USDA zones for garden roses. Climatic zones of plant frost resistance Climatic zone 6

Individual characteristics development of each plant, as well as its distribution area, are primarily determined by the main characteristics environment such as temperature and rainfall. Therefore, when acquiring new plants for the garden, it is very important to determine their need for the amount of heat needed during the growing season, as well as the temperature conditions during the dormant period, for a favorable wintering and successful breeding. Such indicators for plants are: cold resistance, frost resistance and winter hardiness.

Cold resistance and frost resistance of plants reflects their viability at low temperatures: cold resistance - up to 0 ° C, and frost resistance - from 0 ° C and below.

The winter hardiness of plants is a kind of indicator of the result of wintering plants, reflecting their reaction to the sum of any changes in environmental characteristics in winter period: precipitation, wind, icing, thaw, frost.

Freeze or NOT freeze...

By combining plant species in accordance with their temperature requirements, nurseries from various countries have created schematic maps, according to which it is possible to determine the frost resistance of representatives of a particular species, depending on the region of growth. Each of the zones marked on the map falls within the temperature range characteristic for the viability of the determined plant species, taking into account a short-term decrease in the lower temperatures that are safe for this species.

However, it should be noted that in any region tied to a certain frost resistance zone, there may be exceptions not only in terms of climatic characteristics (as a microclimate), but also depending on the growing conditions of a particular plant. For example, the same species, tied to the same zone, grown on an open hillside, can freeze out, while its fellow, on the edge of the forest, calmly overwinter under leaf litter. In addition, the mapping of plant hardiness is based on the readings of the lower temperatures of the area over the past decade, which means that the figures obtained in the next decade may be different. Thus, when determining the frost resistance of plants according to the map, one should not forget that such a division - conditionally and completely rely on it - is impossible. It is best to gather as much information as possible from various sources, communicating on the forums of gardeners, visiting the sites of flower growers, as well as from printed publications: books, newspapers and magazines. However, in this case, it must be borne in mind that some varieties of the same species may differ significantly in frost resistance.

Hardiness zones

1st — from -46°C and below

2nd - from -37ºС to -46ºС

3rd - from -34ºС to -37ºС

4th - from -28ºС to -34°С

5th - from -23°С to -28°С

6th - from -18°С to -23°С

7th — from -12°С to -18°С

8th — from -7° to -12°С

And suddenly it overwinter...

In any case, choosing for your garden plants recommended for zones located to the south, you can try to compensate for the lack of heat by preparing in advance the conditions aimed at the successful wintering of the new candidate. These measures include: plant nutrition potash fertilizers(in August - September), increasing air humidity (spraying plants, planting close to natural and), improving illumination and hardening.

True, if everything is clear with illumination (you just need to choose the brightest place in the garden), then hardening is a lengthy process that requires a lot of time and individual approach to every plant. The success of this procedure will be complete only when properly combined with other methods of care: timely transplantation and correct pruning plants, the use of fertilizers, systematic and high-quality watering. And all this in combination with normal weather conditions. Under adverse environmental conditions, most representatives of the flora are generally able to go into a state of forced rest, while maintaining viability, which in itself is not very good, because in this case, a weakened and unprepared for winter plant can simply die as a result of wintering. This is especially true for heat-loving southerners - sometimes a period of relative rest is observed in them even with slight drops in temperature. That is why, for example, roses give gardeners so much trouble - during thaws, they quickly begin to wake up and release leaves, which then freeze slightly. As for plants native to areas with frosty winters, for such representatives, a state of deep dormancy is a common phenomenon caused by necessity, but this does not save them from return frosts, to which, however, most plants as a whole are subject.

We increase winter hardiness

But if return frosts, despite the cold resistance of plants, can damage the buds, flowers and leaves of a specimen of any age, then the stems, roots and rhizomes of well-rooted plants suffer less with age. The growing bark becomes more durable, and penetrating deep into the ground, root system not only freezes less, but also better provides the whole plant nutrients, strengthening its immunity and increasing winter hardiness. Given this circumstance, young plants, especially those planted in autumn, must be carefully covered even in southern regions Russia. This is especially true for wintergreen and evergreen species wintering under snow. In snowless winters, they definitely need it, which, in the case of tall specimens, is not easy to build. It should be noted that the snow cover generally facilitates wintering for many plants. Its presence protects the soil surface from thawing during short-term thaws, thereby reducing the risk of damage to the root system from sudden temperature changes; although an abundance of snow can threaten any plants with elementary decay due to the fact that melt water stagnates near the roots, simply not having time to soak into the frozen ground.

