Winter hardiness of ornamental plants. Cold hardiness zones

Zoning cultivated plants, is directly related to the definition of the so-called frost resistance zones - climatic regions to which they can correspond, as acceptable, from the standpoint of planting extensive (industrial) plantings. This concept is more strict than the general possibility of introduction various types plants, which allows for more extensive experiments under favorable microclimate conditions.

At the moment, the generally accepted international (American) classification is USDA zones, which contains 11 such gradients with transitional subzones a) and b) (), which, despite its limited flexibility, is still quite often used in our country as a guide.
Most of the temperate zone ( middle zone), with active agricultural activities, fits into the indicators of 3-7 climatic zones of frost resistance. A broad prospect for the introduction of various foreign crops of a temperate climate begins with zone 5, which corresponds to the scale of the average of the absolute minimums: −23.3 °C .. −28.9 °C

There is confusion in the understanding of these critical indicators for determining frost resistance zones, which are used in agrometeorology for agroclimatic zoning.
The first fundamental calculated parameter is the absolute annual minimum indicator, which characterizes the short-term (from several hours or more) setting of cold fronts, which can lead to significant freezing or complete death of the plant. It can be considered only in the context of a limited time frame - either for the period of all currently available observations (often, this is no more than 60-80 years of history), or within the initially specified framework: the latest climate norm - a period of 30 years of observations, or arbitrarily given period - 20, 40 or more years. To take into account the latest dynamics of climate change, a period of up to 10-20 years is considered. Considering what has been said, an answer in the spirit of “we don’t have -40” is not correct by definition; in the general case, such words do not characterize anything.
Another calculated parameter is more indicative - the average of the absolute minimums (as a rule, it is 1.5 times less than the previous indicator). To calculate it, absolute minimums are taken for each year, for the required period (usually over the last 10-20 years of observations) and averaged. This parameter is accepted as the unit of account when determining USDA zones.

Let's look at an example.
Let's take the absolute minimum data (Tn indicator) for the State Botanical Garden (GBS) of Moscow (the observation station at the All-Russian Exhibition Center is located several kilometers from the southern entrance), as a data source we will use the resource - http://rp5.ru/, look in the sections: Weather archive at the weather station / Weather statistics:
2005 .. -21.5 °C
2006 .. -30.8 °C
2007 .. -23.0 °C
2008 .. -18.3 °C
2009 .. -22.1 °C
2010 .. -25.9 °C
2011 .. -26.4 °C
2012 .. -28.5 °C
2013 .. -18.3 °C
2014 .. -25.4 °C

We get: the average of the absolute minimums over the last 10 years of observations will be (add all values ​​and divide by 10): -24 °C
Using the table of values, we will determine for Moscow GBS compliance with frost resistance zone 5b, which is typical only for the microclimate conditions of the city (the general frost resistance zone for the Moscow region will be an order of magnitude lower).

This frost resistance zone, if we take into account the latest climatic norm - 30 years of observations, runs, approximately, along the border: Minsk - Gomel - Bryansk - Kursk - Belgorod - Voronezh, which is the border, for example, of a possible industrial crop of cherries, but what else not enough for industrial apricot culture (varieties obtained on the basis of the common apricot genotype), or walnut.
One should always distinguish general recommendations by introduction (introduction) individual species plants within one climatic region - frost resistance zone, and the capabilities of a specific microclimate. As a rule, within the framework of one generalized zone of frost resistance, it is always possible to find (select): both more favorable, already transitional conditions for the next, more favorable neighboring zone, and aggravated conditions that should be perceived adjusted for one zone below. Also, the frost resistance of a tree considered as part of a forest biocenosis (forest population) and a separate open one is not the same thing. personal plot. The forest, on its own, is already the fundamental basis for the formation of microclimate and other factors that contribute to more adequate acclimatization of the species.
It should be taken into account that many non-regional plants exhibit increased sensitivity to environmental conditions uncharacteristic for them (humidity regimes, solar radiation, the nature of seasonal changes, etc.), which affects, among other things, the ability to reveal the full potential of the inherent genotypic frost resistance. For this reason, often in foreign nurseries, in relation to such foreign crops, two frost resistance zones are simultaneously designated - one for natural growing conditions (within their distribution area), and the second - in the introduction of specific local conditions, which, nominally (by default ) is set to -1 zone lower.

