Food for ThoughtAboutFood for GrowthBernard D. GreesonMay/June 1964, Gesneriad Saintpaulia News, pgs. 24-26
Are you confused, when you look at the label on a package of commercial fertilizer or plant food for Saintpaulias or other house plants? Usually, you will see the names of certain plant nutrients such as nitrogen, phosphorus, and potash. Or there will be something about trace elements. And as a rule nutrients will be listed by percentage, or numbers will be present like "15-30-15," "20-20- 20," or "12-31-14." Or it may be that there are terms such as "chelate concentrate" or "inert ingredients" or perhaps even more complicated terms.
You may say to yourself: "What does it all mean?" Or you may shrug your shoulders and say: "I don't really care what it means what I want to know is: will it really make my plants grow better and bloom profusely."
The answer to the latter question can probably be given in the affirmative for almost any plant food. For if given the proper growing conditions the right amount of humidity, correct temperature, adequate moisture, sufficient light, a well-balanced soil mix, along with regular feedings most plants adequately protected from disease and insects, will respond favorably and bloom.
Too often, most of us tend to garden indoors and out-of-doors, "by guess and by golly." We often fail to read labels carefully. We know too little about the food needs of the plants we are trying to grow. We wonder what happened to the plant that fails and we rarely really know why a plant did so well that it won a blue ribbon for us. Yet, the answers are usually very simple. But for a myriad of reasons the question: "What does it all mean?" very often does not get answered.
Some growers, it seems, always seem to have "good luck" and carry off ribbons galore, everytime the local society has a show. We look with some envy, perhaps, on these "lucky" growers and decide that they must possess some mysterious power, commonly known as a "green thumb."
But successful growing is not a mystery. The proverbial "green thumb" is not a mysterious gift given to some and not to others. Successful growing comes from bothering to find out "what it all means." Successful growing is a science. It involves being scientific in our approach to growing problems. All we really need to remember is that there is a reason for everything. Usually the reason is a very simple one.
Not long ago a letter came to my desk bearing this interesting statement on the envelope: "YOU NEVER OUTGROW THE NEED TO KNOW." With this as our text, I hasten to write some things you may already know and perhaps some about which you do not know.
It used to be, when I was a kid, that when we wanted to fertilize the garden and the lawn, we bought a load of farm manure and spread it over the garden or lawn in the fall or early spring. Today, as we become more and more urbanized, it is almost impossible in many areas to buy a load of natural fertilizer. Actually, we are probably better off because animal manures are often poorly balanced.
So, today, garden centers, hardware stores florists, dime stores, and many other places of business sell many different brands of fertilizers and plant foods packaged in many different quantities. Today, you can buy a specially compounded plant food for almost any plant you want to grow. But with so many on the market, it is confusing and sometimes difficult to know which one to buy. But it helps, if you can understand the label.
To dispel some of this confusion, let us begin by making a few important definitions.
In the first place, what is a fertilizer? It is a plant food and if it is a complete food, it contains a certain percentage of plant nutrients, nitrogen, phosphorus, and potash.
These are the major elements required by all plants for
growth, maturation and flowering or bearing of fruit. They are absolutely essential to all plant life. Let there be a deficiency of any one of these life-giving elements, and the plant begins to show signs of starvation.
Secondary elements of nutrition include calcium, sulphur, and magnesium. These are usually supplied by the same fertilizers which supply the major nutrients and they are also supplied when lime is added to the soil.
Minor elements, commonly referred to as "trace elements," and highly essential to the plant, include such elements as iron, copper, zinc, manganese, boron, molybdenum, and magnesium. I believe it would be correct to say that these minor elements very often account for above average performance in a plant. Let us say that it is like adding frosting to a cake. The cake is good without it but better with it. Yet, a plant will show need for these elements by dropping its blossoms, by yellowing leaves, bud drop, and other such symptoms. But it should be added that these signs also may be an indication of disease, other hungers, too little or not enough light, etc. Like the medical doctor, a grower must often diagnose plant troubles from symptoms which result from a number of causes.
Minor elements or "trace elements" are supplied in rather generous amounts by leaf mold. They are present in varying amounts in many commercial fertilizers and in special commercial compounds such as "Tem," "Tru-Green Organic Chelates," and other such products.
The term "Chelates" (pronounced key-lates) refer to nontoxic (nonpoisonous), odorless plant food elements in dry powdered form. They are treated to keep them from dissipating from the soil with successive waterings. They are treated so that they are available as mineral salts which can pass through the roots easily and into the plant's circulatory system. Trace elements may be present in soils but they may be "locked in" or in such form that the plant can not use them. Chelatation processes protect these elements from, soil lock-up, that is, combining with other elements in the soil to form insoluble compounds which become unavailable to plants. The J. J. Mauget Company, 4151 E. Olympic Blvd., Los Angeles, California, has a very informative leaflet entitled, "Plant Hunger Chart," which I am sure you would find helpful. It tells about chelates and has a very informative chart about the characteristic symptoms of trace mineral, secondary, and major nutrient hunger signs in plants.
Nitrogen is essential to plant life because it gives the rich green color to the plant and promotes growth. It is essential to the growth of leaf, stem, fruit and seed. It is rapidly exhausted from the soil by growth processes and by leaching out (washing out).
