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 it is always warmer on the south side of the house, 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.
With the help of the correct placement of plants (in a warm and calm place), as well as the use of covering materials (spunbond, foliage, spruce branches, hilling, etc.) and “laying” the shoots to the ground for the winter, you can increase the climatic zone of your site by 1-2 units. It also helps to improve the soil regime (for example, the introduction of clay on sandy soils, the introduction 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 |
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 the minimum winter temperatures by region. Then the system was refined and improved. The data is summarized in the following table:
| Zone | from | before | |
| 0 | a | < –53,9 °C | |
| b | -53.9°C | -51.1°C | |
| 1 | a | -51.1°C | -48.3°C |
| b | -48.3°C | -45.6°C | |
| 2 | a | -45.6°C | -42.8°C |
| b | -42.8°C | -40.0°C | |
| 3 | a | -40.0°C | -37.2°C |
| b | -37.2°C | -34.4°C | |
| 4 | a | -34.4°C | -31.7°C |
| b | -31.7°C | -28.9°C | |
| 5 | a | -28.9°C | -26.1°C |
| b | -26.1°C | -23.3°C | |
| 6 | a | -23.3°C | -20.6°C |
| b | -20.6°C | -17.8°C | |
| 7 | a | -17.8°C | -15.0°C |
| b | -15.0°C | -12.2°C | |
| 8 | a | -12.2°C | -9.4°C |
| b | -9.4°C | -6.7°C | |
| 9 | a | -6.7°C | -3.9°C |
| b | -3.9°C | -1.1°C | |
| 10 | a | -1.1°C | 1.7°C |
| b | 1.7°C | 4.4°C | |
| 11 | a | 4.4°C | 7.2°C |
| b | 7.2°C | 10.0°C | |
| 12 | a | 10.0°C | 12.8°C |
| 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.
A more detailed map of 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 amount of solar radiation that the earth's surface receives. In the southern regions, it is larger, so the climate is hotter there. But this is not at all the determining factor. According to the geographical latitude, London is located 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? Many pet owners can answer this question. garden plants. 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 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 the average winter temperature is -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.
The individual features of the 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 conditions temperature regime during dormancy, for favorable wintering and successful reproduction. 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: precipitation, wind, icing, thaws, frosts.
Freeze or NOT freeze...
Combining plant species in accordance with their temperature requirements, nurseries of 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, while its counterpart, 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 lowest temperatures in 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 better to collect as much information as possible from various sources, talking on gardening forums, visiting flower growers' websites, 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. Such measures include: feeding plants with 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 plant for winter 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 in general 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 the root system penetrating deep into the ground not only freezes less, but also better provides the entire plant with nutrients, strengthening its immunity and increasing winter hardiness. Given this circumstance, young plants, especially those planted in autumn, must be carefully covered even in the southern regions of 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 the wintering period, to the ground surface, such shrubs as: large-leaved hydrangea, and, in more severe wintering conditions, become semi-shrubs, and the leaves of the arctic cinquefoil, introduced into a warmer region, lose part of the dense pubescence covering their leaves.
|
PLANT GROUPS BY FROST TOLERANCE |
PLANTS NAME |
Particularly frost-resistant speciesfrom -35°С |
birch drooping- Betula pendula elderberry red– Sambucus racemosa Derain white– Cornus alba Derain blood red– Cornus sanguinea Caragana treelike– Caragana arborescens Kostenets hairy- Asplenium trichomanes Linden— Tilia Siberian larch– Larix sibirica Japanese leaflet - Phyllitis japonica Goof silver- Elaeagnus commutata penstemon brilliant– Penstemon nitidus Penstemon hard-haired - Penstemon hirsutus foxglove penstemon— Penstemon digitalis Penstemon vertical— Penstemon strictus Rosa femoralis— Rosa pimpinellifolia Smolevka stemless- Silene acaulis Sorbarony alpine– Sorbaronia alpina |
Frost-resistant speciesfrom -25°С to -35°С |