Sometimes it happens…

Having acclimatized, some species try to adapt to new conditions, which may affect their external phenological characteristics. For example, shrubs that freeze during wintering, to the ground surface, such shrubs as large-leaved hydrangea, and, under more severe wintering conditions, become semi-shrubs, and arctic cinquefoil leaves, introduced into a warmer region, lose part of the dense pubescence covering their leaves.

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1. Extreme frost kills plants.

In fact, it is not the frost itself that causes suffering to plants, but the ice crystals formed under its influence in the tissues, which can damage living cells. The defrosting mode is also important. If a hardened plant is cooled under conditions that do not rapidly form ice, and then thaws very slowly, it can withstand even very deep freezing. Almost 50 years ago, Russian scientists in the laboratory managed to successfully freeze blackcurrant shoots to -253 ° C (!), And in the future, the “experimental” developed absolutely normally and bloomed safely! Success was not hindered by the fact that the experimental varieties - Laxton and Leah 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, and the apple trees growing there were not affected, which 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 a special term - "frost resistance"). The concept of winter hardiness is much broader and means the ability to endure the whole variety of winter hardships - that is, not only bitter frosts, but also thaws, and sharp drops temperatures from warm to cold, and so on.

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

In the same plant, different parts react to frost in different ways. At fruit trees The "weakest link" is the roots: depending on the crop and rootstock, they usually cannot withstand temperatures below -9 -10°C. Fruit buds are always more tender than growth buds, and wood freezes more often than bark.

4. Winter hardiness depends only on the plant itself.

Although the ability to overcome winter problems is indeed in the genes of each tree or shrub, a lot 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, too abundant a harvest, malnutrition or other difficulties, its winter hardiness may decrease significantly.

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

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

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

The usual cause of damage is not frost, but March temperature drops. The daytime sun heats the areas of the bark, which locally lose their temper and begin to function as in spring. But at night, the temperature drops, and the hurried parts of the trunk can be damaged. With this feature, the recommendation, incomprehensible to many, to whitewash the trunks at the end of winter, and not in the spring, is connected.

7. All the time from the end of leaf fall to the beginning of bud break garden plants are sleeping.

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

Immediately after leaf fall, the plants enter a state of deep dormancy. They need it, and until it ends, no heat can "awaken" them from sleep. Then deep peace passes 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 it gets warmer. Outwardly, both states look exactly the same. The 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, buds freeze the most. Ties are more stable.

In continuation of the decrease in frost resistance, which begins in the middle of winter, the plant continues to lose resistance to cold in the spring. Therefore, the ovaries are always more tender than the flowers, and the flowers are more damaged by frost than the buds. For the same reason, unfolded leaves freeze more than recently bursting buds.

9. Climate zones, according to which the cold resistance of plants is indicated by foreign sources, is empty information for a Russian summer resident.

Although the division of plants according to their suitability for different climatic zones was proposed by the United States Agricultural Department (USDA), in Russia it can also be guided by - after all, our territory also captures several climatic zones. Zones are allocated on the basis of the lowest temperatures recorded in these territories. At the same time, zone 1 is the coldest (there are frosts below -45 °), and zone 10 is the warmest (below -1 ... + 4 ° the thermometer does not fall). For example, for central Russia, plants intended for the 5th zone and below are usually recommended.

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

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

Russia is the largest state in terms of area, which is territorially located on the continent of Eurasia. the Russian Federation has a huge extent from north to south and from west to east. Her climatic conditions quite varied.

What are climatic zones?

Main characteristic separate zones is the climate - the interaction of temperature, humidity, air currents, solar intensity. Natural-territorial complexes have the character of latitudinal or sublatitudinal bands encircling the entire territory the globe. They differ in climatic conditions, soil cover, relief features, representatives of flora and fauna. On the territory of Russia, climatic zoning is applied. The state is located in the following zones:

• arctic;
• subarctic;
• moderate;
• subtropical.

