With the advent of spring, gardeners rush to start growing early vegetables. One of the most popular spring crops is cucumber. In this article, we will consider what temperature regime is needed for cucumber beds at the stage of sowing, seedling growth, flowering and fruiting, and also when you need to cover cucumbers.

The basic principles of temperature

Cucumber is a tropical plant and needs a sufficiently high temperature of air and soil for normal growth and development. The thermal optimum of growth depends primarily on the light intensity and phase of plant development, the temperature range is quite wide and amounts to +18 ... + 35 ° C.

Cucumber is very demanding on the thermal regime. Ensuring the correct temperature is of great importance, because, unlike the aerial part of the cucumber, its root is not able to regulate its heat. The optimum temperature of the substrate for growing cucumber is in the range +22 ... + 25 ° C, it should be relatively constant and show the lowest daily fluctuations.The lower temperature of the substrate prevents the growth and activity of the roots, and therefore, the absorption of moisture and minerals, especially phosphorus. This can cause the ovary to die and the plants to wilt. Reducing the heat of the substrate in the root zone to +10 ... + 15 ° C violates the biochemical processes that determine the growth of the underground and aboveground parts of the cucumber. At lower soil temperature, the root system of the cucumber can also be infected with root rot (Pythium debaryanum). The minimum thermal minimum of the soil is considered to be + 13 ° C, and the maximum - + 35 ° C.

Cucumber is a plant that is very sensitive to too large changes in the thermal regime, especially between day and night. Fluctuations should not exceed 6-8 degrees. The minimum temperature minimum for a cucumber is considered to be + 12 ° C, but plants begin to respond already to a drop in heat below + 20 ° C, young cucumbers are especially sensitive to cold.

Did you know? Eating cucumbers can reduce the risk of developing certain types of cancer. It is believed that the ingredients in the vegetable can reduce the risk of cancer of the breast, ovary, colon and prostate gland.

Optimum temperature conditions for the growth of cucumbers

At different stages of growth, a cucumber requires different indicators of heat of air and soil, since each of these indicators affects certain characteristics. Under the influence of temperature, the plant can: stop growing, grow too fast or get bitterness in the fruits.

During sowing

Cucumber is very sensitive to cold, so it is sown at a time when the risk of return frosts no longer arises. In the southern, western and central parts of the country, cucumbers are sown in open ground when the temperature exceeds + 18 ° C, usually in the first decade of May. In the northern regions, sowing is carried out at the end of May.

When growing seedlings

At the seedling stage (with low light intensity and a short day), a relatively low thermal regime is suitable, in the range +20 ... + 25 ° C. Higher thermometer readings during this period lead to the fact that the plants are stretched, their stems are painfully thinning.

A long stay of cucumber seedlings at + 12 ° C can lead to their death. The optimum air temperature during germination is about + 30 ° C, the minimum soil heat is permissible up to + 14 ° C, but the seeds germinate in cold earth for a very long time.

Important! Under good conditions (at a temperature of + 20 ° C and above), cucumber seeds germinate after 3-5 days. Cold soil and lack of moisture significantly slow the emergence of seedlings.

In the active phase of growth

Liana growth can be strongly influenced by maintaining a higher temperature at night than during the day. Greenhouses actively use this property. Cool nights increase yields, but delay fruit ripening. On the other hand, a warm environment accelerates the ripening of cucumbers, while at the same time accelerates the aging of plants, which reduces the overall yield of fruits.Damage to plants can also occur at a much later period, when cucumbers are already well developed. This is possible if after a hot period in the street it gets colder up to +4 ... + 6 ° C.

During fruiting

Adult plants in the flowering and fruiting phase require temperatures close to + 30 ° C. Heat above + 35 ° C has a very adverse effect on plants, since the thermal maximum of the cucumber is + 40 ° C. At the same time, a short-term temperature increase, even up to +35 ... + 40 ° C, at a very high humidity of 95–100%, has no negative effects. However, if the heat lasts longer, especially at lower air humidity, it can cause the ovary to fall and the cucumber lashes to wilt.

Important! Large daily temperature amplitudes prevent the growth of plants, cause deformation of the fetus and are the main cause of bitterness in them.

Features of temperature when growing cucumbers

The vegetable grower needs to know at what temperature the cucumber plantation feels comfortable, and can normally continue growing and developing lashes, flowering or fruit setting, and what temperature is critical, and urgent measures need to be taken: cover the plantings from frost with agrofibre (spunbond) or take measures to reduce heat in the greenhouse.

In the open ground

The optimum temperature for the growth of cucumbers in the open field is in the range +20 ... + 25 ° C. For a cucumber, proper soil temperature is more important than air heat. If the earth is warm, plants can withstand air cooling to + 10 ° C, although in this case there is always a risk of developing leaf chlorosis.

