Bonsai care (mulberry)
Placement
Mulberry is not a houseplant, so it should spend most of the year outdoors. It is a light-loving plant. Keep it in a bright spot, but in summer shield it from the scorching midday sun. From June through August you can keep it indoors, in a well-lit place. From September, though, be sure to move it back outside.
Watering
A bonsai needs regular, careful watering. In nature, a plant’s roots grow deep into the ground. If it happens not to rain for some time, the plant can still get the water and nutrients it needs thanks to its deep roots. Confined to a container, a bonsai has no way to steer its root growth wherever it is needed. There is very little soil in a pot, so a bonsai depends far more on watering than a tree growing in nature.
It is also worth noting that on hot summer days, the movement of water through the plant and its evaporation from the leaves regulates the plant’s temperature and protects it from overheating. As long as the soil is moist, the plant can keep developing normally even in very high temperatures. When water is lacking, however, “burn” spots appear on the leaves and shoots, which ultimately causes the plant to dry out and die.
How much and how often to water
How often a bonsai needs watering depends on the conditions around it, the soil in the pot and the species itself. A bonsai should be watered not on a strict schedule, but as needed. In late spring and summer, for example, watering once a day may not be enough. There is another misconception: that watering while direct sunlight is falling on the plant harms it. In summer it is sometimes even essential to water a bonsai during the sunny part of the day. So don’t draw up a schedule along the lines of: “The bonsai must be watered once a day, in the evening.”
Some species need their soil to stay constantly moist, others need less moisture, but letting the soil dry out completely for a day or two very often kills the plant. Be sure to check the condition of the soil every day and water whenever it is needed.
There are a few simple signs that tell you the soil is drying out: as the soil begins to dry, its surface changes color; the surface of dry soil is relatively hard; and if the bonsai has been in its pot for a few months, you can also judge whether it needs water by picking it up. The difference in weight is quite noticeable — dry soil is markedly lighter. On deciduous trees, the first sign of late watering is drooping leaves and new shoots. Bonsai are watered with a special small watering can that lets the water flow out slowly. Pouring a large amount of water all at once washes away the soil surface and leaves hollows here and there.
Use ordinary tap water for watering. The drawback of such water is its chlorine and high salt content. After regular watering with it, the surface roots and the rim of the pot become covered with a white deposit. You will need to remove this deposit from time to time.
Make sure that water runs out of the drainage holes after watering; otherwise only the surface may get wet while the soil deeper down stays dry. It often happens that a bonsai is planted in its pot in such a way that much of the water you pour runs off the surface and over the side of the pot. In that case, pour the water slowly, only as much as will not overflow the surface, wait for it to soak in, and add more, until you are sure the soil in the pot is wet all the way through. The sign of thoroughly moistened soil is water running out of the drainage hole.
Suppose the soil in the pot has dried out completely. If you look closely at the pot in such a case, you will see that a gap has formed between the pot and the soil. If we water in this state, much of the water will run through the gap and straight out of the drainage hole.
In this case it is better to stand the plant in a vessel larger than the pot, fill it with water up to the rim of the pot, and lift it out once the soil surface is wet. The excess water will drain out of the drainage holes. In spring and summer a plant needs more water than in late autumn or winter. In winter you may find that you water the plant only once a month throughout the whole season (do not water a bonsai during frosts).
The time of day you water a bonsai also matters. In late spring and summer, when temperatures are high, it is best to water so that the soil in the pot stays moist through the night. Water in the evening, after sunset. If you water only in the morning or at midday, the soil will soon dry out and the plant will in effect spend the whole night in dry soil. In autumn, when the sun is no longer so fierce, you can water a bonsai at any time of day, preferably in the morning.
As for overwatering: when the soil around the roots is constantly wet, the amount of oxygen in the soil drops, which then damages the fine roots. The damaged roots begin to rot, and if the process is not stopped, a large part of the root system will gradually rot away. As a result, the tree first weakens and, if the situation is not corrected, dies. So once you have watered a bonsai thoroughly, let the soil dry out gradually, and only then water again.
Overly wet soil in a pot can also be caused by persistent rain. But even a week of nonstop rain will do the plant no harm. The danger is when the soil in the pot stays waterlogged constantly, throughout the whole season.
Bonsai care in winter
In winter trees are dormant, and their active growth is suspended until spring. Dormancy is just as essential to a plant’s vitality as the period of active growth. That is why bringing a bonsai into the warmth in winter merely because it “might catch cold” is fatal to the plant. Of course, bringing it into a room for a day or two to decorate the interior will do no harm. But if it stays in the warmth all winter, it will certainly die.
In temperate regions where winters are not too harsh, a bonsai does not need any special conditions to overwinter. But in regions where winter temperatures are regularly low (-5°C and below), the plant must be protected from frost. This applies above all to the roots. Bonsai roots are not buried deep in the ground and can therefore freeze easily. In Tbilisi’s climate the risk of freezing is lower. But if hard frosts go on for a long time, take a vessel much larger than the pot and bury the plant, pot and all, in sand or sawdust. Under these conditions the plant’s roots are relatively well protected from frost.
