What is climate zone 4 9. Minimum temperature (in o C)

Frost resistance zones

Frost resistance zones

Frost resistance zones (USDA zones) - geographically defined, vertically zoned areas according to the principle of the average value of the 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.

In connection with the intensive introduction of new for Russia types and forms of decorative garden plants, the question of the stability of introduced species is currently extremely relevant and widely discussed. It is known that the detrimental effect on plants has not middle level winter temperatures, and the most severe, albeit short-term frosts. In practice, the average of the absolute minima of air temperature is used as an indicator of frost hazard. The same climatic indicator was taken as a basis by the American dendrologist Alfred Raeder, whose reference book Manual of cultivated trees and shrubs hardy in Hoth America is still relevant. His reference book contains a map of the territory of the USA and Canada with the allocation of 7 winter hardiness zones. woody plants. For more than two and a half thousand species, a possible zone of their culture in open ground.

Later, this system was re-analyzed, refined and supplemented. Now 11 zones are distinguished: zone 1 - Arctic, 10 and 11 - tropics. In recent decades, the system of stability zones has been extended to Western Europe. Horticulturists and dendrologists in the US and Canada soon after its inception 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 introducers introduced into culture was compiled by the famous German dendrologist Gerd Krüssmann. On the European map of winter plant hardiness zones given in his monograph, it can be seen that the majority of Western European nurseries are located in zones 6 or 7, with a minimum temperature of -12 °C to -23 °C. BUT most of The territory of Holland, Belgium, France and England is located in zone 8 with a minimum air temperature ranging from -7 ° to - 12 ° C. The outskirts of St. Petersburg correspond to the -29 ° isotherm, delimiting the fourth zone from the fifth.

USDA zones

The existing zoning was developed by the US Department of Agriculture and subsequently became widely used (outside the US - mostly in horticultural literature).

There are thirteen main frost resistance zones from 0 to 12, and with an increase in the zone number, the average value of the annual minimum temperature rises (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 of the zones, many areas with a milder or more severe microclimate can be found. Plants are most frost-resistant at the beginning of winter (December, beginning of January) with the approach of spring, their frost resistance decreases.

Examples

see also

Notes

Literature

• Ir. M. H. A. Hofman; Drs. M. W. 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 site DIY.ru

Wikimedia Foundation. 2010 .

01.01.2012

This system (USDA-zoning) was introduced by the US Department of Agriculture, but it is also used in Europe.
Hardiness zones are a certain range of temperatures in which the plant stably overwinters.
The Moscow region is traditionally referred to as the 4th zone.
That is, if zone 4 is indicated on an imported plant, it is assumed that this specimen is able to overwinter in conditions, withstanding frosts down to minus 29 degrees.
However, there are many conventions in this topic.
There is convincing evidence of the successful cultivation of plants in the Moscow region classified both in the 5th and even in the 6th zones. For example, according to many reports, ginkgo winters well in the Moscow region, although it is classified as a 5th zone.
Winter hardiness also largely depends not only on the genetic properties of the plant, but also on its current state. Past illnesses, lack of minerals or too much big harvest weaken the living organism, and its resistance decreases. Plants for which proper care, shows the maximum winter hardiness inherent in this species.
Winter hardiness changes throughout the entire hibernation period of the plant: it reaches its peak by the end of deep dormancy (end of the year in middle lane Russia), and then decreases.
Transition period from hibernation in the growing season is quite complex. For example, at the beginning of spring, the bark of trees heats up during the day, and at night it cools sharply, which leads to its damage. Temperature fluctuations have a negative impact on the most vulnerable areas fruit trees- the lower parts of the trunks. Trees can be protected by whitewashing trunks at the end of winter.

Microclimatic factors affecting the winter hardiness of plants.