Work on reseeding (reproduction in generations) in new conditions of introduced species, as a rule, serves the purpose of normalizing (unlocking the full potential) genotypically inherent frost resistance, which for many plants is a realistically feasible task. But still, this reserve should not be unnecessarily exaggerated. In general, it cannot be higher than the frost resistance of a particular species, which is manifested in natural conditions along the northern border of its distribution, and certainly, it can be most fully revealed only in native conditions. So, for example, depending on the place of growth (nature of naturalization), as well as the source seed material, in a situation of full passage of all phases of vegetative development, the manifested frost resistance of the Manchurian nut, allowing it to go through the stage of winter dormancy without significant damage to the above-ground part, can vary from -44 ° C to -52 ° C or more degrees. At the same time, the ability, let’s move on to the example of the walnut, to endure winters with temperatures down to -40 °C in places of industrial culture (southern Ukraine, for example), and somewhere in the Moscow region, is completely different.
It would be more correct, as is recommended by many reference books, when determining frost resistance zones, to take into account another important interconnected indicator - the sum of active temperatures during the growing season (for the temperate zone, they most often focus on the sum of positive temperatures more than +10 °C), but this is already a topic for a separate discussion.

Mar 3, 2014 Alexei

Frost resistance zones

Frost resistance zones

Frost resistance zones (USDA zones) - geographically defined, vertically zoned areas based on the principle of the average annual minimum temperature based on long-term statistical observations. Frost resistance zones serve as a limiting climatic factor for plant life and, despite the subjectivity of such an assessment, are widely used in practice to describe suitable conditions natural distribution or cultivation of certain representatives of the flora.

Due to the intensive introduction of new species and forms of decorative plants for Russia garden plants, the issue of the sustainability of introduced species is currently extremely relevant and widely discussed. It is known that it is not the average level of winter temperatures that has a detrimental effect on plants, but the most severe, although short-term, frosts. In practice, the average of the absolute minimum air temperatures is used as an indicator of frost danger. The same climatic indicator was taken as a basis by the American dendrologist Alfred Roeder, whose reference book Manual of cultivated trees and shrubs hardy in Hoth America is still relevant. His reference book provides a map of the United States and Canada highlighting 7 winter hardiness zones woody plants. For more than two and a half thousand species, a possible zone of their cultivation in open ground is noted.

Later, this system was re-analyzed, refined and supplemented. Now there are 11 zones: zone 1 - Arctic, 10 and 11 - tropics. In recent decades, the system of hardiness zones has been extended to Western Europe. Gardeners and dendrologists in the United States and Canada soon after its creation adopted the concept of plant hardiness zones, with all its advantages and disadvantages. And over many years, largely through direct trial and error, most species of trees and shrubs have been assessed in terms of their assignment to a particular zone. If you use this method, then St. Petersburg is located almost on the border of zones 4 and 5.

After Raeder, the most complete summary of tree introduced species introduced into culture was compiled by the famous German dendrologist Gerd Krüssmann. The European map of winter plant hardiness zones given in his monograph shows that most Western European nurseries are located in zones 6 or 7, with a minimum temperature of - 12 ° C to - 23 ° C. And most of the territory of Holland, Belgium, France and England is in zone 8 with a minimum air temperature ranging from -7° to -12 °C. The outskirts of St. Petersburg correspond to an isotherm of -29°, delimiting the fourth zone from the fifth.

USDA zones

The current division into zones was developed by the US Department of Agriculture and subsequently became widely used (outside the United States - mostly in horticultural literature).

