A bonsai tree behaves in a pot much as it would in nature. Deciduous trees change colors and drop their leaves, fruiting trees bear fruit and pine trees drop needles. Their requirements don't change as much as you would expect to accommodate the fact that they're living in the confines of a shallow container. The most important factors to consider when caring for bonsai trees are water, light, soil and nutrition. These elements work together to maintain healthy bonsai plants that will flourish from year to year.
- Whereas a tree in nature can spread its roots many feet in every direction to search for water, a bonsai has to have water provided to it on a continuous basis. Shallow bonsai pots can lose moisture rapidly, so consistent, regular watering, sometimes more than once a day in summer, is necessary. Bonsai have different water needs at different times of the year, so observing a plant's habits is important. Test the soil in the pot daily. It should remain moist, but not soggy. Water bonsai either in the morning or evening, possibly both during the hottest part of the year. If possible, avoid using chlorinated water for bonsai trees. Rainwater is an excellent choice and can be trapped in a bucket and used when needed.
- Light is a source of nutrition to all plants, and offering bonsai enough of the right light is as important as providing it with enough watering. Knowing the light needs of a particular plant species will offer invaluable information about how to care for it. Bonsai also needs balanced light to develop evenly. When positioning bonsai, take care to provide them with equalized light or rotate them often to achieve the desired results.
- Beyond water and light, bonsai rely on the right soil to survive. There are many theories on the best soil mixture for bonsai, and different varieties have specific needs that should be considered. The goal of bonsai soil is to be dense enough to retain moisture to feed hungry tree roots while draining fast enough to keep the roots from being harmed by standing water.
- The interaction of water and soil helps deliver nutrients to feed bonsai tree roots. Supplementing this nutrition with fertilizers helps keep bonsai trees in top condition. Although fertilizer can be fed as a liquid, powder, a firm cake or granules, it's important to monitor its absorption to know when additional feedings are needed. This can be done according to a set schedule, or as the result of careful observation of the plant.
Part of caring for a bonsai tree is being observant of any changes in the plant. Small changes can be a signal of problems that need attention. Pests and diseases afflict bonsai as they do other plants in nature. The good news is that bonsai are hardy and can often recover from infestations, but catching them early is important.
When enjoying bonsai, watch for small spots of spit on leaves that signal the presence of the larvae of spittlebugs, or the black or red dots of mites that can appear on tree bark. Both of these can be wiped off or brushed away. More persistent insects like sap-sucking scale insects or aphids that leave sooty or sticky residue can be treated with insecticide. Other insects, like weevils, leaf miners, snails and caterpillars, inflict damage to leaves that will be easy to recognize.
In the next section, we'll talk about pruning and shaping bonsai to expose its beauty.