frost hardy

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Plant species, populations or organs that are insensitive to low temperatures - a few degrees below the freezing point of water down to around −50 ° C - are referred to as frost-hardy . The term refers to plants in their natural environment, whereas imported or garden plants are more likely to be winter hardiness .

Every plant has an optimal temperature range for it, which corresponds to its natural range . If the air temperature is too high, it suffers a heat shock and, in extreme cases, dies. If the range is not reached, the plant is also damaged (see also cold shock ) and dies completely or partially. An important indicator is e.g. B. the shoot temperature . In plants from temperate latitudes, the elongation of the shoot begins at temperatures just above freezing point, in tropical species only at 12–15 ° C.

The frost hardiness is a property of almost all perennial plant species that live at latitudes above about 40 °. It depends on the one hand on the chemical consistency of the plant sap in the stem, stalk, leaves etc. and on their construction, and on the other hand on the supply of nutrients - especially potassium . This element is responsible for regulating the water balance in the cells . A sufficient or additional supply of potassium therefore has a positive effect on the frost hardiness of individual plants.

For the plant survival strategies at very low temperatures, see the special article Cold stress in plants .

Important influencing factors

The hardiness of frost depends essentially on several factors:

The origin of the plants also plays a major role, because the same species from the tropics or subtropics is usually less frost-resistant than plants from colder regions.

But you can noticeably influence frost hardness in cultivated land with the right care.

Plants sensitive to frost can survive down to a few degrees below zero if the period of hypothermia is short. A certain role can Resilience play. For more severe frost, however, the protoplasm of the cells must be freeze-resistant.

Examples of frost resistance

Apple and other local fruit varieties are almost all extremely hardy, peaches and apricots less so , both of which often tend to freeze on the branches or the trunk. The bushes native to middle and higher latitudes also have frost hardiness down to about −20 ° C or colder, while annual plants usually freeze off, rot or dry up in late autumn.

There are also several dozen frost-hardy species of palm trees . Of the approximately 2000 tropical species, however, some require minimum temperatures of 15 to 20 ° C. But there are some species that, according to their origin, can withstand light to medium periods of frost. They include u. a. the Chinese hemp palm ( Trachycarpus fortunei ), the z. B. occurs in East Asia and the Himalayas up to 2400 m altitude.

Literature and web links