ARE YOU STARVING YOUR AFRICAN VIOLETS?

By Nancy Robitaille

African violets can survive very tough situations. Rooms that are too cold or too hot, insufficient light and even very little food. But for plants that are healthy and vigorous the following things are necessary—and in the correct forms.

If you are using only one type of fertilizer for extremely long periods, you may be starving your plants.

PRIMARY NUTRIENTS:

All fertilizers carry three numbers on their packaging. These are the PRIMARY NUTRIENTS, those which will carry the plant to its ultimate. These primary nutrients are Nitrogen for green foliage, Phosphorus for healthy roots and bud count and Potassium for the general health of the plants.

SECONDARY NUTRIENTS:

Each fertilizer container will have some of the SECONDARY NUTRIENTS which are very important to the development of your plant, as well. Different fertilizers hold varying amounts of secondary nutrients and trace elements. Secondary Nutrients are Calcium, Magnesium, and Sulfer.

CALCIUM: (Ca)—Calcium cements the plant’s cells to one another. Roots must have a good supply of calcium. Calcium neutralizes organic acids in plants and protects plants by acting as a buffer against stress caused by soil toxicity or extremes of acidity or alkalinity. Calcium also makes nutrients available to the plant for higher energy. Calcium influences intake of other plant food. 

Calcium materials are: 
1. Limestone 
2. Caustic lime 
3. Oyster shells, ground finely. 

Deficiency symptoms are: 
1. Leaf tips curl backward 
2. Buds are small, shrivel and die 
3. Tips of leaves brown and curl 
4. Roots turn dark and die.

MAGNESIUM: (Mo)—Magnesium can also be obtained by using Epsom salts. Magnesium is the center core of the chlorophyll molecule in plant tissue. When deficient in magnesium, a shortage of chlorophyll results and plants becoming stunted and are poor in health.

SULFER: (S)—Sulfer releases larger amounts of energy to the plant. It also ensures maximum seed development.

Sulfer gives increased root growth. It helps maintain dark green color and encourages vigorous plant growth.

Sulfer corrects the alkalinity of soil. Sulfer is washed down from the atmosphere and large amounts of this element are furnished by humus and other organic matter in soil.

TRACE NUTRIENTS:

Other elements of fertilizers are TRACE NUTRIENTS which include:

IRON: (Fe)—Even though iron is often found in large quantities in most soil mixtures, the form that it takes does not allow plant roots to use it. This plant food works closely in association with nitrogen and sulfer and helps it to form chlorophyll molecules. 

Iron is available as Ferric Sulphate and Iron chelate.

Iron is used in the correction of iron chlorosis or yellowing of leaves. Acid loving plants like iron which aids in chlorophyll formation. 

Lack of chlorophyll prevents the manufacture of starch needed for energy and growth. Sources of iron: Iron sulfate which is usually present in all soil, but locked up too high a pH caused by over-liming.

Deficiency in Iron shows up in young plant growth first. The blade of the leaf turns yellow while the large veins remain green.


BORON: (B)—African violets need only a very small quantity of boron. An ideal amount of boron would be 6-8 parts per million. Boron helps roots in the uptake of water. Boron also assists the plant’s defense mechanism prevents a large amount of absorbed water from evaporating and escaping from the plant back into the atmosphere.

Borax was one of the first chemicals to be used as a fertilizer, and is used in very small amounts. If one or two parts per million parts of soil is lacking, there may be deficiency symptoms. Borax in too heavy concentration may be toxic.

Boron affects 15 functions of plant growth. The source of borax is borate which is released by the addition of organic matter when it is locked up by improper pH.

Deficiency shows up in form of:
1. Leaf stems being brittle 
2. Base of leaf is yellow 
3. Centers are small and die 
4. Dark spots on tips of young leaves.

MANGANESE: (Mn)—Very small amounts of Manganese will allow it to perform its three functions in a plant. Manganese aids in the formation of the chlorophyll molecule. It makes other plant foods more accessible to the plant and it causes germination to occur more quickly when propagating African violets from seed.

Manganese increases availability of calcium, magnesium and phosphorous. It is vital in chlorophyll formation. If missing, sugar and starch formation is severely checked. 

Too much lime is often the cause of shortage of manganese as this element becomes insoluble in alkaline soils. 

Deficiency shows the color of foliage altered in some way. You can suspect lack of manganese when the veins of the leaf remain dark green, but spaces between veins turn yellow or brown. The deficiency of manganese is different from that of iron or magnesium in that the yellowing takes place in the center of the leaf.

Copper: (Cu) Copper’s role in plants is played in a way that chlorophyll molecules react when light strikes them. Copper is also an energizer since it activates enzymes for starting several important plant processes which produce healthy plants.

Copper is both a poison and a nutrient. It was one of the earlier weed killers in the form of copper sulfate and was not proved to be a nutrient until 1927.

Deficiency shows up in retarded growth. Leaves and stems are flabby. Leaves have a bleached appearance.

ZINC: (Zn) Zinc provides proper growth and function of plants. The lack of this plant food causes yellowing or chlorosis of leaves. Zinc is essential for plant growth and it controls the synthesis of indoleacetic acid which regulates plant growth.

Zinc is also active in many enzymatic reactions and is necessary for chlorophyll synthesis and carbohydrate formation. Deficiencies first appear on younger leaves. 

Plants contain and need as little as one part per million parts of soil. This is a growth regulator and important in the production of protein.

Source of zink is zinc sulfate.

A deficiency is detected by leaves twisting and growing crooked. Color is blotchy. Deficiency is least where organic matter is in abundance. If zinc is lacking the plant will rob older foliage. When enough has been taken, a near normal plant will set on stunted growth.


MOLYBDENUM: (Mo) Like Zinc, an activating compound which causes certain plant-growing processes to occur. Molybdenum is from a Greek word “molybdos” meaning lead.

Molybdenum is a trace element for virtually all life forms. It functions as a co-factor for a number of enzymes that catalyze important chemical transformations in the global carbon, nitrogen and sulfer cycles. Thus, molybdenum-dependant enzymes are not only required for the health of plants and people, but for the health of its ecosystems as well. The biological form of molybdenum is present in almost all molybdenum-containing enzymes and an organic molecule known as the molybdenum co-factor.

Molybdenum is a metallic substance and helps bacteria get nitrogen from the air. As a source it is released by adding lime. It is needed in barely detectable amounts, one part ot one million parts of soil, but the lack of this tiny particle is critical. The amount of molybdenum in soil is always small and the deficience appears when pH is below 5.2

Deficiency would be detected by the same symptoms as lack of nitrogen.

WATER: Water is two parts hydrogen and one part oxygen. Water is a basic food and essential to life of all living things.

CARBON: Carbon in soil contains about six or seven times as much carbon dioxide if the soil contains any amount of organic matter. It is slightly poorer in oxygen due to the constant absorption of oxygen by roots leaving carbon dioxide behind.

CHLORINE: (Cl) Its presence is necessary for the growth of plants. Chlorine is required for certain photo-chemical reactions in photosynthesis. Chlorine uptake affects the degree of hydration of plant cells and balances the charge of positive ions. Deficiency causes wilt.

These trace elements, along with the three major elements are the 15 components of fertilizers. When your plant is lacking in any particular element, you now know how to diagnose the problem and what to do about it. 

By knowing your fertilizers and what they contain as well as what is in your soil, you are equipped to intelligently feed your plants.

When buying fertilizers buy nutrients, not only the fertilizer. Study the label and know what is included. Elements other than the top three nitrogen, phosphorus and potassium are very important.