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Video: How To Extend The Season For Receiving Strawberries In The Country
The use of covering materials and film covers
Fragrant strawberries - for the whole summer
With standard cultivation of strawberries in the North-West, we get fresh berries only from the third decade of June to the end of August. In order to extend the period of obtaining fresh berries, several simple techniques and methods are used.
Here are some of them:
- select varieties with different ripening periods (early, middle, late);
- they grow remontant varieties that allow you to harvest in the autumn;
- accelerate or retard the vegetation of plants using various agrotechnical methods of obtaining a crop at a given time.
Usually, gardeners try to get an earlier harvest using these methods, since the price of strawberries during this period is higher.
In the open field in winters with high snow cover, you can accelerate the melting of snow by scattering ash, dried humus, bark compost or peat over the snowdrifts at the end of winter. On sunny days in such places, the snow melts a few days earlier, which, with a favorable spring, can accelerate the start of growth of strawberry plants. However, it is necessary to take into account the risk of damage to plants on bare ground by strong nighttime spring frosts. This also increases the protrusion of plants from the frozen soil. Therefore, it is necessary to take measures to protect plantations from severe night frosts, if there is a possibility of their occurrence at certain periods.
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The use of covering materials
A fairly common way to accelerate the ripening of strawberries in the open field is to cover the strawberry plants with commercially available non-woven material - lutrasil, spandbond and perforated film, which overshadowed many other ways to get an earlier harvest.
The effect of these covering materials on accelerating the ripening of the crop is approximately 5-7 days. Covering materials are also of great importance in protecting plants from frost and pests.
The method of accelerated harvesting of strawberries is based on the fact that under the shelter the temperature rises: its average daily value is 1 … 3 ° C higher than in the open field, therefore, plant growth in spring begins earlier. The greatest benefit in accelerating fruiting is obtained when the shelters are spread immediately after the snow melts, that is, usually already in April. On plantings of strawberries at the beginning of flowering, it is recommended to remove the shelter in the daytime and cover the bushes again if the threat of frost return is expected.
Various methods are used to secure both lutrasil and apertured films. Often it is enough to fix them along the edges, but on wide strips it is necessary to fix the middle parts of the shelter so that the wind does not raise it too much. A fairly common and best way to secure the lutrasil without the danger of breaking the edges of the shelter is with bricks or plastic bags filled with sand. Ordinary stones are bad because they easily roll off the edges of the shelter. Many gardeners use metal staples, placing them about every couple of meters. The floors of the covering material must be folded so that they do not break.
The effect of the covering material can be enhanced by spreading it over the landings in two layers. But we must remember that the costs will increase and the risk of overheating of plants may increase. Under a double shelter, the average air temperature is about 2 ° C higher than under a single-layer one. When using it, the second layer must be removed when the soil temperature rises to 10 … 12 ° C, otherwise there is a risk of damage to plants. In addition, there is an increased risk of rot under double cover, as the humidity in the air increases and the ventilation decreases. Usually preference is given to a double coating of lutrasil and perforated film: the lutrasil is at the bottom and the film is at the top.
There are many covering materials on the market now. They are usually made from polypropylene. Non-woven fabric allows moisture and air to pass through. The density of the fabric is such that the temperature does not rise too high even in sunny weather. The width of the material is different, the term of use is three years, depending on the quality and strength. When using lutrasil to protect against frost, it is spread on the day before freezing so that heat can accumulate under it. For the same reason, plants should be well watered throughout the day. If you have a sprinkler, you can irrigate with lutrasil over a large area.
Perforated transparent film is cheaper than lutrasil. Round holes with a diameter of about a centimeter are made on it, through which water spills inside under the film and does not allow the temperature to rise too much. For strawberries, film with 500 holes per square meter is suitable. The properties of perforated film are identical to lutrasil, but there are some differences: it protects against frost worse, it is heavier than lutrasil, although it is more durable.
In addition to covering materials used for surface cover of plants, film materials are widely used to cover the soil in the beds. Holes are cut on the film, into which the seedlings are planted. Such materials include black polyethylene or PVC film, film fabrics, special films of brown or greenish-gray tones, and others. These materials help protect plantations from weeds, retain moisture and warmth in the soil, keep berries clean and ripen earlier.
The black film has a thickness of 0.04-0.05 mm; when the soil is covered with such a film, the strawberry harvest ripens 5-7 days earlier. A high-quality film stays on the beds for the entire period of strawberry rotation, i.e. 3-5 years.
Film fabrics are so-called strawberry fabrics, made from narrow film strips, so they allow water and air to pass through, but do not let weeds through them. Their effect on the acceleration of maturation is the same as that of a black film. The film fabric material is so strong that it can be used on several turns of strawberries. Film fabrics are very popular in Finland among amateur gardeners, but in commercial production, the high cost of the material is often an obstacle to its use.