This means that especially where plants are grown in pots, the supply of nitrogen must be replenished often. But here is probably a good place to add a word of caution. Too much of an element may be harmful to a plant. So it is best to space fertilization at regular intervals and to be careful not to overfeed. The best way to be sure is to READ the LABEL and follow the manufacturer's directions in the use of the plant food. The pitfall many growers fall into is in thinking, that since a little is good, more will be better. This is rarely the case. You cannot play games with commercial fertilizers or any plant food for that matter. Follow the directions!
There are two kinds of nitrogen, organic and inorganic. Organic nitrogen is in a form which cannot be used immediately by the plant. It must be changed by bacteria in the soil to a chemical or inorganic form before it can be absorbed into the plant system. But organic nitrogen is not so easily leached out of the soil either. And that is why soil containing organic matter such as fishmeal, blood meal, hoofmeal, bonemeal or various manures may support plant life for a longer time without additional fertilization. The bacterial action is quite slow but it may be speeded up with certain products now on the market which inoculate the soil with minions of bacteria. These bacteria condition and activate the soil, thus speeding up the release of soil nutrients.
Organic nitrogen, then, will feed much longer, but takes longer to become available. Some fertilizers contain both organic and inorganic nitrogen. Inorganic nitrogen is chemical nitrogen which has been released when dissolved in water, it is taken into the plant immediately.
Some labels on fertilizer packages tell you how much organic and inorganic nitrogen is available, but many do not. This does not mean, however, that the latter do not contain organic and inorganic nitrogen. It would be helpful, though, if all manufacturers would be more specific in their labeling. This is a problem to the consumer in buying other products such as in a food market. There is a great need for more accurate and more specific information on labels, and we might add more uniformity.
Phosphorus another vital major nutrient stimulates flowering. It is vital to root crops and crops bearing fruit. It is also vital to vigorous root development and growth. Without phosphorus there could be no life, for it is intimately associated with all life processes and every living cell, It too can be provided by some organic materials such as bonemeal Bat Guano and other manures, cottonseed meal, soy bean meal, etc. it is also provided by such inorganic materials as rock phosphate which is at least 30% P2O5. (phosphoric acid).
Potash is essential to plant life in the building of resistance to disease and in producing hardiness in petioles or stems. It also helps to give the plant vigor and keeps the plant's vascular system or circulatory system open. It Is present In varying amounts in manures, hardwood ashes, etc. It is present in large amounts in Glauconite or Greensand as well as in Hybro-Tite.
A balanced fertilizer is one which has been compounded in certain proportions to meet the requirements of certain plants. It has a formula which indicates what is in it and how much. This formula is called a ratio, that is there is a certain relationship between the elements included in the plant food. For instance there may be twice as much phosphorus in the formulation as there is nitrogen and potash. Such a ratio might be 15-30-15. This means that there are 15 measures or units of nitrogen 30 units of phosphorus and 15 units of potash. These ratios are always stated in this order nitrogen phosphorus, and potash. Thus, the first number always indicates the amount of nitrogen, the second or middle number, phosphorus, and the last number, potash.
There are many ratios. A 1:1:1 ratio means equal parts of the three elements. For example: 10-10-10 or 20-20-20 The only difference in these two is in the degree of concentration. While the two have equal parts of the three nutrients, the 10-10-10 is half as strong or concentrated as the 20-20-20. A 2:1 ratio means as we said before that there is twice as much phosphorus in the plant food as of nitrogen and potash but a 15-30-15 fertilizer is more concentrated than a 5-10-5.
African violet plant foods have many different formulas. The most standard seems to be 15-30-15. But to give you an idea of the many different ones, here are a few taken from very popular violet foods: 23-21-17 7-6-19, 12-31-14, 4-10-10, 10-52-17, etc.
A recent formulation is a 10-30-20 fertilizer geared for variegated foliage in violets. Here nitrogen is withheld to promote more variegation in the foliage.
We have already mentioned a free leaflet that tells about some of the signs or symptoms of nutrient hunger. Many violet books give these signs in quite some detail. The only trouble with these signs, if we may be permitted the luxury of repeating, is that they are not always conclusive since they may indicate other trouble too. In general, however, we suspect nitrogen deficiency when leaves turn yellow and growth is dwarfed or slow. We can blame poor bloom or no bloom on a deficiency of phosphorus. And lack of potash is sometimes indicated by weak stems curling of leaves, firing starting at the tip of the leaves and proceeding downward, shriveled blossoms, etc.
Since symptoms are not entirely reliable, there is only one sure way to know. That is to test the soil. There are chemical tests which can be applied to samples of soil that will tell the story. One way is to take a sample to your county agricultural agent and ask him to test your soil. As a result of the tests he can tell you what your soil may be lacking and he can also tell you whether your soil is too acid (sour) or too sweet (alkaline).
Another way is to invest in a soil test kit. Sudbury Soil Test Kits are advertised in almost every garden magazine. They are available in numerous sizes all the way from a very small inexpensive kit to a super deluxe horticultural kit. They are not complicated to use and do not require a knowledge of chemistry. I would recommend the kit (Model-D) which is quite adequate for growers of Saintpaulias, Gesneriads, and other houseplants.
In a future issue of GSN, we will discuss soil acidity and alkalinity or pH and what it means. In this same article we will discuss in greater detail how to test soil for soil nutrients and pH.
Like animals, all plants require food to grow and bloom. To have a "green thumb," we need to know what food is required and grow by the scientific method, not by guess.
(Modern day note: check out AVSA's FAQ page for diagnosis information.)