. Of the remaining seven elements, boron is important for overall growth and the development of flowers. Iron provides a catalyst in the production of chlorophyll. Chlorine, copper, manganese, molybdenum and zinc all play an important role in photosynthesis, while copper also helps to metabolize nutrients into usable energy sources.

In addition to being classified into primary, secondary and free elements, the essential elements are often described as either major elements (sometimes called macronutrients) or micronutrients (sometimes called minor elements). These classifications simply serve to make a distinction between the relative amount that a plant needs of a particular element, not that any of the essential elements are less important than any other. Compared to the major elements, for instance, plants need micronutrients in very small amounts. Altogether, there are nine major elements and seven micronutrients. The major elements are calcium, carbon, hydrogen, magnesium, nitrogen, oxygen, phosphorus, potassium and sulfur. The micronutrients are boron, chlorine, copper, iron, manganese, molybdenum and zinc.

When discussing the elements that may go into a Violet Food, it is important to make a distinction between micronutrients and trace elements. These terms are often confused and mistakenly used interchangeably. In fact, micronutrients are not the same as trace elements. Micronutrients are essential elements; trace elements are not. However, while not considered essential, many trace elements have been determined to provide a beneficial effect to plants. Examples of trace elements, which may provide benefits to African Violets, are cobalt (Co), nickel (Ni), silicon (Si) and sodium (Na).

14-12-14 Violet Food - 1LB BulkViolet Foods come in a variety of forms. Of these, soluble powders and concentrated liquids are most often recommended. Soluble powders are probably the most cost effective in that they do not incur the additional cost associated with the weight of water which is added to concentrated liquids. However, depending on your preferences, both can offer benefits. In addition to being cost effective, soluble powders can be easy to mix, especially when they are packaged in pre-measured pouches. Concentrated liquids, on the other hand, can offer convenience when used with a self-watering device. For instance, because it can be dispensed in drops, Optimara Miniature Plant Food can be applied directly to a MiniWell or WaterShip watering device. In either case, it is important to consider the solubility of the fertilizer. Make sure that your Violet Food is a fully-dissolving fertilizer, even when considering a concentrated liquid. Many make the mistake of assuming that a concentrated liquid must be 100 percent water soluble when, in fact, the accumulation of sediment at the bottom of the bottle clearly suggests otherwise.

In most cases, quick-release fertilizers are preferred to time-release fertilizers (also called slow-release or controlled-release fertilizers). A quick-release fertilizer simply refers to a fertilizer in which all the elements are immediately available to the plant. In contrast, a time-release fertilizer describes a fertilizer in which all the elements are not immediately available. This type of fertilizer is usually formulated into coated granules called prill. While time-release fertilizers are designed to reduce the frequency of application, they make it easy to overfertilize, especially for those who do not have a lot of experience with them. In addition, because the release of nutrients is influenced by various environmental factors, the results can sometimes be unpredictable. Therefore, you are strongly encouraged to avoid using any type of time-release fertilizer. Instead, use a quick-release fertilizer which allows you to fertilize overtime you water. This type of fertilizer will provide your African Violets with a constant supply of the nutrients they need, while significantly reducing the chances of overfertilizing.

Optimara Self-Watering PotMany people, who grow African Violets, are ambivalent as to whether they should use an organic or non-organic fertilizer. This is probably because the term "organic" is so often used in a way that infers "natural." In contrast, anything else is assumed to be "unnatural," i.e., a substance which has been synthesized or somehow chemically manipulated. In fact, both organic and non-organic fertilizers are quite natural. Whereas an organic fertilizer is derived from plant or animal matter, a non-organic fertilizer is simply derived from geological sources, i.e., naturally-occurring minerals. With experience and patience, some growers have succeeded in producing good results with organic fertilizers. However, organic fertilizers tend to be messier to use and often smellier than non-organic fertilizers. Moreover, organic fertilizers do not offer the convenience of non-organic fertilizers. This is because an organic fertilizer, in order to provide all the elements that an African Violet needs, is normally not obtained from one source, but from a combination of sources, such as fish emulsion, manure and tankage (the by-products of slaughtered animals). In addition, organic fertilizers are much more inefficient and frequently less predictable than non-organic fertilizers. By volume, it takes much more of an organic fertilizer to provide the same nutrients that a non-organic fertilizer provides, and because concentrations of the elements can vary widely in organic sources, they cannot provide nutrients in consistent amounts. For these reasons, most growers of African Violets choose non-organic fertilizers. While both are derived from "natural" sources, non-organic fertilizers are easier to use, more efficient and provide greater consistency in terms of both available nutrients and results.

One final consideration in regard to fertilizers is the issue of overfertilizing.
While African Violets need a certain amount of essential elements to grow and reproduce, too much can be harmful. Among other problems, overfertilizing can cause leaves to become cracked or brittle. It may also produce lesions on the leaves and stems. In addition, an overload of certain elements will actually stifle an African Violet's ability to absorb certain other elements. For instance, an excess of magnesium may prevent an African Violet from absorbing enough calcium. Likewise, an excess of either phosphorus or zinc may prevent an African Violet from absorbing enough copper or iron, while an excess of either calcium or magnesium may prevent an African Violet from absorbing enough potassium.
Such imbalances in the elements that are absorbed by African Violets can cause a number of additional problems, such as droopy or chlorotic leaves, leaf tip burn and diminished flowering.

To avoid overfertilizing and the problems associated with it,
always follow the instructions provided with your fertilizer.

In addition, it is important to drench the soil about four times a year (or about every three months). This will wash away any excess fertilizer salts which have accumulated in the soil, while restoring the proper balance of the elements that African Violets need. To leach the soil, simply drench it with water until it has become saturated, and then allow the excess water to drain completely. Finally, if you are using a clay pot, you should routinely wipe the rim with a damp cloth. When plants are overfertilized, excess fertilizer salts often accumulate on the rim of clay pots. When these fertilizer salts come in contact with leaves and stems, they can cause lesions.

African Violet Care
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Copyright 1999-2002 Optimara/Holtkamp Greenhouses, Inc. Nashville, Tennessee. Doctor Optimara, the Doctor Optimara logo and Optimara Field Guide are trademarks of Holtkamp Greenhouses, Inc. Optimara, the Optimara logo, EverFloris, MiniWell, MaxiWell, WaterShip and Watermaid are trademarks of International Plant Breeding, A.G., Switzerland.