Special films used on strawberry ridges are distinguished by the fact that they let some of the sun's rays pass through themselves, while warming the soil faster than when using black film. The technology for these usually brown or greenish-gray films is the same as for black film. The difference in getting an earlier crop compared to black film is very small - 1-2 days.
In small volumes, experiments were carried out on the use of biodegradable film in the cultivation of strawberries. The results showed that the advantage is that it does not need to be removed at the same time as removing the plants. At the same time, the rapid breakdown of the film allows weeds to grow, taking up free space.
The use of film shelters
Particularly widespread are various types of small-sized film shelters - tunnels, under which the berry ripens 7-12 days earlier and the yield of plants increases significantly (by 70-80%). Small-sized small tunnels are 50-80 cm wide and 40-50 cm high. They cover one row or one two-line ribbon of strawberries 10-20 meters long. Medium tunnels can cover two rows or two two-line tapes. Their width is 110-130 cm, height - 80-90 cm. Their structure is similar to the device of small tunnels. The berries ripen in them almost simultaneously.
In some years with cold autumn, the film tunnels can also be used to shelter plants of remontant and semi-renovated varieties, in order to give the opportunity to ripen all the berries during autumn fruiting.
As small-sized film shelters, you can use collapsible greenhouses (they are commercially available complete with plastic wrap) or wire arcs onto which the film is pulled (fasten the film from above with the same arcs), as well as other frame designs.
The most effective is the combination of small-sized film shelters with mulching plants with black plastic wrap. To do this, strawberries are planted on ridges 15 cm high and 100 cm wide at the base. Rolls of mulching film are rolled out over the surface of leveled ridges. The ends of the film at the ends and along the ridges are embedded in the soil to a depth of 10 cm. The width of the ridges covered with the film is 80 cm, the distance between the ridges is 50-70 cm. Strawberry seedlings are planted in cruciform or rounded holes made on the spread film. The diameter of the holes is up to 10 cm. Plants are placed in two lines with a distance of 30-40 cm between them, between plants in a row - 20-30 cm. 20-25 cm remains to the edge of the beds, which is quite enough for placing leaves and peduncles.
Wire frames on ridges covered with film are made slightly larger. The distance between the ends of the installed frames at the base is 100 cm, the height in the center is 80 cm. After covering them with a transparent film, the work of caring for plants consists mainly in removing weeds and growing whiskers that have appeared in nests, in ventilating tunnels on hot sunny days, in the fight with pests and diseases, in fertilizing and watering, if necessary. Under the influence of mulching the ridges with a dark film, the number of weeds, the degree of damage to berries by gray rot decreases, the temperature regime of the soil and the quality of products improve. When using film tunnels, the passage of all phenophases of plant development is accelerated by 10-25 days.
With all types of film shelters, the following points must be considered:
- at first it is necessary to monitor the tightness of the shelter, and when warm weather sets in, the air temperature, which should not exceed 20 … 30 ° C;
- during the flowering period of plants, to ensure their pollination, the film should be lifted from the sides if the outside air temperature is not lower than 5 ° С;
- during the formation of berries, the film is not opened, and when they ripen, they must be removed.
When the tunnels are covered with a perforated (perforated) film, the need to ventilate the structures is eliminated in order to avoid overheating of plants on sunny days and the removal of the film during strawberry flowering. For bees to freely penetrate under the film, the diameter of the holes must be at least 26-27 mm. Under the perforated film, the soil warms up much faster, the illumination of the tunnels increases, the relative humidity of the air decreases, the ripening of berries is accelerated by 10 days and the productivity of plants increases. You can water the plantings directly on the shelter. Film covers give the greatest effect on early varieties of the first and second years of fruiting.
To obtain earlier products (for 20-30 days or more), large-sized film shelters are used - stationary film greenhouses.
However, a high yield in film greenhouses is possible only with intensive use of the usable area (joint cultivation of strawberries with other crops), with early planting and the use of high-yielding, large-fruited varieties with sufficiently transportable berries of good taste, resistant to fungal and viral diseases.
It is possible to extend the ripening period of strawberries not only by accelerating the vegetation of plants, but, on the contrary, by delaying it in order to get a later harvest.
For this, the following methods are usually used:
- growing varieties with late ripening of berries;
- cultivation of remontant varieties that give an autumn harvest;
- spread a thick layer of straw on top of the plants.
In the latter case, to delay the ripening of the crop, a layer of straw is spread at the end of winter, when the amount of snow has decreased, but the soil is still frozen. In this case, the straw must be removed from the plants in early summer so that gray rot does not damage the planting. This technique of delaying the ripening of the crop in small areas is recommended by Finnish experts.