Climate zone 6a. Climatic zones of plant frost resistance. Particularly frost-resistant species

The main factor determining the choice of new perennials for a garden, it is a climate. It is especially important to know whether this species will overwinter in a given region or not. In nurseries, a frost hardiness zone is usually indicated for each plant. From it you can find out how low temperatures a plant can withstand and decide whether it is worth buying.

What are hardiness zones?

Initially, the definition of climatic zones for frost resistance was developed by the United States Department of Agriculture (USDA) for the needs Agriculture. 13 climate zones have been identified based on minimum winter temperatures by regions. Then the system was refined and improved. The data is summarized in the following table:

Zone		from	before
0	a	< –53,9 °C
0	b	-53.9°C	-51.1°C
1	a	-51.1°C	-48.3°C
1	b	-48.3°C	-45.6°C
2	a	-45.6°C	-42.8°C
2	b	-42.8°C	-40.0°C
3	a	-40.0°C	-37.2°C
3	b	-37.2°C	-34.4°C
4	a	-34.4°C	-31.7°C
4	b	-31.7°C	-28.9°C
5	a	-28.9°C	-26.1°C
5	b	-26.1°C	-23.3°C
6	a	-23.3°C	-20.6°C
6	b	-20.6°C	-17.8°C
7	a	-17.8°C	-15.0°C
7	b	-15.0°C	-12.2°C
8	a	-12.2°C	-9.4°C
8	b	-9.4°C	-6.7°C
9	a	-6.7°C	-3.9°C
9	b	-3.9°C	-1.1°C
10	a	-1.1°C	1.7°C
10	b	1.7°C	4.4°C
11	a	4.4°C	7.2°C
11	b	7.2°C	10.0°C
12	a	10.0°C	12.8°C
12	b	> 12.8°C

All zones in the US and Canada have been marked on the maps, taking into account mountain climate zones and coastal areas. Later, frost resistance zones were also determined for Europe.

For Russia, they are indicated approximately and are not a recommendation for growing certain types of plants. However, every gardener must know which climatic zone of frost resistance his region belongs to, so as not to be disappointed in the spring.

More detailed map winter hardiness zones for the European part of Russia:

for China:

for Ukraine:

for Belarus:

Factors that determine the zone of frost resistance

The specific minimum winter temperatures in the region depend on the geographical latitude, on the relief, on proximity to the ocean and air humidity.

Geographic latitude determines the value solar radiation received by the surface of the earth. In the southern regions, it is larger, so the climate is hotter there. But this is not at all the determining factor. By geographical latitude London is located to the north of Kyiv, but in Kyiv there are often twenty-degree frosts in winter and it belongs to the 5th zone, and in the south of England the grass turns green in winter. The south of England is classified as hardiness zone 9 due to its proximity to the Atlantic Ocean and the warm Gulf Stream. In Kyiv, the climate is close to continental, with dry summers and frosty winters.

The southern coast of Crimea belongs to zone 7, and the steppe Crimea to zone 6. The mountains protect the coast from northern winds, so palm trees, cypresses, wisteria and magnolias grow on the coast, and in other parts of the peninsula they freeze out in winter.

The frost resistance zones of Europe are distributed rather than from north to south, but from west to east - this is how the Atlantic affects the climate. Winters in Eastern Europe are noticeably harsher than in Western Europe.

Local conditions affecting the winter hardiness of plants

Do local conditions always correspond to the climate zone in terms of frost resistance? This question can be answered by many garden plant nursery owners. Surely they will confirm that even within their region, some varieties acclimatize perfectly and develop normally in certain areas, while in neighboring ones, literally at a distance of 50 km, there are serious problems with wintering.

This is due to the terrain, the height of the snow cover in winter, and the proximity of large water bodies. For example, Quebec in Canada is in zone 4, but plants grown there are designed for zones 5 or 6. The peculiarity of Quebec is that the height of the snow cover is always high there and there are no large temperature fluctuations. Snow serves as a reliable protection for plants.

