Frosted plants

Plants and frost

Plants are living beings, and as such they have developed strategies to better withstand climate changes and weather conditions in the places where they live. Each plant has unique characteristics that make it suitable for living in the mountains in the cold, or in tropical forests or only in arid deserts. Evergreen leaves, deciduous leaves, succulent leaves, are all features that allow plants to survive in areas of natural origin. Many plants have instead been adapted to live in places very different from those of origin, subjecting them for years to temperatures and climates different from those natural to the plant, so as to "get them" in a colder or warmer climate than that from. This type of adaptation does not always work, so not all plants are suitable for cultivation anywhere on the globe.

Trees and shrubs

The most common plants in the areas where we live, also present in the natural state, are decidedly well adapted to the climate present in this area; viburnum, ilex, fruit plants can easily withstand the summer heat and winter frost, even if intense and prolonged in months.
To withstand the cold most of these plants tend to lose their delicate foliage during the coldest periods of the year; the evergreen plants on the other hand generally present coriaceous foliage, or covered with a waxy patina, which protects it from the cold.
In addition to this, most of the plants in our garden during the winter tend to go into vegetative rest, a sort of lethargy, during which the vital functions are slowed down as much as possible, so as to be able to face the frost.
This is because otherwise the water present in the green tissues of the plants could easily freeze, leading to the death of the tissue itself; it may indeed happen that a late frost, in March or April, leads to the death of the younger shoots of the early plants.
In principle, however, the plants present in the woods of northern Italy are very resistant to cold, and can withstand temperatures well below zero even for very long periods.

Bulbose and perennial

Most bulbs and perennials grow only in the summer, from March to April until October-November, with particular species beginning to wake up already in February.
These plants often have underground root systems with tissues that maintain nutrients and water over time, well below the ground, where frost does not penetrate; therefore with the arrival of the cold these plants lose the aerial part, the delicate leaves and the green sprigs, that would be easy prey of the cold. Throughout the winter we do not see much of these plants, which are in complete vegetative rest; but below ground they preserve all that the plant needs as soon as the warm season arrives: as the days get longer and the temperatures rise these plants quickly start to produce their buds, peeking out from under the ground to cheer up with colored leaves and flowers .
In the case of bulbous plants or particularly delicate perennials it is often recommended to mulch the soil where they are placed during the winter; this practice essentially serves to cover the underground roots, so as to remove them as much as possible from the frost.

Succulent plants

Most succulent plants do not like cold, and the fragile water-rich tissues tend to freeze, and therefore to rot, even if subjected only briefly to frost.
Many succulents, on the other hand, although naturally rich in water, have fairly leathery fabrics, and can withstand temperatures even close to -10 ° C.
To allow these plants to survive in cold temperatures, it is necessary that they are in total vegetative rest, so as not to have a large amount of water in the outermost areas, and not to present any type of bud or fresh tissue.
To get this hibernation it begins already in autumn suspending the waterings, so that the plant begins to slow down its vegetative activities; furthermore it is essential that during the cold months these plants do not receive watering. In the regions of northern Italy the only way that assures us that our succulents do not receive any kind of watering is to place them sheltered from the weather, such as in a cold greenhouse.
Surely then, if our succulents have been used over the years to spend the winter at home, with temperatures close to 20 ° C, we do not even think of leaving them on the terrace next winter: the thermal shock would be excessive, and would almost certainly lead to death of the entire plant.
In order to allow our succulents to withstand the cold we will have to adapt them to the harsh climate a little at a time, leaving them outdoors right away, and suspending watering already in autumn.
Even if a good part of the succulent plants bear temperatures even much lower than zero, not all do it, and not all can survive the cold if it lasts for whole weeks; therefore in doubt we place our succulents in a greenhouse, even without heating it.
There are succulents, like the sempervivum, well adapted to live even under the snow and in the most intense frost; they are succulents that have fairly leathery and rigid fabrics, and that tend to lignify in the older parts: in the case of decidedly very cold frost, the green parts tend to die, allowing the lignified parts to re-branch in spring.

Frosted plants: Bonsai

Most bonsai plants are generally small-scale specimens of trees commonly found in forests and city parks, and are therefore well resistant to cold, although very intense.
But remember that our bonsai live in a small pot, while the specimens of the same species grown in the ground can enjoy a root system sometimes deep even a few meters. So for example an elm tree in our garden can hardly be damaged by frost, as its roots are completely sheltered from the cold, because they are placed at a certain depth in the ground. The cousin placed in a small bonsai pot instead can suffer from cold, and also a lot, because the frost can penetrate to the center of its bread of roots, even damaging them severely.
So if we live in areas where frost is very intense, remember to cover our bonsai pots with non-woven fabric, to prevent the soil in which they are placed completely freezing.