All fertilizers contain the same three basic ingredients: nitrogen (N), phosphorous (P) and potassium (K), plus minor trace elements (TE).
All fertilizers list their nitrogen-phosphorous- potassium content somewhere on the container. The percentages of each are indicated by numbers such as 5-8-7, 18-18-18, 12-31-18. Ther first number indicates nitrogen content , the second number phosphorous content and the third number potassium content.
Other elements include magnesium, iron, sulfur and calcium. Trace elements: Although required only in very small amounts, these are vital to the overall health of plant development.
What Nitrogen (N) Does
Nitrogen develops the plantís green colour in the foilage and stems.
What Phosphorus (P) Does
Phosphorus is very important in development flower, seed and fruit production. It also helps in root development and aids the plant in resisting disease.
What Potassium (K) Does
Potassium helps the plant in its overall development - its general health and durability. The stronger the plant, the better able it is to resist disease.
For specific needs, purchase according to the higher percentage readings, such as 12-31-18 for flowering plants; but for general use, any all purpose fertilizer such as 10-5-5 or 7-7-7 is recommended.
Plants that are kept indoors, especially if they are grown in low light, do not require as much fertilizer as those grown outdoors, because they manufacture less starch and sugar. When feeding, be sure to follow the directions on the container, but never feed a plant if the soil is dry.
Fertilizers can be purchased in liquid , powder or tablet form, and can be applied to the soil or leaves. Plants can be foliar fed but this is no substitute for a good soil-applied fertilizer .
Plants that are kept pot-bound must be fertilized regularly because they can no longer receive adequate nutrients from the soil. This is very important if a plant is kept pot -bound. Newly potted plants generally do not need fertilizer for about two months after they have been potted in fresh soil.
It is important that you do not overfeed plants. its always better to underfeed than overfeed, as the oversupply of nutrients will cause a toxic condition in the soil that will harm the roots. Signs of overfeeding are yellowing leaves and browning edges. Flower buds may blast before opening.
Plants should be fed during active growth , but overfeeding during dormancy can be harmful. Cut back feeding at this time since the plants do not use as many nutrients when they are inactive.
Signs of underfeeding are recognizable in the form of yellowing leaves, loss or lower leaves and smaller and less vigorous new growth.
Any symptom should be viewed with overall care in mind. For example, yellowing leaves could be a sign of insufficient light. As suggested before, make a checklist if care before instituting any corrective measures.