Summary: A complete fertilizer or plant food – organic or inorganic – is one very key “item” for success in the lawn, with landscape plants, in your garden and with your houseplants. With a little study of fertilizers and their recommended uses, you can save money and increase productivity.
Question: The garden center recommended a “complete fertilizer” to use on the lawn, landscape trees and shrubs for my yard, how do I go about choosing the right fertilizer for my use? Martin, Peachtree, Georgia
Answer: Martin, homeowners face many options in choosing from a great variety of fertilizers on the market today, and may at times be uncertain which one to select for their particular needs.
There are organic and inorganic fertilizers, both of which are available in powdered, granular, and liquid forms.
Then, some are complete, or balanced; others are prepared for special purposes. A study of fertilizers and their recommended uses is well worth while, both in terms of money saved and in increased productivity.
What Are The Essential Elements of Complete Fertilizer?
All balanced fertilizers must contain three basic elements:
- (1) Nitrogen, which promotes leaf and stem growth
- (2) Phosphorus, which helps plants grow and flower as well as makes their stems strong
- (3) Potash, which aids root growth and, to a certain extent, acts as a balance wheel between the other two.
By law, the percentage of these three fertilizer elements making up the “plant food” must be printed on the bag or container.
The percentage, or number of pounds of each element per 100 pounds, is expressed in numbers such as:
… and so forth, and always in the same order: nitrogen, phosphorus, potash.
If the total amount of each element in a particular fertilizer is not in a form which plants can use as plant food, the analysis must also show the percentage which is available to plants.
Many fertilizers also contain some:
… etc., which may or may not be listed.
What Are The Basic Types Of Plant Food Fertilizer?
There are several ways to classify fertilizers, but first we shall divide them according to whether they are organic or inorganic.
Organic fertilizers are those derived from animals or from plants. These include:
- Sewage sludges (Milorganite)
- Cottonseed meal
- Dried blood
- Manure (fresh or dried)
- and others
These materials are comparatively low in their chemical analysis but they often appear to furnish benefits out of proportion to their content.
They cannot burn your plants and they release their chemicals slowly as they gradually decay.
Natural Chemicals In Fertilizer
The inorganic fertilizers are already in their basic chemical form. A number of them, like some limes and rock phosphates, are natural chemicals.
Others are manufactured chemicals. Since they are already in chemical form—which is the only way in which the plants can absorb them regardless of their origin – they take effect much faster than organic fertilizers. Decay is not necessary.
Other points in their favor are that they are usually cheaper, you can control more accurately the amount of plant foods you provide.
They also have higher concentrations of plant fertilizers so that you need less inorganic than organic fertilizer to do the same job.
What Is Synthetic Fertilizer? = Man-Made Chemicals
To confuse us, however, science has now given us synthetic organics, man-made “natural foods.”
These fertilizers are members of the urea-form group, relatives of the plastics, and release their one plant food, nitrogen, slowly as they decay.
In the North they may release it over the entire growing season; in the South they break down more quickly.
Although they are highly concentrated – containing up to 40 per cent, or more – they cannot burn roots or leaves. Nitroform has been a widely advertised brand.
A third basic group is the liquid fertilizers. Here we include both types, the organic liquid fertilizers such as the liquid fish emulsions and the purely chemical, or inorganic, soluble powders and liquids.
Both are convenient to use and equally effective in the soil. The inorganic group, however, lends itself to somewhat more rapid absorption when used for foliar or on-the-leaf feeding.
They usually come in more highly concentrated form and a little goes a long way. But, by the same token, they must be used with greater care and strict adherence to the manufacturer’s instructions.
Read More On: How To Use Plant Fertilizer Concentrates
Finally, we have the specialized fertilizer such as lime-free azalea, camellia, and holly fertilizers, rose or bulb foods, African-violet foods, etc.
Their uses are indicated by their names. In this category, too, are the common gypsum, used in limestone sections to supply calcium without increasing alkalinity, and sulfur, used as a minor plant food and soil acidifier.
Fertilizer By Content Type
We can also divide fertilizers into two groups according to their contents. One is the high-nitrogen fertilizer type, which promotes leafy growth on lawns, leaf vegetables, and foliage plants – this is why you should Know Your Fertilizer.
A good example of this is 10-5-5, used on lawns in some areas. The other is the low-nitrogen type, in which phosphorus and potash play a more important part.
One of these is 5-10-10, used primarily as a tree, rose, and bulb food. Use the first type where stem and leaf growth is wanted and the second where flowers and fruits are important, as well as for all root crops.
Read More On: Applying Fertilizer… How Much
Hopefully you now have a better idea of the fertilizer you need for the job and can now buy the “complete fertilizer” needed to do the job.