Fertilising Guide

Fertilising replenishes soil with nutrients previously leached or used by plants and provides nature with that helping hand in order for plants to be healthy and vibrant.

Under natural wild conditions plants grow to the extent of the nutrients available. When plants are grown under cultivation, the demand for nutrients is greatly increased because of the permanent loss of nutrients that takes place when the crops are removed.
Healthy plants experience stronger growth, brighter flowers, more abundant fruiting, tastier vegetables and are less susceptible to pests and diseases.

A fertiliser is anything that can be used to supply nutrients to plants and has two main components:

Macro nutrients
These elements include nitrogen, phosphorus, potassium, calcium, magnesium and sulphur and are usually required in relatively large quantities.

Micro nutrients/Trace elements
These elements include iron, chlorine, copper, manganese, zinc, molybdenum and boron and are usually required in minute amounts.
If one is deficient it may cause a severe abnormality in growth (e.g. whiptail in brassica crops is caused by deficiency of molybdenum). If a trace element is present in too high a concentration it may be toxic to the plant or lock up other elements. The correct balance is essential.

There are two broad types of fertiliser:

Organic
Organic (or incomplete) fertilisers are derived from plant and animal remains and are often referred to as manures. Organic manures help to improve the physical condition of the soil by improving the structure, micro-organism activity and the water-holding capacity of soils. The nutrient content can vary considerably according to the age of the manure, the origins of the materials and the conditions under which they are stored. Generally their nutrient value is low. Micro-organisms are required to break the compounds down and make the nutrients available to plants, in cold weather this may be a very slow process. 

Inorganic
Inorganic (or complete) fertilisers are manufactured by people and are usually a more concentrated form of nutrients than organic fertilisers.  For example, 100 grams of a General Garden fertiliser is roughly equivalent to 3kg of organic manure per square metre, in nutrient content.  The nutrients in inorganic fertilisers are readily available to plants as they do not need to be broken down first.

Ideally, a combination of both manures and fertilisers should be used.

What is NPK?
Inorganic fertilisers contain nitrogen (N), phosphorus (P) and potassium (K) - the three major nutrients. These three elements are essential for your plant’s healthy growth. The proportion in which these are present in the fertiliser is usually stated on the outside of the pack as an NPK ratio. Tui General Fertiliser has an NPK ratio of 5-5-5 which means there is 5% of the pure element nitrogen, 5% of the pure element phosphorus and 5% of the pure element potassium.

Organic fertiliser contains only one (or perhaps two) of the major nutrients (e.g. urea which contains 46% nitrogen). In most instances it is safer and more convenient to use a complete balanced fertiliser.  Make sure you follow the application rates and instructions on the bag to get the best results.  Too much of one nutrient can affect the uptake of others or may damage the plant. A plant grows best when all the nutrients it needs are adequately supplied in balance.

N-P-K

• Nitrogen stimulates thick, rich, green growth of plants.
• Phosphorus encourages root development and growth.
• Potassium is responsible for the formation of flower buds and fruit and maintains overall plant health.