Territorial division

The first belt covers the islands, as well as the coast of the North Arctic Ocean. On the territory located from the East European Plain and Western Siberia to 60 degrees north latitude, a subarctic climate dominates. Most of Russia is located in the temperate zone. Which can be divided into:

• temperate continental,
• continental,
• sharply continental,
• monsoon.

The territory of the European part of Russia is located in the temperate continental climate zone. Western Siberia and the territory of the extreme southeast of the East European Plain are located in the zone of the continental climatic zone. The territory of Central Siberia is a zone of a sharply continental belt. For Far East characterized by a monsoonal climate.

The smallest is the territory located in the subtropical climate zone. This is the Black Sea coast.

The delimitation of the territory of Russia

The climatic zones of Russia can be determined using a special temperature map. The territory on the map is divided into regions with similar natural conditions. Each area is characterized by an average annual minimum temperature range. The dates of the first autumn and last spring frosts can also be additionally indicated.

The natural and climatic zones of Russia are located in the temperature range from minus five in the warmest regions to minus sixty in the coldest. You can determine the region in which the desired site is located simply by looking at the map. Or, if greater accuracy is required, you can calculate it yourself by obtaining the arithmetic mean of the temperatures in the selected zone over the past ten or more years.

Eternal Frost Zone

The first climatic zone of Russia is tundra or arctic and subarctic. It can be attributed most Republic of Sakha (Yakutia). So, in its eastern part, average annual temperatures prevail, reaching minus forty-five degrees Celsius. 1 climatic zone of Russia is characterized by very cold, long winters with little snow and relatively short warm summer. This zone is characterized by a short frost-free period. This condition has a huge impact on the development of the flora. Grow in this area dwarf trees and shrubs.

For growing crops, this climatic zone gives only a few warm summer months, during which the permafrost recedes and frees up small patches of land for planting for the most stubborn and resourceful farmers. Nevertheless, the widespread use of greenhouses, frost-resistant and early-ripening crops makes it possible to harvest almost all known vegetables and fruits even under these harsh conditions.

Taiga climatic zone of Russia

A vast territory can be attributed to the second climatic zone. This is almost the entire area located between European part in the west and the third climatic zone in the east, stretching along the entire coast. This zone extends from Karelia to Kamchatka. Winter temperatures are moderate. However, the territory located in the east of this zone has more severe winters. So, in Eastern Siberia, a harsh winter period with little snow is accompanied by a decrease in air temperatures to minus forty or forty-five degrees Celsius. The climatic zone of Russia 2 is characterized by very severe weather conditions. Increased dampness contributes to soil cover with mosses. The soil is cold and wet. Near water bodies, the soil temperature is somewhat warmer, but even this is not enough for the production of crops. Also a complicating factor can be considered a strong freezing of the earth in winter.

Forest-steppe and steppe climatic zones of Russia

Climate zones three and four include the most densely populated part of the country. This strip is located all the way from the Murmansk and Arkhangelsk regions practically through the entire European part of Russia to the border with Kazakhstan and ends in the Altai Republic.

Also, the 3rd climatic zone of Russia captures the Far Eastern regions of the country along the entire eastern coast and includes parts of the regions. These are the Chukotka Autonomous Okrug, the Kamchatka Territory, the Magadan Region, the Khabarovsk Territory, the Sakhalin Region, the Primorskaya Region and the Jewish Autonomous Region. The monsoon climate prevails in this area. Cold snowy winters give way to cool and wet summer period. Frequent fogs and typhoons are typical.

Steppe - 4th climatic zone of Russia. Territorially includes the Lower and Middle Volga regions, North Caucasus, Southern Urals. As well as the southern regions of Western and Eastern Siberia. This zone is characterized by cold winters and dry summers. In central Russia, one can single out the territory adjacent to the shores of Lake Baikal. Here, due to geographical factors, a kind of temperature oasis has formed.

