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.

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.

The 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.

Examples of organic fertilisers: blood and bone and sheep pellets

Inorganic

Inorganic (or complete) fertilisers are manufactured 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.

Examples of inorganic fertilisers:

• Granular forms like General Fertiliser and Lawn Fertiliser
• Compound forms like Tui Novatec
• Soluble forms like Tui Eco-Fert and Seasol

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

Choosing what you need

• For general garden fertilising and soil conditioning use Tui Blood & Bone, Tui Lime, Tui Pea Straw or Tui Super Sheep Pellets.
• To make specific blends choose from the Tui Tech Range of Superphosphate, Sulphate of Ammonia and Sulphate of Potash.
• For particular groups of plants like bulbs, roses, potatoes and fruit choose from the Tui Food Range. The product name makes it obvious what it is to be used for e.g. Tui Potato Food.
• To solve specific garden problems choose from the Tui Garden Remedies Range; these Tui remedies are like the first aid kit for your garden.

There are 3 major nutrients in fertilisers and each plant likes these main ingredients in different amounts. This are represented as an NPK value on inorganic fertiliser packaging.
It’s the quantities & ratios of these elements that make the difference, but there are plenty of other goodies in the bag specifically designed for each plant.

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.