Cucumber grows better in places protected from the wind. Strong winds in combination with heat can lead to poor fruit and mechanical damage to the skin. As a protection against wind, cucumber beds are surrounded by tall crops sown in advance (corn, sorghum) playing the role of wind-shelter wings.

In the greenhouse

As mentioned above, the optimum growth temperature for adult cucumbers is + 30 ° C simultaneously with very high humidity (up to 90%). But thanks to the transparent coating of the walls and ceiling of the greenhouse for ultraviolet rays, the air in these structures heats up very quickly during the day and needs to be cooled.

In small greenhouses, large vents are provided for this under the ceiling and near the floor, opening which the vegetable grower creates a draft. In small greenhouses there is enough door and a window located on the opposite wall, under the ceiling.There is also a classic way to quickly remove the heat inside the greenhouse - to whiten the roof and walls on the south side of the building with a solution of water with lime. In large industrial greenhouses, fans are installed that force the heated air masses.

Did you know? Cucumber is extremely rich in vitamin B, minerals and electrolytes, these properties make it one of the best remedies for getting rid of a headache. Eating this vegetable will alleviate the problem of a morning hangover after an evening alcohol abuse - you only need to eat a cucumber before going to bed.

At what temperature do cucumbers stop growing

Vegetable growers know that cucumbers instantly die at sub-zero temperatures, but not all the plus readings of a thermometer are suitable for the growth of tropical vegetables.

Undesirable temperatures:

• cucumber plantings are afraid of lowering below + 15 ° C, after which they are somewhat suspended in growth;
• plants withstand a short-term decrease to +10 degrees, but at the same time their growth is completely stopped;
• at + 8 ° C and lower - cucumbers do not grow absolutely, their root system rots, which leads to death.

Even returning an acceptable temperature will not help those affected by the cold, but the surviving plants — their growth and yield will differ for the worse from cucumbers that constantly grow in warmth.

At what temperature do you need to cover the cucumbers

Sometimes it happens that cucumbers already have three or four full leaves, and suddenly a cold snap (below + 10 ° C), or even night frosts comes. In this case, the grower urgently needs to cover the plants, and take measures to save them.

In the greenhouse:

1. Close all ventilation openings.
2. Before frost, pour plenty of flower beds with cucumbers, but make it so that the water does not get on the plants, but only moistens the soil.
3. Cover the beds with cucumbers with lutrasil (agrofibre, spanbond or other non-woven material), if the amount of covering material allows, make a double coating layer.
4. If there is a heating system, to drain the greenhouse, if this is not possible, put an electric heater inside or place containers with hot water (buckets, barrels), if there is no way to heat in the greenhouse, on a bed of cucumbers, on top of agrofibre, throw a plastic film.

Important! Water has a good heat capacity, which is why before approaching minus temperatures it is necessary to water the soil in which cucumbers or tomatoes grow. Wet soil generates heat, which is enough to create a thermal cordon at a height of 15 cm from the ground.

1. If frost is expected - the bed is watered well, with a strong drop in temperature without the expected frost - watering the soil is not necessary.
2. Plants are covered with any non-woven material, in several layers.
3. Across the beds, with a distance of 50 cm from each other, arcs of wire or tree branches with good flexibility (willow, birch) are installed, on top of which a plastic film is laid.
4. Before sunset, under the shelter of the garden, you can place two-liter bottles of hot water (under agrofibre, next to each cucumber).
5. At night, hay or any old rags are thrown over the polyethylene tunnel in order to make the polyethylene impenetrable to light. If frost or low temperature lasts several days - hay (rags) are not removed, the plants are left without access to light, in the dark. Vegetable growers have long been tested in practice, if cucumbers are closed from the light in the cold, they become pale, frail, but survive and quickly return to normal after the cold.

Danger of high and low temperatures

In the summertime in greenhouses, the thermometer column in the middle of the day can reach +50 ... + 60 ° C. At this temperature, the cucumber stalks simply “weld”, moreover, even at a heat of + 35 ° C, the plants freeze in growth, their pollen becomes sterile, their ovaries turn yellow and fall. That is why when building a greenhouse for cucumbers, it is necessary to carefully consider the ventilation system.

Low temperatures (below + 10 ° C) are dangerous for the inhabitants of the tropics, and can cause: shedding flowers from the ovaries, stunting, the development of fungal diseases and even death of the plant. The vegetable grower needs to remember that even the temperature of + 15 ° C is too cold for the normal growth and development of cucumbers.

Did you know? The tonic properties of cucumber are used in cosmetology for the manufacture of lotions and creams. For the skin of the face and neck, a mask from the slices of this fresh vegetable is also very useful.

Thermal conditions are important for the successful cultivation of cucumbers. Therefore, gardeners need to provide the plants with the temperature that they need at this stage of growth (with seedlings, growing seedlings, flowering or fruiting).