In autumn, the length of daylight hours decreases significantly, the most difficult period in the life of citrus fruits begins. The day is very short, there are few sunny days. With a lack of light in a warm living room, the leaves of citrus fruits are formed very thin, large, and the shoots are overextended. With an increase in air temperature, the breathing of trees increases (carbon dioxide is released).
Trees consume a large amount of nutrients for breathing, and their accumulation, due to lack of light, is very slow. As a result, trees are depleted, their growth is weak, and flowers and ovaries, as a rule, crumble. With a large lack of light, leaves can also crumble. Consequently, in areas where daylight hours are shorter than 8 hours, trees must be transferred during the period of growth rest and put for wintering in colder rooms.
With a decrease in air temperature, the growth of trees stops and the energy of breathing (and the loss of nutrients) will decrease sharply. In the spring, when there is normal lighting, they form a powerful growth, buds and harvest .
Trees of all varieties of citrus grafted on trifoliate need cold wintering. During cold wintering, being in the period of growth rest, they retain foliage, and in spring they give normal growth and yield. Lemons grafted on lemon or orange seedlings grown from cuttings or air taps can be left in warm living rooms for the winter, but with good lighting and direct sunlight. Trees are best placed at the south windows or between the windows, with a protective screen from the heat rays of the radiator of the heating system.
Cold wintering is preferable for citrus fruits - the growth of leaves, shoots, buds and fruits stops at an average (in 5-10 days) air temperature of + 8-9 ° C. The best cold wintering conditions are an average air temperature of 7-8 ° C. And soft diffused light. Under these conditions, there is a normal vital activity of the leaves, but excessive evaporation of moisture and increased breathing are excluded. If the air temperature in the room is 3-5 ° C, but does not fall below zero, then citrus fruits withstand even severe darkening without any damage. You should not transfer plants from a warm room to a cold one, it is better to put them there in advance and prepare them for wintering. During cold wintering, it is impossible to raise the air temperature in the daytime above 15-17 ° C.
From cold soil (below 10-12 ° C), the roots very slowly absorb moisture, and the leaves evaporate it the more the higher the air temperature. As a result of daytime overheating, trees can shed leaves and not yield. For the same reason, watering trees growing in a warm room with cold water is very dangerous. It is impossible to bring plants from a cold room to a warm one without first heating the soil. The higher the soil temperature, the more active the absorption of moisture from the soil, the less moisture deficit in the leaves. In winter, the air temperature in the room should not be allowed to drop below zero, as trees can suffer from frost. Watering plants is rare. During cold wintering, the soil in the pots is slightly dried (when compressed into a lump, the soil should crumble slightly ).
In the room, trees are watered with heated water (5 ° C higher than the temperature in the room) until the soil is completely saturated. It must be remembered that with excess moisture, causing a lack of air, the roots will die, and the tree can drop leaves. The lack of moisture in the soil is indicated by the curling of the leaves by the boat with the scattering of the soil during compression. Dry air is especially dangerous in winter. The drier the air, the more moisture the citrus leaves evaporate and this can affect the future harvest. In rooms (with heating or solar heating), the air can be overheated and dried out. In these cases, the room must be ventilated, lowering the temperature to 15-18 ° C, sprinkle the trees, and water the soil.
In rooms where it is very hot in winter, water from the soil evaporates very quickly and watering is sometimes required more often than in summer. Do not forget to feed citrus fruits once a month in the autumn-winter period. And of course, if citrus fruits winter in a warm room and the temperature cannot be reduced, then additional lighting is needed. For the normal development of plants, two 40 W fluorescent lamps are sufficient for one window sill, the lamps are placed 15-20 cm from the crown of the plant or placed vertically in the corners of the frames. When ventilating the premises in winter, make sure that cold air does not fall on the crown, for this install a protective screen made of polyethylene, so that cold air flows around the plants, goes to the side or to the ceiling. And one more tip on reinforced concrete, marble, metal windowsills put a piece of foam or a plaque and only then put pots with plants.
Article by Alexander Mikhailovich Zaitsev Alex, photos by Alex and RSN