Natural factors have a great influence on the cultivation of horticultural plants, that is, the natural conditions of a given region or site. Among the natural factors in the cultivation of horticultural plants, the most important are: climate, land relief, soil and water. Climate in many cases determines this, whether a given species or variety of tree, fruit bush or vegetables can be grown in one area or another, in one position or another. Also, due to the climate, we do not grow oranges in our country, lemons, dates, bananas or, on a larger scale, peppers, watermelons or eggplants; not everywhere and not always peaches are popular with us, morel, vine, melons, and even tomatoes.
The microclimate is also used in fruit and vegetable production, with its range covering a small area, often limited to a small place or even a specific position. It can be very variable, even in a relatively short range. For example, an east-west wall has walls with exhibitions – south and north. The first of them accumulates the maximum amount of heat due to strong sunlight. Thanks to this, plants with high heat demand are successful there, how: peaches, morel, winter pear varieties, from shrubs – vine, and from vegetables – pole beans, tomatoes. The position is on the other side of the wall, that is, on the north side, almost no fruit plants are suitable for cultivation, few vegetables, and of ornamental plants, only ivy can grow well. The local climate in natural conditions has, for example,: hills, depressions of the terrain, places sheltered by forests. We can also by appropriate treatments, e.g. by planting a hedge, green belts as windbreaks, create a favorable microclimate for the cultivation of horticultural plants.
As we know, climate comprises a group of atmospheric factors, operating in your area. Among these factors, they play the greatest role in horticultural production: temperature, precipitation, supplemented with watering, insolation and winds. Temperature is one of the most important climatic factors in the cultivation of horticultural crops. Each plant requires a certain amount of heat during its growing season to produce valuable crops and can withstand only certain minimum and maximum temperatures and limited temperature fluctuations.. Fruit trees and shrubs, as long-lasting plants that stay in one place for several to several dozen years, they may freeze during winter if the temperature drops too much, and even completely extinct. They are generally the most resistant in this respect: apple trees, then cherries and plums, the least: Italian nuts, apricots and peaches. The shrubs resistant to frost include currants, gooseberry and hazel, to less resistant – raspberries and strawberries, and to the fastest freezing – vine.
Sudden changes in weather are a very important factor influencing the frost resistance of fruit trees and shrubs. Warm and humid autumn and sudden frosts favor plants to freeze over. On the other hand, in the conditions of warm and humid autumn, the vegetation period of plants is extended, which is not conducive to their good preparation for winter rest. The sudden onset of severe frosts after the warm one causes similar effects, and even a dry fall. The lack of a slow transition to low temperatures prevents the plants from gradually adapting to them and they freeze easily with the onset of frost. The resistance of fruit trees to low temperatures during the winter period fluctuates greatly; under average conditions, fruit trees achieve maximum frost resistance around the middle of winter. Under normal weather conditions, the risk of fruit plants freezing up is greater than in the second half of winter, because there are large fluctuations in day and night temperatures and differences in the temperature of tree trunks on the southern side (in sunny weather) and north. As a result, trunks usually freeze on the south side, and as a consequence, open gangrene wounds develop on this side. Therefore, it is recommended to whitewash trees in December, that the sun's rays reflect from the surface of the trunks of the branches.
Not only the above-ground parts of fruit trees and shrubs freeze, but also their roots. Peaches are the most sensitive in this respect, pear trees and cherries; they freeze at a temperature of -12 ° C. Roots freeze relatively easily in shallow soils, with a defective structure, and badly grown. Among other factors, they have a great influence on the freezing of fruit plants: the location of the site (they increase the risk of basins and depressive basins), form of a fruit tree, his health, fruiting method and agrotechnical procedures carried out in the orchard quarters. Serious damage to fruit and vegetable production can be caused by spring frosts, that destroy flowers, even the leaves of fruit trees and shrubs, as well as sowing and planting of thermophilic vegetable plants.