Feeding Bonsai Trees

Only trees that have healthy, established root systems should be fed. For freshly repotted trees, commence fertilising using weak liquid feeds, at least one month after root pruning has been undertaken. When repotting trees, it is a good idea to add a small amount of slow release fertiliser granules to the soil mix. These will activate and provide a basic feed as the soil temperature rises, although supplementing with other feeds may be required later. Fertilisers contain three main elements - N.P.K. - nitrogen (for foliage), phosphorus (for roots) and potassium (for flowers). Therefore a fertiliser with an N.P.K. ratio of 10:5:5 has a high nitrogen content and will promote strong growth. To encourage flowering use feeds high in potash, such as bone meal, which can be sprinkled on the soil in the autumn. To harden off new growth for the winter, reduce the nitrogen content towards the end of the summer, switching to a feed such as tomato fertiliser and then to a specialist bonsai fertiliser with N.P.K. ratio of 0:10:10, containing no nitrogen.

Growing in such a small amount of soil, it is easy for a bonsai tree to become deficient when not fertilised adequately. Despite popular belief, bonsai are certainly not starved to keep them dwarfed! When to feed, what kind of fertiliser and how much all depend on the growth that is required. A young tree may need heavy feeding so that it grows vigorously and therefore a fertiliser with a high nitrogen content should be selected. However, a mature, well developed deciduous bonsai should be fed sparingly so that the fine tracery of twigs does not become thick and clumsy. You can control exactly how your tree grows by correct feeding.