There are thirteen main frost resistance zones from 0 to 12, and as the zone number increases, the average annual minimum temperature increases (zone 0 is the coldest).

It is believed that the territories of central Russia correspond to zone No. 5 and those below.

It must be taken into account that the winter hardiness of plants depends on many factors, so the division into frost resistance zones should be taken as indicative information. In each zone there may be many areas with milder or more severe microclimates. Plants are most frost-resistant at the beginning of winter (December, early January); as spring approaches, their frost resistance decreases.

Examples

see also

Notes

Literature

• Ir. M. N. A. Hofman; Drs. M.V.M. Raveslot Winterhardheid van boornkwekeriioewassen. - 1998.

Links

• Data on winter hardiness zones in the Encyclopedia of Ornamental Garden Plants (Retrieved January 26, 2009)
• Climatic zoning. Winter hardiness zones. on the website DIY.ru

Wikimedia Foundation.

2010.

In fact, it is not so much the frost itself that causes suffering to plants, but the ice crystals that form under its influence in the tissues, which can damage living cells. The defrosting mode also matters. If a hardened plant is cooled under conditions in which ice does not form quickly, and then thawed very slowly, it can withstand even a very deep freeze. Almost 50 years ago, Russian scientists in laboratory conditions managed to successfully freeze blackcurrant shoots to -253°C (!), and subsequently the “experimental” ones developed absolutely normally and bloomed safely! Success was not hindered by the fact that the experimental varieties - Laxtona and Lia fertile - were by no means standards of winter hardiness.

2. Winter hardiness is the temperature in degrees that a given plant can withstand without loss.

For example, in a particular area one winter there was a frost of -38°C, but the apple trees growing there were not damaged - this means that the winter hardiness of these apple tree varieties is -38°C.

Winter hardiness is not just the ability of plants to withstand low temperatures (by the way, there is special term- “frost resistance”). The concept of winter hardiness is much broader and means the ability to endure all the variety of winter hardships - that is, not only bitter frosts, but also thaws and sudden changes temperatures from warm to cold, and so on.

3. The plant is monolithic in terms of frost resistance - all its parts either withstand or cannot withstand the same temperature.

Different parts of the same plant react to frost differently. U fruit trees“the weakest link” is the roots: depending on the crop and rootstock, they usually cannot withstand temperatures below -9 -10°. Fruit buds are always more tender than growth buds, and the wood freezes more often than the bark.

4. Winter hardiness depends only on the plant itself.

Although the ability to overcome winter problems is indeed in every tree or shrub's genes, much depends on its current state of health and on the conditions prevailing in a particular year. A strong, well-groomed plant always shows its maximum winter hardiness. If it weakens as a result of an illness, it is too bountiful harvest, poor nutrition or other difficulties, its winter hardiness may decrease significantly.

5. The frost resistance of a particular tree or shrub is the same all winter.

In autumn, each plant undergoes so-called hardening, during which its frost resistance increases. When a tree or shrub goes into deep dormancy, winter hardiness continues to grow. It reaches its peak at the end of deep rest (at middle lane for most plants this happens around the end of December). Then resistance to frost steadily decreases. It falls gradually and steadily, regardless of the weather, and is also lost sharply during each thaw. Moreover, the longer and warmer the thaw, the more frost resistance decreases. However, this process is partially reversible, and resistance can increase again, especially in cases where thaws are replaced by frosts not abruptly, but gradually. This is why the same apple tree can withstand a bitter cold of -35° in early December, but then suffer at -28° in early March. And in mid-May, its budding leaves may turn black after freezing at -6° C.

6. The lower parts of fruit tree trunks are the most “frozen”. After the winter has been endured, it is in these places that there are areas of dead bark.

The usual cause of damage is not frost, but March temperature changes. The daytime sun heats areas of the bark, which locally lose their hardening and begin to function as in spring. But at night the temperature drops, and hurried parts of the trunk may be damaged. This feature is associated with the recommendation, incomprehensible to many, to whiten trunks at the end of winter, and not in spring.

