Bonsai care (dwarf Alberta spruce)
Placement
The dwarf Alberta spruce (Picea glauca conica) is not a houseplant, so it should spend most of the year outdoors. Keep it in a bright spot but in the shade; it doesn’t like direct sunlight, especially in summer. For the best effect a bonsai should stand on its own: choose a spot where the miniature tree will show well and won’t be “overshadowed” by other objects. First of all, a bonsai should be placed so that the viewer can clearly see its front — the tree’s most attractive side.
Watering
A bonsai needs regular, careful watering. In nature, a tree’s roots grow deep into the ground. If it doesn’t rain for a while, the tree can still get the water and nutrients it needs through those deep roots. Under confined conditions, a bonsai has no way to steer its roots in the direction it needs. A bonsai grows in a very small amount of soil, so it depends far more on watering than a tree growing in nature does. It is also worth noting that on hot summer days, the movement of water through the tree and its evaporation from the leaves (or needles) regulate the plant’s temperature and protect it from overheating. As long as the soil is moist, a tree can keep developing normally even in very high temperatures. A lack of water causes the tree to dry out and die.
How much and how often to water
How often a bonsai needs watering depends on the conditions it’s 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 common misconception: that watering during the hot part of the day is harmful to the tree. In summer it is sometimes even essential to water a bonsai during the sunny part of the day. So don’t set yourself a fixed routine along the lines of: “The bonsai must be watered once a day, in the evening.” The dwarf Alberta spruce needs less moisture, but letting the soil dry out completely for even a day or two very often kills the tree. In summer be sure to check the condition of the soil every day and water whenever it is needed. Watch the moss first of all. It’s easy to tell when its surface is dry — it changes color. Use ordinary tap water for watering. Make sure the soil is soaked right through after watering; otherwise only the surface may get wet while the soil deeper down stays dry. In spring and summer a tree needs much more water than in late autumn or winter. In winter you may water the tree only a few times 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 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 tree will spend 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. As for overwatering: when the soil around the roots is constantly wet, the amount of oxygen in the soil drops. This then causes the fine roots to deteriorate. 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 a bonsai thoroughly, let the soil dry out gradually, and only then water again. Soil can also become waterlogged from prolonged rain. But even a week of non-stop rain will not harm the tree. The danger is when the soil stays saturated with water constantly, throughout the whole season. There is one more mistake people make with watering. In summer, after a brief shower, only the surface of the soil in the pot gets wet, while deeper down it stays dry. If you’re not sure the soil is thoroughly wet all the way through, water the bonsai as usual. In this case the extra watering will do no harm.
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 tree’s vitality as the period of active growth. That is why bringing a bonsai into the warmth in winter simply because it “might get cold” is fatal for the tree. Of course, bringing it indoors for a day or two to decorate the room will do no harm. But if it spends the whole winter in the warmth, it will certainly die.
In Tbilisi’s conditions a bonsai needs no special arrangements for overwintering. But if the temperature stays very low all day long (-10 and below), the tree 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. During such spells we can temporarily move it somewhere the frost won’t be as severe.
Protecting bonsai in summer
At temperatures above 30°C, unless we take special measures to protect a bonsai, the tree may be damaged or even die. How well a tree copes with 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 tree cools itself through its leaves, by evaporating water. In high temperatures it loses moisture quickly. 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 water shortage. In extreme heat a tree may go dormant prematurely (as it does in autumn). The leaves change color and drop — first those inside and at the bottom 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 as well. Under such conditions the tree becomes less resistant to diseases and pests. These processes are hard to spot on conifers, however, because their needles don’t give such a “signal.” That is exactly why conifers need special attention in summer. A tree 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. Don’t place a bonsai on a surface that gets 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 carbon (C), hydrogen (H) and oxygen (O), which a tree takes from air and water, a tree needs to take up 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, the macronutrients above all. An excess or shortage of any one of them has a noticeable effect on a tree’s development. For example: nitrogen is needed to regulate growth, for the leaves and for fruiting. A nitrogen deficiency soon shows up 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 tree’s development and root growth, and increases its resistance to drought and frost. Potassium helps the tree withstand stress (very high or low temperatures, too much or too little moisture). An optimal level of potassium improves the buds’ ability to survive the winter and the tree’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, the nutrients are soon used up. That is why regularly applying a fertilizer that contains all these elements is just as essential as watering. Without additional feeding a tree 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 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 set dose, and the tree is watered with the resulting solution as usual. Trees absorb liquid fertilizer quite 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 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 at garden centers or flower shops. As a rule, these contain all the elements plants need. For bonsai it is 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 tree. Ideally it should be NPK 10-10-10 and contain micronutrients. Feeding usually begins in early spring, in March, and ends in autumn, at the end of September. At Samto Kimia you can buy “Kristalon 20-20-20” fertilizer. Dissolve 1 teaspoon in 1.5 liters of water.
Misting
Misting is essential for both deciduous trees and conifers. Start misting once the warm weather sets in, in spring, and continue until leaf fall begins. In summer it is best to mist every day; naturally, there is no need to do so in rainy weather. Mist your 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 whose spraying gives quite good results. 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. That is why it is 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.