In addition to temperature, there are many additional factors that affect the development of plants: soil type, daylight hours, wind, humidity. It should be taken into account that the microclimate of areas within the climatic zone may not correspond to the baseline values.
Elevations, southern slopes, large reservoirs have a beneficial effect on plant growth, in contrast to lowlands and northern slopes. In the city, as a rule, the temperature is slightly higher than outside the city.
With careful observance of all the rules of agricultural technology, many trees and shrubs can be grown on the territory of colder zones in protected areas.
The plant can be suitable for five and more zones.
If your hardiness zone is colder than what is recommended for planting the selected plant, special care must be taken in deciding where to plant the seedling on the site.
Dry cold wind puts the development of evergreens at risk, as the process of evaporation from the surface of the leaves becomes more intense, and dehydration occurs. To avoid this problem, it is necessary to plant in places protected from the wind and ensure the correct development of the root system. For this, the soil must be deep, loose, permeable. Mulching works well.
wintering difficulties.
AT warm winters with abundant snow cover, plants are threatened with decay - exhaustion in a dark, waterlogged, warm environment, when plants "unscheduled" consume all their nutrients.
Wetting can occur in the lowlands during the period of snow melting or prolonged thaws: melt water is not absorbed into the soil and plants lack oxygen.
Lack of oxygen and mechanical pressures are often also due to the formation of ice crusts. Ice crust formation occurs if severe frosts occur after frequent thaws. The crusts are contact (tightly attached) or hanging (practically do not come into contact with plants, they are easy to destroy).
Bulging.
There may be frosts in the absence of snow cover or an autumn drought, or a thaw in which snow water has already been absorbed by the soil. In such conditions, freezing begins at a depth - where there is water. The layer of ice gradually increases and lifts, that is, “bulges out” the upper layers of the soil along with the plants, which leads to the breakage of the roots. Secondary rooting can save the plant from drying out, which can be stimulated with the help of timely rolling of the soil. Crops with roots capable of stretching are resistant to bulging.
Damage from winter drought (at the end of a snowless or little snowy winter with significant solar heating) are dangerous for fruit trees and shrubs in a number of regions of Russia. Under normal conditions, a stable winter cover protects the plant from drying out.

The area in which your garden plot, you can determine yourself - for this you need information about the lowest temperatures in your area over the past 10 years (you can choose a longer time period). Then we calculate the arithmetic mean of all values ​​and see what zone number it corresponds to.
It's obvious that this method cannot be considered absolutely accurate. For example, anomalous temperature jumps can affect the result of calculations. In addition, the same result can be obtained both with a large spread and with minimal fluctuations in values. It is believed that the territories of central Russia correspond to zone No. 5 and those below.
Below are two tables (table 1-short and more detailed table 2) by which the zone can be determined.

Table 1.
Zone Temperature
1 below - 45°C
2 from -45 to -40°C
3 -40 to -34°C
4 from -34 to -29°C
5 from -29 to -23°C
6 from -23 to -17°C
7 from -17 to -12° С
8 from -12 to -7° С
9 -7 to -1°C
10 from -1 to +5° С

Table 2.
Hardiness zone From To
0 a< -53.9°C
b -51.1°C -53.9°C
1a -48.3°C -51.1°C
b -45.6°C -48.3°C
2 a -42.8°C -45.6°C
b -40°C -42.8°C
3 a -37.2°C -40°C
b -34.4°C -37.2°C
4 a -31.7°C -34.4°C
b -28.9°C -31.7°C
5 a -26.1°C -28.9°C
b -23.3°C -26.1°C
6 a -20.6°C -23.3°C
b -17.8°C -20.6°C
7 a -15°C -17.8°C
b -12.2°C -15°C
8 a -9.4°C -12.2°C
b -6.7°C -9.4°C
9 a -3.9°C -6.7°C
b -1.1°C -3.9°C
10 a +1.7°C -1.1°C
b +1.7°C +4.4°C
11 a +4.4°C +7.2°C
b +7.2°C +10°C
12 a +10°C +12.8°C
b > +12.8°C

According to kr.ru

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 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 (or winter hardiness) zones are climatic regions 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 shortcomings and does not take into account a number of important 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 can withstand severe frosts, cannot survive in our climate.