Armeria maritime- Armeria maritime Common privet- Ligustrum vulgare common hawthorn– Crataegus oxyacantha Hamamelis virginiana-Hamamelis virginiana Double source reed - Phalaroides arundinacea Imperata cylindrical— Imperata cylindrica Viburnum ordinary– Viburnum opulus scalloped chestnut, or American- Castanea Dentata Kochedyzhnik female- Athyrium filix-femma meadow foxtail– Alopecurus pratensis magnolia siebold- Magnolia sieboldii Miscanthus giant- Miscanthus "Giganteus" miscanthus sinensis, or Chinese reed- Miscanthus sinensis Soapweed officinalis- Saponaria officinalis Amethyst fescue- Festuca amethistina Common bracken- Pteridium - aquilinum foxtail pennisetum- Pennisetum alopecuroides Penstemon bearded-Penstemon barbatus penstemon sprawling or serrated– Penstemon diffusus rose wrinkled— Rosa rugosa dog rose— Rosa canina Lilac Hungarian— Syringa josikaea Common lilac— Syringa Vulgaris Pine small-flowered - Pinus Parviflora variety "Hogoromo" Yew canadian- Taxus canadensis Chaenomeles japanese, or japonica- Chaenomeles Japonica |
Non-frost-resistant speciesfrom -17°С to -23°С |
Buddleya alternate-leaved- Buddleja alternifolia Wolfberry Gutta- Daphne x Houtteana Gledichia three-thorned - Gleditsia triacanthos Wisteria profusely flowering, or many-flowered- Wisteria floribunda Rough action - Deutzia scabra Honeysuckle brilliant– Lonicera nitida Imperata cylindrical— Imperata cylindrica Crested chestnut, or Japanese- Castanea Crenata himalayan cedar- Cedrus deodara Cortaderia Sello, or Pampas grass-Cortaderia Selloana (cultivar "Andes Silver") Tulip Liriodendron, or tulip tree-Liriodendrontulipifera Holly holly– Ilex aquifolium oriental plane tree, or Chinar-Platanus orientalis Plum serrate— Prunus serrulata Yew berry-taxus baccata |
Heat-loving speciesfrom -12°С to -17°С |
Araucaria Chilean- Araucaria araucana Wolfberry odorous, or fragrant - Daphne odorata wolfberry silky- Daphne sericea Chinese wisteria - Wisteriachinensis Maiden's grapes are three-pointed, or ivy grapes- Parthenocissus tricuspidata Cork oak- Quercus suber Itea virginiana— Itea virginica Kamasis rooting,or Tekoma taking root-Campsis radicans Campsis grandiflora, or Chinese- Campsis grandiflora Atlas cedar- Cedrus Atlantica Lebanese cedar— Cedrus libani cypress evergreen-Cupressus sempervirens . Palm maple or fan- Acer palmatum meadow foxtail– Alopecurus pratensis magnolia grandiflora- Magnolia grandiflora Common almond- Prunus communis Sisyurhynchus Bermuda- Sisyrinchium bermudianum |
2012, . All rights reserved.
Garden roses are rather capricious plants with high requirements for the climatic zone of cultivation. In variety descriptions, flower growers often come across such a characteristic as the "USDA zone". To understand what this marking means and how to choose a rose variety, taking into account the climate, is described in the proposed material.
Meaning and Characteristics of USDA Zones
Climate zoning is an artificial division of territories that helps gardeners understand whether a particular plant can withstand certain conditions. The intensity of their growth, abundance of flowering, life expectancy and resistance to diseases depend on the adaptability of roses to the climatic zone.
Climate as a whole is a multicomponent concept. It includes many characteristics: average summer and winter temperatures, rainfall in different time year, number of sunny days per year, length of daylight hours, prevailing winds, etc. Zoning territories taking into account all these parameters is quite difficult, because even within the same geographic latitude they can fluctuate greatly. Therefore, a system was adopted that highlights one characteristic - the minimum winter temperatures. So the zonesUSDA - 'these are hardiness zones.
The USDA system was developed by the US Department of Agriculture and today includes 13 main zones with two sub-zones each:
| Main zones and subzones by systemUSDA | Minimum temperatures in winter, 0 C | |
| I | Ia | Up to -51.1 |
| Ib | Up to -48.3 | |
| II | IIa | Up to -45.6 |
| IIb | Up to -42.8 | |
| III | IIIa | Up to -40 |
| IIIb | Up to -37.2 | |
| IV | IVa | Up to -34.4 |
| IVb | Up to -31.7 | |
| V | Va | Up to -28.9 |
| Vb | Up to -26.1 | |
| VI | VIа | Up to -23.3 |
| VIb | Up to -20.6 | |
| VII | VIIa | Up to -17.8 |
| VIIb | Up to 15 | |
| VIII | VIIIa | Up to -12.4 |
| VIIIb | Up to -9.4 | |
| IX | IXa | Up to -6.7 |
| IXb | Up to -3.9 | |
| X | Xa | Up to -1.1 |
| Xb | Up to +1.7 | |
| XI | XIa | Up to +4.4 |
| XIb | Up to +7.2 | |
| XII | XIIa | Up to +10 |
| XIIb | Up to +12.8 | |
| XIII | XIIIa | Up to +15.6 |
| XIIIb | Up to +18.3 | |
Tip #1 In descriptions of varieties of roses, as a rule, the mainUSDA zone. It indicates only the frost resistance of the variety, however, when buying, it is important to take into account other characteristics. For example, if a rose is suitable for frost resistance, but not suitable for drought resistance, it is better to refrain from purchasing it.