Protecting bonsai in summer
At temperatures above 30°C, unless special measures are taken to protect a bonsai, the plant may be damaged or even die. How well a plant withstands abnormally high heat depends on its own heat tolerance and on how many hours a day the high temperature lasts.
The effect of heat is easy to see on a deciduous tree. A plant cools itself through its leaves, by evaporating water. In high temperatures a plant quickly loses moisture. When a bonsai gets too little water in the heat, the leaf temperature can reach a critical point. Wilting leaves are the first symptom of a lack of water. In extreme heat a plant may go dormant prematurely (as it does in autumn). The leaves change color and drop — first the inner and lower leaves of the canopy, then the rest. When direct sunlight falls on a bonsai, the soil in the pot also heats up considerably. High temperatures can damage the roots too. Under such conditions the plant becomes less resistant to diseases and pests. On conifers, however, these processes are hard to spot, because the needles do not give such “signals”. That is exactly why conifers need special attention in summer. A plant can cope quite well with very high temperatures if you give it normal conditions to function. There are a few simple ways to protect a bonsai from extreme heat. Keep it out of direct midday sun, or rig up some kind of shade. Do not stand a bonsai on a surface that gets very hot in the sun: stone, concrete, metal. Try to raise the humidity around the bonsai: mist it more often and wet down the area around it. Make sure the soil in the pot never dries out completely. Watering at midday is another way to cool the roots.
Fertilizer
For normal growth and development, besides the carbon (C), hydrogen (H) and oxygen (O) that a plant takes from air and water, a plant must obtain macro- and micronutrients from the soil. The macronutrients are nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). Various micronutrients are also needed in very small doses: iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), boron (B), manganese (Mn), sodium (Na) and other elements. All of these elements are vital to the plant’s existence, the macronutrients above all. An excess or deficiency of any one of them has a marked effect on the plant’s development. For example, nitrogen is needed to regulate growth, for the leaves and for fruiting. A nitrogen deficiency soon shows itself as slowed growth; an excess prolongs the growth of new shoots. Nitrogen-rich fertilizer is not applied in the second half of the growing season. Phosphorus promotes the plant’s development and root growth, and strengthens its tolerance of drought and frost. Potassium makes the plant resistant to stress (very high or low temperatures, too much or too little moisture). The optimal amount of potassium improves the buds’ ability to survive winter and the plant’s resistance to fungal and bacterial diseases. Calcium is essential for normal metabolism in the plant. Because there is so little soil in a pot, nutrients are soon exhausted. That is why regularly applying a fertilizer that contains all these elements is just as essential as watering. Without extra feeding a plant develops poorly, its leaves and needles lose their color, and it falls prey to disease more easily.
For bonsai you can use either organic or mineral fertilizer, but you must not mix them together and apply them that way. There are fertilizers made specially for bonsai that contain all the necessary elements. They can be either liquid or solid, in granular form. Liquid fertilizer is dissolved in water at a given dose and the plant is watered with the resulting solution as usual. Plants take up liquid fertilizer fairly quickly, so on conifers it is applied once every 3 weeks. Granular fertilizer acts over a longer period. It is either mixed into the soil or placed in special small baskets set on top of the soil. With each watering a certain amount dissolves and gradually feeds the bonsai. You can order special bonsai fertilizer online. If you can’t find such a fertilizer, you can use a compound fertilizer sold in garden centers or flower shops. As a rule, these contain all the elements plants need. For bonsai it is best to use one that dissolves well in water; such fertilizers are more convenient to use. The packaging always lists the composition in percentages (NPK) and how much water to dissolve it in. Take great care when fertilizing and work out the right dose carefully, because too much can kill the plant. Ideally it should be NPK 10-10-10 and contain micronutrients. Normally, feeding begins in early spring and ends in autumn. There is no need to fertilize in winter. Never fertilize a freshly repotted plant. Fertilizing is acceptable only 4–5 weeks after the start of the growing season, once the bonsai has rooted well. At Samto Kimia you can buy “Kristalon 20-20-20” fertilizer. Dissolve 2 grams in 1.5 liters of water.
Misting
Misting is essential for both deciduous and coniferous plants. Start misting once warm weather sets in, in spring, and continue until leaf fall begins. In summer it is best to mist every day; naturally, in rainy weather there is no need at all. Mist the bonsai when you water it.
Some water-soluble fertilizers are also intended for foliar spraying. This encourages lush, healthy leaves that do not fall ill so easily. There are also water-soluble foliar feeds whose spraying gives quite good results. If it is needed, spray with dissolved fertilizer or foliar feed once a week, or as often as you feed the soil.
Diseases and pests
Like all plants, bonsai get diseases and are attacked by pests. So it is better to spray preventively once a month from spring to autumn. Dissolve Ridomil Gold, Strobi Star and Actellic together in water at the required doses and spray. Never spray a bonsai in an enclosed space.
