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Grapes are a southern culture. Thanks to the achievements of breeders, it was possible to advance it far to the north. Now growers harvest grapes in the northern regions. But only in a covering culture. Moreover, the acquired ability of grapes to endure severe frosts is directly related to the loss of large-fruitedness and taste.
But in terms of their taste, they cannot replace table varieties. When choosing them, be sure to consider the ripening time and the ability of the grape variety to resist adverse conditions.
Good table grape varieties that can tolerate low temperatures without shelter are not yet available. Many growers may disagree and will cite examples of excellent vine overwintering under sufficient snow cover. Yes, this method pays off. But where is the guarantee that there will be a lot of snow in winter? Not everyone has the opportunity to throw snow on wintering vines. Consequently, there is always a risk not only of being left without a crop, but simply of losing valuable varieties. What conditions allow grapes to successfully overwinter?
What temperature can grapes endure without loss
If you do not take into account the not so numerous varieties of grapes that can not freeze even at -30 degrees and below, the temperature from -18 to -25 for the vine is considered critical, the specific figures depend on the variety. For the roots of grapes, soil freezing below -7 degrees is dangerous.
Grapes are afraid not only of very low temperatures. No less detrimental to the vine and its sharp fluctuations. A prolonged thaw can start the process of the plant coming out of dormancy. Such grapes can die even at a temperature that is much higher than the critical one.
Influence of the climate of the Volga region on the method of sheltering grapes
An important condition for successful wintering is the correspondence between the method of shelter and the climatic conditions in which the grapes grow. The following indicators must be taken into account:
- record low temperatures for the area in winter;
- the presence and height of snow cover;
- wind direction and strength;
- frequency and duration of thaws.
The Volga region is a large region, its climate in different areas is very different. But in general, it is characterized by rather cold winters with average temperatures ranging from -10 to -15 degrees. At the same time, the temperature minimum in some areas exceeds -40 degrees. And this is with a small height of snow cover.
How to cover grapes for the winter in the Volga region? To do this is not so difficult.
Success can be achieved if the following conditions are met:
- properly prepare the vines;
- choose the optimal time for sheltering grapes, depending on the weather;
- choose the best method of sheltering grapes in each specific case.
Preparing the vine for wintering
Oddly enough, it begins in the spring. Timely removed shelter will save the plants from spring return frosts, thereby allowing the grapes to retain all their strength for flowering, crop formation and vine ripening. Agricultural practices carried out on time and in full also contribute to this.
Too much load on the bush can significantly weaken the vine.
One of the conditions for successful overwintering is the complete maturation of the vine. No matter how unripe shoots of grapes are covered, it will not be possible to save them in winter. Therefore, you need to take care of this in advance. There are varieties of grapes in which by autumn all the shoots ripen completely even without the participation of the grower. The rest will have to be taken care of and all the green shoots will be pinched back in August in order to achieve their full maturation before frost.
There are a number of important activities that must be carried out even before the onset of frost:
- dry land freezes much more strongly, therefore, moisture-charging watering of grapes in autumn is required, the earth should get wet to the entire depth of its roots;
- top dressing with potassium-phosphorus fertilizers in September will make the bushes more frost-resistant, allow the vines to ripen faster;
- after leaf fall, cut out all unripened shoots, in accordance with the rules for forming a bush;
be sure to leave 2-3 spare buds on each shoot, pruning only at positive temperatures, otherwise the vine becomes brittle and breaks easily. Bushes of the first year are not pruned.
- treat grapes with antifungal drugs, for example, copper sulfate according to the instructions;
- remove the vines from the trellises and tie them into loose bunches.
Covering material also requires preparation: it is disinfected, the worn-out one is thrown away and a new one is purchased.
The choice of terms for sheltering grapes
It is important to do it on time. If you cover the grape bushes earlier, the kidneys may die from decay or get sick with fungal diseases. In autumn, there is an active process of accumulating nutrients in the roots of grapes. They will help the plant withstand all winter hardships. Therefore, every day is important – you should not rush to shelter. In practice, the first frost on the soil serves as a signal for its beginning.
The weather is unpredictable, the uninsulated roots of the grapes will freeze before you cover them.
To successfully overwinter, the vine needs to go through natural hardening. Its initial stage falls on the period when the temperature is in the range from +10 to 0 degrees. The final stage is for the period when the temperature is kept in the range from 0 to -5 degrees. The duration of each is at least a week. The transition to new conditions of existence should take place gradually so as not to cause stress in plants. This is another reason not to cover the vines ahead of time.
How to cover grapes
There are many ways to hide. Let’s try to figure out which one is most suitable for the Volga region. Sufficiently severe natural conditions do not allow the use of partial measures. The vines require only full cover.
No matter how you are going to cover the grapes, you need to start this process from the root zone, since it is most sensitive to the action of sub-zero temperatures.
A dead root system cannot be restored. Such a bush is lost forever.
In order for the roots of the grapes to be comfortable in winter, it is necessary to cover the root zone with a diameter of at least 50 cm with a layer of earth, and preferably with humus, at least 20 cm high. The hilling method is not suitable for this. We will have to take the land from other beds, on which there were no plants affected by fungal diseases.
It is especially important to insulate the roots of grapes on sandy and sandy soils, as they freeze through more. To prevent this from happening, sheets of cardboard are additionally laid around the bushes or the ground is sprinkled with a layer of coniferous litter.
Shelter for the grape bush itself must meet the following criteria:
- protect from frost;
- prevent the accumulation of moisture;
- smooth out temperature fluctuations;
- do not allow rodents to damage the bushes;
- protect from sunburn in early spring.
Sometimes the reason for the death of grapes is not severe frosts, but the aging of the eyes due to high humidity. Therefore, the shelter must be dry and provide air circulation at temperatures close to 0. The following scheme is best suited:
- connected vines are laid on boards laid under a bush, plastic trimmings can be used, the main thing is that the substrate is dry;
- fall asleep with dry sawdust or dry leaves treated for fungus.
Take care of poison from rodents and means that repel them. Elderberry branches and a small container with diesel fuel poured into it, a special poison bought in a store, will do.
- they put low arcs and cover it with a film on top, which is well pressed so that it is not blown away by the wind, the gap between the sawdust and the film should be about 10 cm, and air should be left along its edges. With the onset of winter, everything will be covered with snow, and as long as there are no severe frosts, air will enter the vents, preventing the grapes from aging. Instead of a film, you can use cut sugar bags.
Possessing the effect of a membrane, they release moisture to the outside, but do not allow it to penetrate inside.
Some growers use film prepared as follows. Buy it in the form of a sleeve. Cut into pieces of the required length, stratify them and put pieces of cardboard between the layers.
Reed mats have proven themselves well. They keep warm well. Their only drawback is their fragility.
You can do the following in the vineyard:
- carry out all preparatory activities as usual;
- lay the connected vines on a dry lining of boards or plastic, fasten with hooks;
- cover with white covering material, folded in half so that it lies in a loose layer. White color protects the bushes from burns, and a loose layer of spunbond maintains a constant temperature;
- put low arcs and throw a film on them so that there are small air gaps, the distance between the film and the spandbond is not more than 10 cm;
Many growers for shelter simply dig in the bushes with earth completely. This often gives good results. But if there is a possibility of stagnant water on the site, it is very possible for the vines to rot during the snowmelt period.
Each vine grower chooses to shelter the method that is most suitable for his site and the grape varieties that are planted on it. Most of the time, experience comes with time. You just need to carefully observe and draw the right conclusions from your observations.