[!] In the 60s of the last century, due to such a sudden drop in winter temperature (from -1°C to -29°C), the collection of maples suffered greatly botanical garden Moscow State University.

• 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 the 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 range of plants have changed, and a colossal practical experience. 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 improve winter hardiness certain types 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 the aerial part of the plant. Of course, it is difficult to protect the crown of powerful tree crops (although some gardeners manage to wrap lower part 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. Them root system not yet fully formed and is located close to the surface of the earth.

Frost resistance

Certain plants indicate in which hardiness zones they can grow in connection with the classification of the USDA (Ministry of Agriculture USA), widely used in the USA and increasingly popular in Europe.

This classification is based average minimum temperatures in certain areas. The smaller the zone number, the greater the frost resistance of plants.
In practice, the zone number placed on each plant indicates the degree of adaptability to low temperature endurance, i.e. the smaller the number, the greater the frost resistance and the less sensitivity to frost. Living in zone 7, it is better to choose plants from the same zone or a zone below. Plants from zones above the 7th may freeze slightly.

It must be remembered that the winter hardiness of plants depends on many factors., therefore, the division into frost resistance zones must be taken as indicative information. In each of the zones, many areas can be found with a milder microclimate or more severe than in the previous zone. Also in the garden, plants growing in a sheltered place near buildings tolerate more low temperatures than plants growing on the east side, where drying winds and early striking sun predominate.

It must also be remembered that plants are most hardy at the beginning of winter(December, beginning of January) with the approach of spring, their frost resistance decreases (they become unhardened). Even more hardy plants, well hardened, at the beginning of the growing season and leafing out, can be damaged even by slight frosts (eg Actinidia (Actinidia)). The greatest frost losses occur in February, March, the sunniest months, when, after a frosty night, the plants heat up and cannot withstand a sharp temperature drop. This is especially dangerous for evergreens. Covering such plants with a shade cloth or spruce branches coniferous plants may be adequate protection.

Young plants are always more sensitive than older ones. that are already deeply rooted. Therefore, frost-sensitive plants may require special protection and shelter for the first 2-4 years after planting. You can, for example, cover with straw, forming "stacks".

A significant difference in frost resistance is also found between different parts plants. Roots are several times more sensitive to frost than lignified shoots. In areas where there can be severe frosts without a thick layer of snow, it would be good to create an insulating layer yourself by mulching the soil around the plants, for example. bark. Also sprinkle the base of the plants to a height of 10-15 cm, which will ensure the preservation of buds from which plants can grow, even when the whole thing freezes. above-ground part. Mulching around plants is essential also in summer because it retains moisture in the soil and reduces weed growth. Protecting the roots from freezing is especially important if the plants are grown in containers on balconies and terraces.

USDA hardiness zones

The specified climatic zoning of territories is an artificial division of places for growing plants, based on the ability of plants to survive in winter conditions. This division is based on a long-term study of winter temperatures.

The assignment of a plant to a particular zone is based on knowledge of the variety's requirements for growth and development conditions. However, even in the same zone, climatic conditions are not the same. It is well known that the south side of the house is always warmer, and in a place protected from the winds (for example, a courtyard or urban development), even the largest "sissies" can grow. Therefore, the given zoning of plant varieties is rather conditional.
Via correct placement plants (in a warm and calm place), as well as the use of covering materials (spunbond, foliage, spruce branches, hilling, etc.) and “laying” shoots to the ground for the winter, you can increase the climatic zone of your site by 1-2 units. Improvement of the soil regime also helps in this (for example, the introduction of clay on sandy soils, the introduction of organic fertilizers, covering the soil with manure, mulching with sawdust, peat, etc.). Then, for example, in the conditions of the third climatic zone, it is possible to grow varieties belonging to the fourth or fifth zone without any problems. In addition, special events, such as whitewashing fruit tree trunks in November, shading evergreens with covering material in February or autumn, will help to avoid frost and sunburn in conditions of sudden temperature changes and weather changes.

Table of frost resistance zones: