Bonsai care (juniper on a rock)
Location
Juniper is not a houseplant, so it should spend most of the year outdoors. It is a light-loving plant, but it also grows well in partial shade. Keep it in a bright spot, but shield it from the scorching midday sun in summer. 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 a while, the plant can still get the water and nutrients it needs thanks to those deep roots. Confined to a pot, a bonsai has no way of directing its own root growth where it needs to go. 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 regulate the plant’s temperature and protect it from overheating. As long as the soil is moist, a plant can keep developing normally even in very high temperatures. When water is lacking, “scorch” spots appear on the leaves and shoots, and in the end this causes the plant to dry out.
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 according to need. 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 do not draw up a schedule along the lines of: “The bonsai must be watered once a day, in the evening.” Some species need soil that is 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 state of the soil every day and water when 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 relatively hard. 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 considerably lighter. Late watering is hard to spot on conifers. While on deciduous trees even a few hours’ delay can make the leaves droop, on conifers as much as a week may pass before you realize you have been consistently underwatering the tree. The first sign is that the new needles weaken and droop. Water with ordinary tap water. 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. A plant grown on a rock is much harder to keep in check. Make sure that after watering, the water penetrates well into the soil; otherwise only the surface may get wet while the soil deeper down stays dry. So first, using a small watering can, pour water slowly over the spot where the plant is planted in the rock, wait for it to soak in, and add more, until you are sure the soil is completely wet. After that, water the moss-covered soil.
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). 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 only water in the morning or at midday, the soil will soon dry out and the plant will effectively spend the whole night in dry soil. In autumn, when the sun is no longer as fierce, you can water your bonsai at any time of day, though morning is best. As for overwatering: when the soil around the roots is constantly wet, the amount of oxygen in the soil drops, which then causes the fine roots to deteriorate. The damaged roots begin to rot, and if this 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 your bonsai thoroughly, let the soil dry out gradually, and only then water again. Prolonged rain can also leave the soil in a pot waterlogged. 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, throughout 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. So bringing a bonsai into the warmth in winter simply 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 very harsh, a bonsai needs no special conditions for overwintering. But in regions where winter temperatures regularly drop low (-5°C and below), the plant must be protected from frost. This applies especially 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 severe 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 it, a bonsai may be damaged or even die. How a plant copes with abnormally high heat depends on its own heat tolerance and on how long the high temperatures last during the day.
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 hot weather, leaf temperature can reach a critical point. Wilting leaves are the first symptom of water shortage. In extreme heat, a plant 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 these conditions the plant becomes less resistant to diseases and pests. These processes are hard to spot on a conifer, however, because its 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 place 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 does not dry 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 plant gets from air and water, a plant must obtain macro- and microelements from the soil. The macroelements are nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). Various microelements 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. This applies particularly to the macroelements. An excess or shortage of any one of them has a noticeable effect on a plant’s development. For example, nitrogen is needed to regulate growth, for the leaves and for fruiting. A nitrogen deficiency soon shows itself in 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 makes the plant resilient 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 normal metabolism in the plant. Because there is so little soil in a pot, the nutrients are soon used up. So regularly applying a fertilizer that contains all these elements is just as essential as watering. Without supplementary feeding, a plant develops poorly, its leaves and needles lose color, and it falls prey to disease more easily. You can use either organic or mineral fertilizer for 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 a solid, in granules. Liquid fertilizer is dissolved in water at a given dose, and the plant is then simply watered with the solution. A plant absorbs 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 on the soil surface in special small baskets. With each watering a certain amount dissolves and slowly feeds the bonsai. You can order special bonsai fertilizer online. If you cannot find such a fertilizer, you can use a 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 use one that dissolves well in water, as this is more convenient. The packaging always lists the composition in percentages (NPK) and how much water it should be dissolved 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 microelements. Fertilizing usually begins in early spring, in March, and ends in autumn, at the end of September. At Samto Kimia you can buy the fertilizer “Kristalon 20-20-20”. Dissolve 1 teaspoon in 1.5 liters of water.
Misting
Misting is essential for both deciduous and coniferous plants. Start misting when the warm weather arrives in spring, and continue until the leaves begin to fall. In summer it is best to mist every day; naturally, in rainy weather there is no need at all. Mist your bonsai when you water it.
Some water-soluble fertilizers are also intended for foliar spraying. This promotes the growth of lush, healthy leaves, and the leaves are less prone to disease. There are also water-soluble foliar feeds, and spraying with them gives quite good results. If it is 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 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.