7. All the time from the end of leaf fall to the beginning of buds, garden plants sleep.

At this time, nothing changes in them, but if you transfer their branches to warmth, they will “wake up” and begin to bloom.

Immediately after leaf fall, plants enter a state of deep dormancy. They need it, and until it ends, no amount of warmth can “awaken” them from sleep. Then deep peace turns into forced peace. That is, the plants no longer need it, it’s just a way to survive further cold weather. At this stage, the buds can begin to bloom at any time as soon as the weather warms up. Outwardly, both states look exactly the same. A plant at rest only looks “lifeless,” but at the same time it continues to develop imperceptibly (in particular, future inflorescences continue to form inside the buds).

8. During spring frosts, the buds freeze the most. The ovaries are more stable.

Continuing the decline in frost resistance, which begins in mid-winter, in the spring the plant continues to lose resistance to cold. Therefore, ovaries are always more tender than flowers, and flowers are damaged by frost more than buds. For the same reason, unfolded leaves freeze more strongly than recently burst buds.

9. Climatic zones for which foreign sources indicate the cold resistance of plants is empty information for the Russian summer resident.

Although the division of plants according to their suitability for different climatic zones was proposed by the US Department of Agriculture (USDA), in Russia it can also be guided by - after all, our territory also covers several climatic zones. Zones are allocated based on maximum low temperatures, registered in these territories. At the same time, zone 1 is the coldest (there are frosts below -45°), and zone 10 is the warmest (the thermometer does not fall below -1...+4°). Let's say for Central Russia Plants intended for zone 5 and below are usually recommended.

10. Belonging to one or another climate zone number - comprehensive information on the winter hardiness of the plant.

A suitable “number” is not a guarantee of future happy life tree or shrub in a specific area. Why? Firstly, winter difficulties are not limited to frosts alone. Secondly, in each area the condition of the plants depends on many nuances: microclimate, moisture supply, soil, duration daylight hours- all this is not reflected in the zone number, although it is of enormous importance. Some weather “record” or “anti-record” can also confuse the cards. Opposite examples are also possible: some relatively tender plants like roses or grapes still successfully winter in cold zones under special shelters. Therefore, it is possible to rely on the band principle only approximately.

Determining the climate zone is important when choosing plants for the garden. Climatic zones are a universal system for determining the cold resistance of plants.

Climate zones

Quite often, when buying planting material garden plants or reading descriptions of plants in reference books, you can find references to maps of climatic zones. For example, zone 3 or zone 5-6. What kind of zones are these, and what do these numbers mean?

For the first time, divisions into climatic zones and their definition were made in the United States by the Department of Agriculture. The division was made according to the principle minimum temperatures V winter period By different regions. It turned out that this is a very convenient and universal way to indicate the cold resistance of plants. The system for determining cold resistance using climatic zones is very convenient for large countries, like Russia, whose territory covers several climatic zones.

Below is a table that will help you easily determine the climate zone of your region:

The method, of course, is universal, however, gardeners, when purchasing certain plants, should not forget that in addition to cold resistance, other indicators (for example, the level of precipitation in the region or the type of soil) can influence plant growth.

The special issue of our educational magazine contains only winter-hardy plants that are resistant to our climate. Practical examples of plant combinations in a flower garden or in a group for shady and sunny places. The magazine is one of those that you will definitely always have at hand!

Russia is a country that occupies a huge area. Many peoples and ethnic groups live on its territory. But, in addition to this, it is also divided into different climatic zones. Depending on this, different flora and fauna settle in different areas of the country. What are the climatic zones of Russia, what are the criteria for division and what are the features of these zones - read about all this in the presented article.

Total number of climate zones

Initially, you need to understand how many climate zones exist in general. So, in nature there are four of them (counting from the equator line):

• Tropical.
• Subtropical.
• Moderate.
• Polar

Generally speaking, the division into climatic zones occurs in accordance with the average temperature of the surface heated by the sun's rays. It should be noted that such zoning was based on many years of observations and conclusions drawn from analytical data.