USDA climate zones in Russia
On the territory of Russia there are 9 main frost resistance zones according to USDA. Roughly they are distributed as follows:
First in the region of Yakutia.
Second- in Central Siberia, the Komi Republic.
Third– Eastern and Western Siberia, Kola Peninsula, Kamchatka.
4th- South-Eastern Siberia, Khabarovsk Territory.
Fifth- the middle Volga region, the Urals, the Central European part of Russia, the North-Western part of Russia.
sixth- lower Volga region, Voronezh, Kaliningrad region.
seventh- Rostov-on-Don, northern regions of the Stavropol Territory.
eighth- Astrakhan, Volgograd, the main part of the Stavropol Territory, the mountainous regions of the North Caucasus.
ninth- Krasnodar Territory, Crimea, foothills of the North Caucasus.
In the Yakutsk region, the coldest point of the Northern Hemisphere is also located - in the area of the village of Oymyakon. Here, winter temperatures drop below -70 0 С.
Tip #2 global changes climate make their own adjustments to the mapsUSDA. It is difficult to define clear boundaries today. The correct tactic for determining your zone is to collect statistical data on winter temperatures over the past 5-10 years.
Rose Varieties for Different USDA Zones
There are so many varieties of roses today that you can choose the right one for almost any USDA zone, except for the first, with extremely low frosts. For example:
| ZoneUSDA | rose variety | Variety |
| IIb | David Thompson | Hybrid Rose Rugosa |
| IIIb | William Baffin | Canadian rose |
| IV | Prairie Joy | shrab |
| V | Schneewittchen | floribunda group |
| VI | Leonardo da Vinci | floribunda group |
| VII | Yellow Fairy | polyanthus |
| VIII | Amazing Grace | Hybrid Tea |
| IX | Climbing Gold Bunny | Climbing |
Current Questions About USDA Rose Zones
Question number 1. Can a variety recommended for Zone III be grown in USDA Zone II?
Can. A number of agricultural techniques allow you to raise the microclimate in the area by 1 or even 2 zones. First of all, this is a competent selection of a landing site. If you plant a rose under the southern wall of the house, firstly, it will be securely covered from the cold wind, and secondly, it will be better illuminated and heated by the sun (See also the article ⇒). The second moment is preparation for wintering. Rosa needs to ensure good ripening of the shoots with the help of potash top dressing and reliable winter shelter. Finally, soil conditions play a role. If, when planting, the clay content in the soil is reduced and its humus content is increased, the roses will winter much better.
Question number 2. Will a hardy USDA zone III rose grow in a warm zone VI climate?
Frost-resistant roses are successfully grown in the south. But in this case, it is important to take into account the resistance of the variety not so much to freezing as to damping off. In warm, humid winters, the root collars of some varieties hardy roses can get wet affected by fungi. Therefore, it is important to provide them with excellent drainage. It is better to plant such roses on an elevated place. IN landing pit you need to lay a good baking powder - better not sand, but agroperlite. Mulch trunk circle should be dry mulch, not prone to waterlogging and caking. It is not necessary to cover roses planted in a zone warmer than recommended for the winter.
Determining the climate zone is important when choosing plants for a garden. Climate zones– a universal system for determining the cold resistance of plants.
Climate zones
Quite often when buying planting material garden plants or reading the description of plants in reference books, you can find links to maps of climatic zones. For example, zone 3 or zone 5-6. What are these zones, and what do these numbers mean?
For the first time, the division into climatic zones and their definition was made in the United States by the Agricultural Department. The division was made according to the principle minimum temperatures in winter in 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 with which you can easily determine the climate zone of your region:
The method, of course, is universal, however, gardeners, when buying certain plants, should not forget that in addition to cold resistance, other indicators can also affect plant growth (for example, the level of precipitation in the region or soil type).
In a special issue of our training magazine, only winter-hardy plants that are resistant to our climate. Represented practical examples combinations of plants in a flower garden or in a group for shady and sunny places. One of those magazines that you will always have at hand!