Dry steppe climate zone

This region is geographically located from the Eastern Ciscaucasia to the Sub-Ural Plateau. Also, the fifth climatic zone includes areas of the Kulunda steppe and territories located in the intermountain basins of Tuva and Transbaikalia. The area is characterized by dry summers with moderate temperatures. Winter frosts are heterogeneous throughout the territory. In the eastern regions of the fifth zone, more severe winters are observed.

Sixth-ninth climatic zones

Based on the map of climatic zones in Russia, built on long-term observations and analysis of temperature regimes various parts country, we can say that the entire territory of the country is located in the temperature regions from the first to the ninth.

The climatic zones of Russia 6-9 include mainly the southwestern regions of the country. These natural complexes can be characterized as follows:

• 6 - desert-steppe;
• 7-desert;
• 8-foothill semi-desert;
• 9-mountain.

The belt extending from the sixth to the ninth zone provides the most favorable conditions on Russian territory. The southern coastal region along the Caspian Sea can be assigned to zone seven, while the warmest zone is six.

The southeastern region of the Russian Plain and part of the Caspian Lowland are occupied by deserts and semi-deserts. These climatic zones of Russia are characterized by high summer temperatures and low ones in winter. A small amount of precipitation has an impact on the aridity of the climate. This zone is characterized by drought-resistant representatives of the flora.

In the zone of deserts and semi-deserts special place occupies the region of the Volga delta and the Akhtuba floodplain. The life-giving moisture of the river turns the territory into a green oasis.

The warm mild climate of the Caucasus makes it possible to include this territory in zones nine and eight. They can be described as quite soft and warm winter. The temperature regime of this period practically does not go into the negative temperature range. This factor contributes to the rich diversity of vegetation.

In conclusion

The climatic zones of Russia are diverse. Knowledge about each of them is indispensable for Everyday life and are used in a wide variety of industries. These or other natural conditions impose certain restrictions both during construction and when using this or that equipment. When administering economic activity the climatic conditions of the zones must be taken into account. The nature of Russia continuously challenges man, trying to test his strong-willed and spiritual qualities. But no doubt whatever difficult conditions no matter what dangers lurk, a person will always find a rational solution and a way out of difficult situation, and the earth will be covered with sprouts of young plants, new buildings will appear, and nature will submit to man.

References to maps of climatic zones (more precisely, winter hardiness zones, or plant frost resistance zones) are often found in international horticultural reference books. Winter hardiness zones, or frost resistance zones, are a handy tool for a gardener that will help you navigate when choosing plants and, if necessary, find suitable way winter shelter

Climatic zones - zones of winter hardiness or frost resistance of plants

Definition 13 climatic zones (zones of winter hardiness / frost resistance of plants) was developed by the US Department of Agriculture ( USDA) based minimum winter temperatures by region. Initially climate zone system used for the needs Agriculture, and later it began to be actively used by gardeners. This system is primarily suitable for such big countries, like Russia, the USA and Canada, whose territories lie in several climatic zones.

Minimum winter temperatures, on the basis of which are determined climatic zones (frost resistance zones) depend both on the geographical latitude of the region, and on its proximity to the ocean, as well as on the presence of mountains, lowlands, water bodies and other features of the relief. So, for example, the south of England and Kyiv are located approximately at the same geographical latitude. At the same time, the south of England belongs to hardiness zone 9 due to proximity to Atlantic Ocean and the warm current of the Gulf Stream, and Kyiv is located on the territory of the continent, far from the ocean and belongs to climate zone 5.

When deciding on the purchase of a particular plant, it should be borne in mind that a suitable winter hardiness / frost hardiness zone does not guarantee that the plant will grow well in your garden. Gardeners should take into account factors such as soil type, rainfall, temperature differences between day and night, daylight hours, heat and humidity. Many regions with absolutely different types climate fall into the same climatic zone (frost resistance zone / winter hardiness zone) due to the coincidence of the maximum-low temperatures. However, not all plants will grow and develop equally well in any of these regions.