About the climatic zones of Russia

What are the climatic zones of Russia? The country's territory is very large, which allowed it to be located in three of them. So, if we talk about zones, there are three of them on the territory of Russia - temperate, arctic and subarctic. However, the natural and climatic zones of Russia are divided according to meridians, of which there are 4 on the territory of the state, related to the 20th, 40th, 60th and 80th meridians. That is, there are four climatic zones, the fifth is called special.

Table of natural and climatic zones

There are 4 climatic zones in Russia. The table is presented for easier perception of information:

Considering the climatic zones of Russia, it should be noted that most of the country is located in the Arctic and subarctic zones. Also, quite a lot of territories occupy the temperate zone. There are not so many subtropics, it is less than 5% of the entire territory of Russia.

Arctic climate

It is necessary to start considering the climatic zones of Russia with the Arctic climate. It is characteristic of the special, as well as part of the 4th zone. Mainly located here arctic deserts, as well as the tundra. The soil hardly warms up, the sun's rays just glide across the surface, which does not allow the flora to grow and develop. The fauna is also scarce, the reason for this is the lack of food. Winter takes up most of the time, which is about 10 months. Behind summer period the soil does not have time to warm up, since the heat in the region of 0-+3 °C lasts no more than a couple of weeks. During the polar night, temperatures can drop to -60 °C. There is practically no precipitation, it can only be in the form of snow.

Subarctic climate

Widely distributed in Russia. So, it includes the 4th zone, as well as partially special and third. Winter is also long and cold, but less severe. Summer is short, but the average temperature is 5 degrees higher. Arctic cyclones cause strong winds, cloudiness, and there is precipitation, but not heavy.

Temperate climate

The 3rd and 2nd climatic zones of Russia belong to the temperate climate. Covers most of the country's territory. The seasons are clearly defined here, there is spring, summer, autumn and winter. Temperatures can range from +30 °C in summer to -30 °C in winter. For convenience, scientists divide this zone of Russia into 4 more:

• Moderate continental. Summer is hot, winter is cold. Natural areas can replace each other from the steppes to the taiga. Atlantic air masses predominate.
• Continental. Temperatures range from -25 °C in winter to +25 °C in summer. A large number of precipitation. The zone is formed mainly by western air masses.
• Sharply continental. Partly cloudy and little precipitation. In summer the soil warms up well, in winter it freezes deeply.
• Maritime as well as monsoon climates. Characteristic strong winds which are called monsoons. Precipitation is heavy and there may be flooding. Summer is not hot, the average air temperature is +15...+20 °C. Winters are very cold, air temperatures can drop to -40 °C. In coastal areas, winter and summer are more moderate.

Subtropical climate

1 climatic zone of Russia partially covers small area countries in the Caucasus Mountains region. Summer here is long, but not hot. In winter, the temperature does not drop below 0 °C. Due to the proximity of the mountains, there is quite a lot of precipitation, it can be plentiful.

There are no tropics or equatorial zones on Russian territory.

Road climate zones

Few people know, but there are also road climatic zones in Russia. They are divided according to the features of the building highways for a certain territory (depending on temperatures, precipitation and other climatic indicators). In this section you can find 5 zones.

The benefits of dividing into climate zones

Why distinguish climatic zones in Russia? Table 1 and Table 2 indicate that there are many of them. All this exists for convenience. Thus, this division is important for many areas of activity and knowledge. Most often, such zoning is important:

• For tourism business, resort planning.
• When constructing buildings, roads (including railways), communications design.
• When assessing the possibility of people living in a given territory.
• When planning the extraction of minerals and natural resources.
• When organizing the management Agriculture, farming.

Well, generally speaking, knowledge of climate zones helps many people improve their lives in different parts of the country. This knowledge helps many people optimize and develop a particular territory for living. For example, cold areas require large expenditures; in a temperate climate, it is best to breed livestock and grow useful vegetation.