Another example is the small village of Waksmund in the Polish Carpathians, where temperatures often drop to -35°C in winter, where the record for minimum winter temperatures for the region is -49°C. It is located near Krakow, where average temperature winters are -5.5°C, and the minimum record was recorded in 1929 and it is only -32°C. The fact is that it is in the area of \u200b\u200bthis village that cold and heavy air masses from the mountains descend down the slopes, creating such a paradox.

Climatic zone and plant features

When choosing new plants for your garden, you should take into account not only the winter hardiness zone, but also the characteristics of these species. Very often, perennials for the 4th frost resistance zone do not withstand the milder winters of the 5th or 6th zone. Why is this happening?

When making a decision before buying, it is useful to carefully study the properties of the plant and recommendations for care. An example is the features of growing some ( , ). They often do not tolerate winter, but this is not due to frost. The reason is prolonged thaws. These groundcovers do not like excess moisture in cold soil. If the winter is frosty without thaws, everything is fine; if frosts alternate with thaws, they will not overwinter. The problem can be solved by planting them on slopes where water does not linger.

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 area climatic conditions are not the same. It is well known that with south side houses are 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.
By using 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, making 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 trunk whitewashing fruit trees in November, shading evergreens with covering material in February or from autumn will help to avoid frost and sunburn in conditions of sudden temperature changes and weather changes.

Table of frost resistance zones:

Zone	From	Before
0
1	-45.6 °C	-53.9 °C
2	-40°C	-45.6 °C
3	-34.4°C	-40°C
4	-28.9 °C	-34.4°C
5	-23.3°C	-28.9 °C
6	-17.8 °C	-23.3°C
7	-12.2°C	-17.8 °C
8	-6.7 °C	-12.2°C
9	-1.1°C	-6.7 °C
10	-1.1°C	+4.4 °C
11	+4.4 °C	+10°C
12	>+10°C

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 given plant able to 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 all the variety of winter hardships - that is, not only bitter frosts, but also thaws, and sudden temperature changes 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. In 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 wood freezes more often than bark.

4. Winter hardiness depends only on the plant itself.

Although the ability to overcome winter problems really laid down in each tree or shrub in the genes, 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 bountiful harvest, poor nutrition or other difficulties, its winter hardiness can be significantly reduced.

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 increase again, 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 imperceptibly continues to develop (in particular, future inflorescences continue to form inside the buds).

8. During spring frosts the buds freeze the most. Ties are more stable.

In continuation of the decrease in frost resistance, which begins in the middle of winter, in the spring the plant continues to lose resistance to cold. 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 indicate foreign sources, - empty information for a Russian summer resident.

Although the division of plants according to their suitability for different climatic zones was proposed by the US 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). Let's say for central Russia usually recommend plants intended for the 5th zone and below.

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 relatively delicate plants like roses or grapes still successfully winter in cold zones under special shelters. Therefore, one can rely on the band principle only approximately.

Winter hardiness and frost resistance of plants The concepts are different, although they are close in meaning.

winter hardiness- this is the ability of plants to withstand a complex of environmental influences during the winter and early spring periods. This includes the ability to resist spring burns, low temperatures, weathering, soaking, the ability to withstand frequent temperature changes.

Frost resistance- this is only the ability of the plant to tolerate low temperatures.

Frost resistance zones (USDA zones)

These are the areas into which the territory is divided depending on the average value of the annual minimum temperature. These data were obtained on the basis of many years of statistical observations, but at the present time this division is being seriously criticized.

For entrance area it is better to use resistant plants that are decorative both in summer and in winter. It makes no sense to list them, because. such plants in garden centers There are so many and new ones appear every year.

In general, there is a tendency that those plants that were previously considered not particularly resistant do well in colder climates.

So, the rhododendron does not look particularly attractive at sub-zero temperatures.

Example: in Belarus with proper fit mahonia, holly, rhododendrons, some roses, boxwood, lavender, and other plants of a higher climatic zone winter well without shelter.