Table 13 climate zones (plant hardiness zones) USDA

Climatic zones of Russia and the former USSR, map (USDA frost resistance zones)

Unfortunately, detailed zones of frost resistance / winter hardiness of plants have not been developed either in the USSR or in Russia. Based on the USDA map of world climate zones and the map of European climate zones (see below), it is possible to determine the climatic zones (zones of winter hardiness / cold hardiness of plants) of Russia and the former USSR. Here is a map I collected using graphic materials from the Internet:

AT recent times counters of shops and markets are full of exotic plants for our country. Yes, and familiar cultures are replenished with new varieties and varieties. Sellers assure that all these crops are zoned and perfectly adapted for growing in our difficult climate. But is it really so?

The climate of our country, characterized by warm or even hot summers, but cold and long winters, is naturally not suitable for all flora. Assess the ability of plants to withstand cold winter helps the concept called winter hardiness. Some (mosses and lichens) perfectly tolerate even the lowest winter temperatures, others (birch, oak) can only grow in more benign conditions, and still others (magnolia, oleander) are not at all adapted for harsh winters.

What plants are adapted for our climate knows, perhaps, everyone experienced gardener. But what to do with the novelties of the market, how to find out if the newly acquired green pet will survive the harsh winter? In fact, there is no problem here - reference books, documents and labels of specimens from nurseries indicate the frost resistance zone suitable for the plant. Let's see what it is.

What are frost hardiness zones

Frost resistance zones (or winter hardiness) are climatic regions of the globe suitable for growing certain types of plants. They are based on a temperature scale showing the average annual minimum temperature in degrees Celsius or Fahrenheit.

At present, the most comprehensive scale of hardiness in general use is the so-called USDA scale or zones.

USDA zones

The USDA scale was first developed by the US Department of Agriculture for the needs of farmers and crop producers, and then the proposed zoning began to be used throughout the world. The scale includes 13 zones (from 0 to 12), each of which is divided into 2 more subzones, the boundaries of which were determined on the basis of the minimum average annual temperatures. At first, only the territory of the United States was described, and then other countries. Now all regions of the globe belong to one or another zone on the USDA scale, and all plant species are divided according to their adaptability to different climatic conditions.

For example, a plant described as "zone 10 hardy" means that it can withstand a minimum temperature of -1°C. A more resistant plant, “zone 9 hardy”, can withstand a minimum temperature of -7 °C, etc.

USDA zoning is currently the universal scale of frost resistance used by modern farms. However, it has many disadvantages and does not take into account whole line critical factors, such as:

• Snow cover height. It is known that snow perfectly protects the root system of plants from frost, so crops that freeze out in snowless regions can survive well where there is a lot of snow in winter.

[!] Plant breeder from Poland noticed one interesting feature: azaleas dying of cold in Eastern Europe, wintered well in the Moscow region, where the climate is much more severe. It turned out that the rhododendrons were protected by snow, which did not allow the root system to die.

• Temperature changes. Many cultures are afraid not so much of frost as of sudden changes in temperature in winter. A sudden thaw, causing the snow to melt, and an equally sudden cold snap, leads to the death of the roots. That is why a number of plants, such as some types of bamboo, which are able to withstand very coldy, cannot survive in our climate.

[!] In the 60s of the last century, due to such a sudden drop winter temperature(from -1°C to -29°C), the maple collection of the Botanical Garden of Moscow State University was severely damaged.

• Spring frosts are another factor hindering the cultivation of heat-loving species. In our country, this problem is especially relevant: in the middle lane, frosts can return even at the end of May.

[!] You don't have to look far for examples. The May cold of 2017 killed a significant part of the grapes in the Crimea.

• Average annual rainfall. Humidity is an important climatic parameter that affects, among other things, the adaptation of plants. For example, some crops tolerate dry cold air well, but do not survive in humid climates.
• Other factors: the difference between day and night temperatures, terrain (presence of uplands and lowlands), soil types, daylight hours, wind rose, etc.

Russia, divided into USDA climate zones, looks something like this:

Some cities of our country belong to the following frost resistance zones: zone 1 - Tiksi, Batagai, zone 2 - the greater territory of Russia, Krasnoyarsk, Irkutsk, Novosibirsk, zone 3 - Khabarovsk, Magadan, Vorkuta, zone 4 - Moscow and the Moscow region, Vologda, Arkhangelsk , Chelyabinsk, Ufa, zone 5 - St. Petersburg, Vladivostok, Voronezh, Bryansk, Saratov, zone 6 and 7 - Krasnodar.

