The flora is rich and diverse, but not all species are able to survive in harsh climatic conditions. One of the key characteristics of flora representatives is winter hardiness. It is she who determines the viability of plants in a particular area. Based on the frost resistance of the flora, it is necessary to select biological organisms in the open ground.
The concepts and features of winter hardiness and frost resistance of plants
Their ability to withstand low temperatures (within + 1 … + 10 degrees) for a long period of time directly depends on the cold resistance of plants. If representatives of the flora continue to grow with negative thermometer readings, they can be safely attributed to frost-resistant plants.
Winter hardiness is understood as the ability of plants to continue their vital activity in unfavorable conditions for several months (for example, from late autumn to early spring). Low temperatures are not the only threat to flora representatives. The unfavorable conditions include sudden temperature changes, winter drying out, damping off, prolonged thaws, freezing, soaking, sunburn, wind and snow loads, icing, return frosts during the period of spring warming. The reaction of a plant to the aggressiveness of the environment determines its winter hardiness. This indicator does not apply to constant values; it can periodically decrease or increase. Moreover, the same type of plants has a different level of winter hardiness.
Frost resistance zone in Russia
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Frost resistance is difficult to confuse with winter hardiness – this indicator determines the plant’s ability to withstand negative temperatures. This feature is laid down at the level of genetics. It is the degree of frost resistance that determines the amount of water in the cells, which remains in a liquid state, as well as their resistance to dehydration and resistance to internal crystallization.
USDA Plant Hardiness Zones Table
| Frost resistance zone | From | To | |
| 0 | a | −53.9 °C | |
| b | −51.1 °C | −53.9 °C | |
| 1 | a | −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 | −1.1 °C | +1.7 °C |
| b | +1.7 °C | +4.4 °C | |
| 11 | a | +4.4 °C | +7.2 °C |
| b | +7.2 °C | +10 °C | |
| 12 | a | +10 °C | +12.8 °C |
| b | +12.8 °C | ||
How do plants become winter-hardy?
In addition to the genetic and hereditary factor, microclimate and growing conditions, there are other reasons why plants are resistant to low temperatures:
- the body’s defense system;
- stored for the period of cold weather carbohydrates and substances that can prevent the crystallization of water;
- structure, condition and type of soil;
- the age and hardening of the plant;
- the presence of top dressing and other mineral components in the soil;
- care in the spring and summer and preparing the plant for winter.
The winter hardiness of a biological organism can change throughout its life. It is believed that young representatives of the flora are less resistant to low temperatures than adults, which often leads to their death.
Representatives of winter-hardy plants
Barley, flax, vetch and oats are prominent representatives of cold-resistant plants.
Barley
Linen
She shouts
Oat
Frost-resistant species include perennial organisms of the root, tuber, bulbous type, as well as annuals – spring and growing – winter.
Note that in the cold season, it is the roots of the plant that are most susceptible to freezing. If negative temperatures prevail in the region, then without a thick layer of snow, the probability that they will survive is rather small. In such areas it is necessary to create an insulating layer by mulching the soil around the plant.
It is at the beginning of winter (in December, January) that plants have maximum winter hardiness. But with the onset of spring, even minor frosts can have a detrimental effect on a representative of the flora.
