Bonsai care (hornbeam)
Placement
Hornbeam 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, and 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 tree’s roots grow deep into the ground. If it happens that no rain falls for some time, the plant can still get the water and nutrients it needs thanks to its deep-reaching roots.
Confined to a pot, a bonsai has no way of steering its root growth in the direction it needs. There is very little soil in the pot, so a bonsai depends on watering far more than a tree growing in nature does.
It is also worth noting that on hot summer days, the movement of water through the plant and its evaporation through 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 at very high temperatures. When water runs short, however, “scorch” spots appear on the leaves and shoots, and in the end this 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 it is kept in, the soil in the pot and the species itself. A bonsai should be watered not on a strict schedule but as it needs it. 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 is harmful to 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, while 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 becomes necessary.
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 noticeably harder; and if your bonsai has been in its pot for a few months, you can also tell whether it needs water by picking it up. The difference in weight is quite noticeable — dry soil is much lighter. On deciduous trees, the first sign of late watering is drooping leaves and fresh shoots. For watering bonsai, people use a special small watering can that lets the water flow out slowly. If you pour a large amount of water at once, the soil surface gets washed away and hollows form 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 after watering, water runs out of the drainage holes; otherwise only the surface may get wet while the soil deeper down stays dry. It is common for a bonsai to be 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 won’t overflow the surface, wait for it to soak in, and add more, until you are sure the soil in the pot is thoroughly wet. The sign of well-moistened soil is water flowing out of the drainage hole.
Suppose the soil in the pot has dried out completely. If you look closely at the pot in this situation, you will see a gap has formed between the pot and the soil. If we water it in this state, most of the water will run through the gap and straight out of the drainage hole.
In this case it is better to place the plant in a vessel larger than the pot, fill it with water up to the rim of the pot, and lift the plant out once the soil surface is wet. The excess water will drain from the drainage holes. In spring and summer a plant needs much more water than in late autumn or winter. In winter it may turn out that you water the plant only once a month for the whole season (do not water a bonsai during frosts).
It also matters what time of day you water a bonsai. In late spring and summer, when temperatures are high, try 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 soon dries out and the plant effectively spends the whole night in dry soil. In autumn, when the sun is no longer so fierce, you can water your 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. This in turn damages the fine roots. The damaged roots begin to rot, and if the process isn’t stopped, much of the root system gradually rots away. As a result, the tree first weakens and then, if the situation isn’t corrected, dies. So after watering your bonsai thoroughly, let the soil dry out gradually, and only then water again.
Soil in the pot can also become waterlogged from persistent rain. But even a week of nonstop rain will not harm the plant. The danger is when the soil in the pot stays saturated with water constantly, for the whole season.
Bonsai care in winter
In winter trees are dormant, and their active growth is suspended until spring. The dormant period 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 for the plant. Of course, bringing it indoors for a day or two to decorate the interior will do no harm. But if it spends the whole winter in the warmth, 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 regularly drop low (-5°C and below), the plant must be protected from frost. This applies above all to the roots. A bonsai’s roots are not buried deep in the ground, so they can easily freeze. 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. In these conditions the roots are relatively well protected from frost.
Protecting bonsai in summer
At temperatures above 30°C, unless we take special measures to protect a bonsai, the plant can be damaged or even die. How well a plant copes with abnormally high heat depends on its own heat tolerance and on how many hours of the day the high temperature lasts.
On a deciduous tree the effect of heat is easy to see. A plant cools itself through its leaves, by evaporating water. At high temperatures the plant quickly loses moisture. When a bonsai gets too little water in the heat, the temperature of its leaves can reach a critical point. Wilting leaves are the first symptom of water shortage. In extreme heat the 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 sun falls on a bonsai, the soil in the pot also heats up considerably. High temperatures can damage the roots as well. Under such conditions the plant becomes less resistant to diseases and pests. These processes are hard to notice on a conifer, however, because its needles don’t give such a “signal.” That is exactly why conifers need special attention in summer.
A plant can cope with very high temperatures quite well if you give it normal conditions to function. There are several simple ways to protect a bonsai from extreme heat. Keep it out of direct midday sun, or rig up some kind of shade. Don’t 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, apart from the carbon (C), hydrogen (H) and oxygen (O) that a plant gets from air and water, the 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 a plant’s existence, especially the macronutrients. An excess or shortage 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 up as slowed growth. An excess makes new shoots keep growing longer. 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). An optimal amount of potassium improves the buds’ ability to overwinter 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 quickly used up. That is why regularly adding 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.
You can use either organic or mineral fertilizer on bonsai, but you must not mix the two together and apply them that way. There is fertilizer made specifically for bonsai that contains all the necessary elements. It comes either as a liquid or as solid granules. Liquid fertilizer is dissolved in water at a given dose and the plant is watered with the solution in the usual way. Plants absorb liquid fertilizer quite quickly, so on conifers it is applied once every 3 weeks. Granular fertilizer works over a longer period. It is either mixed into the soil or put into special small baskets placed on top of the soil. With every watering some of it 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 balanced compound fertilizer sold in garden centers or flower shops. As a rule, these contain all the elements plants need. For bonsai it’s best to choose one that dissolves well in water, as it is more convenient to use. The packaging always lists the composition in percentages (NPK) and how much water to dissolve it in. Be very careful when fertilizing and work out the right dose precisely, because too much can kill the plant. Ideally it should be NPK 10-10-10 and contain micronutrients.
Feeding normally begins in early spring and ends in autumn. In winter no fertilizer is needed. A freshly repotted plant must not be fertilized. Fertilizer can be applied only 4–5 weeks after the start of the growing season, once the bonsai has rooted in 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 trees and conifers. Start misting when the warm weather sets in, in spring, and continue until leaf fall begins. In summer it’s best to mist every day, though of course there is no need on rainy days. Mist your bonsai when you water it.
Some water-soluble fertilizers are also intended for foliar spraying. This encourages lush, healthy leaves that don’t fall ill so easily. There are also water-soluble foliar feeds whose spraying gives quite a good effect. If necessary, spray with dissolved fertilizer or foliar feed once a week, or as often as you apply fertilizer to the soil.
Diseases and pests
Like all plants, bonsai get diseases and are attacked by pests. So it’s best 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.