As for the labels on plants from nurseries, for Moscow and St. Petersburg, you should choose crops acclimatized for zones 1-4, as well as 5a and, partially, 5b.

As you can see, USDA zoning is far from perfect, so work in this direction is constantly ongoing.

Alternatives

The flawed USDA system prompted a search for alternatives. And now they use not only the above concept, but also some others. Firstly, USDA zones have been added to and their number has been significantly increased. In addition, one of the means of determining frost resistance zones was the use of so-called "indicator plants". It is known that the range of some species is strictly limited depending on the climate, and therefore the presence of any indicator plant indicates that the territory belongs to one or another frost resistance zone.

In addition, some countries have developed their own climate maps based on long-term meteorological observations. One of these countries was the UK.

In 2012, the Royal Horticultural Society of the United Kingdom presented their plant hardiness rating. This rating describes all plants found in the UK and is widely used by English growers.

The English system of plant frost resistance consists of 9 parts:

• H1a (more than 15°C) - growing in a greenhouse;
• H1b (from 10 to 15°C) and H1c (from 5 to 10°C) - outdoor cultivation only in summer;
• H2 (from 1 to 5°C) - crops that can tolerate a slight drop in temperature, but are not resistant to frost;
• H3 (from -5 to 1°C) - crops that tolerate the climate of the coastal regions of Great Britain;
• H4 (from -10 to -5°C) - crops adapted to the climate of most of the UK;
• H5 (from -15 to -10°C) - crops adapted to the climate of most of the UK and withstanding a significant drop in temperature in winter;
• H6 (from -20 to -15 ° С) - frost-resistant crops that can grow throughout Northern Europe;
• H7 (less than -20°C) are the most frost-resistant crops.

Frost resistance zones in the USSR and Russia

In our country, work on determining frost resistance zones began at the beginning of the 20th century, and then continued after October revolution. And, although at first the maps were imperfect, and the climatic regions were too generalized, in the 60s the work was continued: the number of zones increased to 42 (up to 60 together with subzones). The work was called "Tree-cultivating regions of the USSR." In addition to zoning, work was also carried out to separate plants found in the USSR according to climatic regions. The list consisted mainly of tree crops, but the number of species included in it is very large - about 700.

The data obtained by Professor AI Kolesnikov, who supervised the work, summarized in the publication "Decorative Dendrology". This book is still relevant today.

With detailed description tree-cultural regions of the USSR you can familiarize yourself with.

The work did not stop there, and the detailing of zoning continued. Other factors that affect the winter hardiness of plants began to be taken into account: not only the minimum, but also the average annual temperatures of the winter and summer months, the average and minimum humidity, evaporation and annual precipitation. The number of frost resistance zones increased to 76, and the plants recommended for each zone were divided into three groups - “main”, “additional” and “auxiliary”:

• the main one is plants that are well acclimatized for the area,
• additional - crops that can grow in the considered climatic zone only under the condition good care(shelters for the winter),
• auxiliary - singly occurring plants.

Unfortunately, serious state research on this topic was no longer carried out, although both the climate and the assortment of plants have changed, and tremendous practical experience has been accumulated. From time to time, individual farms try to compile such maps, but due to lack of resources, their work is limited to individual areas.

How to increase the frost resistance of plants

In conclusion, I would like to give some tips from the practice of gardening. Many crops recommended for more favorable climatic zones, with proper care, it is quite possible to grow here. To increase the winter hardiness of certain species, it is recommended:

• Protect the root system from frost. This can be done with the help of coniferous spruce branches, dry fallen leaves, peat, sawdust, industrial covering material. Styrofoam, which has high heat-insulating properties, has also proven itself well.
• Cover not only the roots, but also above-ground part plants. Of course, it is difficult to protect the crown of powerful tree crops (although some gardeners manage to wrap the lower part of the trunks with cloth or polyethylene), but liana-like species and plants with flexible stems should be carefully laid on the ground and covered.

[!] It is especially important to protect young cultures, whose age is 2-3 years. Their root system is not yet fully formed and is located close to the surface of the earth.