Bonsai care (privet)
Placement
Privet is not a houseplant, so it should spend most of the year outdoors. It is a light-loving plant. Place it somewhere bright, but keep it out of direct sun, especially in summer. From June through August you can keep it indoors, in a well-lit spot. From September, be sure to move it back outside. Privet copes well with the Tbilisi climate.
Watering
Bonsai need regular, careful watering. In nature, a tree’s roots grow deep into the ground. If it happens not to rain for a while, the deep roots still allow the tree to get the water and nutrients it needs. Confined to a container, a bonsai has no way of sending its roots wherever they are needed. There is very little soil in a pot, so a bonsai depends on watering far more 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 growing normally even in very high temperatures. When water is 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 when 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 harms it. In summer, it is sometimes actually 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 becomes necessary.
There are a few simple signs that the soil is drying out: as the soil begins to dry, its surface changes color; the surface of dry soil is relatively hard. If your bonsai has been in its pot for a few months, you can also tell whether it needs water by lifting it. The difference in weight is quite noticeable – dry soil is considerably lighter. On deciduous trees, the first sign of late watering is drooping leaves and fresh shoots. Bonsai are watered with a special small watering can that delivers a slow, gentle flow. Pouring a large amount of water all at once washes away the soil surface and leaves hollows here and there.
Use ordinary tap water. Its drawbacks are chlorine and a high mineral salt content. After regular watering with such water, the surface roots and the rim of the pot become covered with a white crust, which you will need to remove 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. Quite often a bonsai sits in its pot in such a way that much of the water poured on runs off the surface and over the edge. In that case, pour the water slowly, only as much as the surface will hold without overflowing, wait for it to soak in, then add more, until you are sure the soil in the pot is wet right through. Water running from the drainage hole is the sign that the soil is thoroughly wet.
Suppose the soil in the pot has dried out completely. If you look at the pot closely in this situation, you will see that a gap has opened up between the pot and the soil. If we water it in this state, most of the water will run straight through the gap and out of the drainage hole.
In this case it is better to stand the plant in a vessel larger than its pot, pour in water up to the rim of the pot, and lift it out once the soil surface is wet. The excess water will drain from the drainage holes. In spring and summer the plant needs far 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).
The time of day you water a bonsai also matters. In late spring and summer, when temperatures are high, try to water in such a way 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 and the plant spends practically 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, though morning is best.
Now about overwatering. When the soil around the roots is constantly wet, the amount of oxygen in it drops. This in turn damages the fine roots. The damaged roots begin to rot, and if the process is not stopped, a large part of the root system gradually rots away. As a result, the tree first weakens and, if the situation is not corrected, dies. So once you have watered your bonsai thoroughly, let the soil dry out gradually and only then water again.
Persistent rain can also leave the soil in the pot too wet. But even a week of non-stop rain will not harm the plant. The danger is when the soil in the pot stays waterlogged constantly, for an entire season.
Winter care for bonsai
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. So bringing a bonsai into the warmth in winter simply because it “might get cold” is fatal for the plant. Of course, bringing it indoors for a day or two to decorate a room 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 needs no 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 freeze easily. In the Tbilisi climate the risk of freezing is lower. But if hard frosts last 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 may be damaged or even die. How a plant copes with abnormal heat depends on its own heat tolerance and on how many hours a day the high temperatures last.
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 it quickly loses moisture. When a bonsai gets too little water in the heat, leaf temperature can reach a critical point. Wilting leaves are the first symptom of water shortage. In severe heat, a plant may go dormant prematurely (as it does in autumn). The leaves change color and fall – first those inside and at the bottom 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 these conditions the plant becomes less resistant to diseases and pests. On conifers, however, these processes are hard to notice, because their needles don’t 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 in which 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 shade. Don’t set a bonsai on surfaces that get very hot in the sun: stone, concrete, metal. Try to raise the humidity around the bonsai: mist it more often and water 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, 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 others. All of these elements are vital to the plant’s existence, the macronutrients above all. An excess or deficiency of any 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 slower 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 gives the plant resilience to stress (very high or low temperatures, too much or too little moisture). The right amount of potassium improves the buds’ ability to overwinter and the plant’s resistance to fungal and bacterial diseases. Calcium is essential for a normal metabolism in the plant. Because there is so little soil in a pot, its nutrients are soon exhausted. That is why regularly applying a fertilizer that contains all of these elements is just as essential as watering. Without extra feeding, the plant grows weakly, its leaves and needles lose color, and it falls prey to disease more easily. You can use either organic or mineral fertilizer on a bonsai, but you must not mix the two and apply them together. There are fertilizers made specifically for bonsai that contain all the necessary elements. They come either as a liquid or in solid, granular form. Liquid fertilizer is dissolved in water at a set dose, and the plant is watered with the 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 put into small special baskets set on top of the soil. Each time you water, 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 general-purpose compound fertilizer sold in garden centers or flower shops. As a rule, it contains all the elements plants need. For bonsai, it is best to use one that dissolves well in water, as it is more convenient to use. The packet always lists the composition in percentages (NPK) and how much water it should be dissolved in. Take great care when feeding and work out the correct dose precisely, because too much can kill the plant. Ideally it should be NPK 10-10-10 and contain micronutrients. Feeding normally starts in early spring and ends in autumn. No fertilizer is needed in winter. Never feed a freshly repotted plant. Fertilizer can be applied 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 the warm weather sets in, in spring, and continue until the leaves begin to fall. In summer it is best to mist every day; naturally, there is no need to do so in rainy weather. Mist the bonsai when you water it.
Some water-soluble fertilizers are also intended for foliar spraying. This promotes lush, healthy leaves that are less prone to disease. There are also water-soluble foliar feeds that give quite good results when sprayed. If you need to spray with dissolved fertilizer or a foliar feed, do it once a week, or as often as you apply fertilizer to the soil.
Diseases and pests
Like all plants, bonsai suffer from diseases and are attacked by pests. That is why 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 correct doses and spray. Never spray a bonsai in an enclosed space.
