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This can be as source of much confusion for the novice but the principle is really quite simple. There are three ways to apply fertilizer: by placing pellets on or in the soil, by watering it onto the soil and by spraying it on the leaves (foliar feeding). Each has its own pros and cons and the choice is really based on your own preference.

Specialist bonsai fertilizer pellets are available from all nurseries. They can be either the organic variety such as rape seed cake, or inorganic. The inorganic pellets are coated in a porous membrane which allows the nutrient to pass by the process of osmosis. Both types release nutrients slowly, which means that you don’t have to worry about feeding for a while. The disadvantage is that you won’t be able to adjust the feeding pattern without risking over feeding, which may ‘burn’ the roots.

There are a large number of soluble fertilizers available in. garden centers and florists, most of which are suitable. (Avoid using any specifically intended for house plants as they tend to he too rich for trees). These can be routinely applied once a week or, better still, at quarter strength with every watering. Never use a stronger solution than the manufacturers’ state. If is a good idea to change brand every now and then, in order to maintain a balanced diet. The disadvantage here is that the nutrients wash out of the soil quickly, so you have to be quite strict in your feeding regime. Also, during prolonged spells of very wet weather you may not be able to feed your trees since they may not need any water.

Research has shown that a plant can absorb more nutrients through its leaves than through its roots. Many standard soluble fertilizers can he applied in this way as well as via the soil, while some are specifically designed to be applied in this manner. This technique is particularly useful when your bonsai has root problems or when the soil is constantly wet through heavy rain. Foliar feeds are easy to apply provided you don’t do so in strong sun, otherwise the leaves may scorch. The only disadvantage is that in warm, windy weather the solution dries on the leaves too quickly and leaves a powdery deposit which. is difficult to wash off.

Any of these methods of feeding are suitable for keeping an established tree in good health and vigor, but occasionally you may need to use a specialist feed in order to encourage the tree to perform in a specific way. Before you attempt this you will need to understand a little more about how each of the major nutrients affects the tree.

Phosphorus is primarily responsible for root growth. It also encourages thick, sturdy trunks, helps to strengthen the plant against disease and frosts, and promotes hack-budding. An excess may result in poor foliage growth and color.

Potassium, or potash, is responsible for encouraging flowers and fruit as well as hardening off late growth before the winter. If left out of its diet, a plant will fail to flower, or if it does then the blooms will be of poor quality and the fruit will nor set. Potassium also helps to build up the plant’s resistance to disease.

It is easy to deduce each clement that you use to produce specific results by increasing its proportion in the fertilizer. Here are some pointers as to why and when this should he done.

Nitrogen (N) should be increased when you want a plant to put on a spurt of rapid growth. This applies to young, developing plants which you want to grow larger before starting to train. If the foliage is dull (not yellow - which indicates a root problem) a little extra nitrogen may improve the color.

A high nitrogen feed should be applied as the tree needs it, not before. So in spring, after growth has started, or once new leaves have emerged following leaf pruning, an application of a high nitrogen feed will replenish the tree’s resources.

Phosphorus (P) is especially useful after repotting or when a tree is recovering from a root problem, so a little extra can be given at such times. In fact, a high phosphorus and potassium feed will aid recovery from many ailments.

Increasing the phosphorus content in the diet in late summer and autumn toughens up the tree in readiness for autumn. A pinch of powdered superphosphate on the surface of the soil is an easy method of application.

Potassium (K) should he increased for all flowering and fruiting bonsai. A diluted rose or tomato feed is ideal, as these are specifically formulated to increase the flowering and fruiting potential. Potash can also be increased to help weak plants regain strength.

Extra potassium given during late summer and autumn will help the tree combat the perils of winter. A little sulphate of potash sprinkled on the soil once a week will do the trick.

Some nurseries sell a specialist soluble fertilizer called ‘0-10-10′ which, as the name implies, is nitrogen free and is ideal for late season feeding. When buying fertilizers, make sure that they include trace elements.