Optimal growing conditions for cucumbers and features of their cultivation techniques

Temperature regime, humidity, and cucumber nutrition system

Cucumber is extremely demanding regarding growing conditions; therefore, any deviations from the norm directly reduce its yield. For successful growing season, the crop requires a short day (10–12 hours), intense lighting, and strict adherence to the temperature regime. In shaded conditions, plants stretch, develop slowly, and fruit poorly.

• Optimal temperature for growing season — 22–28 °C
• Daylight length — 10–12 hours
• Air humidity — 80–90%
• Soil moisture — 65–95% of full water capacity
• Growth cessation threshold — 10.1% soil moisture

Cucumber is considered the most moisture-loving vegetable crop of all common ones. For example, while cabbage stops growing when soil moisture drops to 8.7%, cucumber stops developing at 10.1% of full water capacity. However, excess moisture is also dangerous: in waterlogged soil, air concentration drops, roots slow their growth, and can die off completely.

Root system of the cucumber is weak and does not penetrate deeper than 20 cm, so the crop is extremely sensitive to soil quality. Practitioners know: without manure, a cucumber bed will remain empty. Plants tolerate high doses of organic fertilizers well — from 4 to 20 kg per 1 m². As an alternative to manure, one can use rotted waste, leaves, peat, straw, or sawdust, but such compost must be enriched with nitrogen at a rate of 20 g of ammonium nitrate for every 5 kg of sawdust.

The highest efficiency is shown by localized application of organic matter into the beds. This creates a nutrient "pie" that gradually releases heat and carbon dioxide, stimulating root growth. To create such a substrate, several sequential actions are performed.

1. Dig a trench along the future bed where the row will be.
2. Place a layer of organic fertilizer 15–20 cm thick at the bottom.
3. Cover it with a layer of soil 12–15 cm thick.
4. Wait for 5–6 days, after which proceed to planting the plants.

In addition to organic matter, cucumbers require fractional mineral nutrition. The need for elements changes depending on the phase of the growing season, soil type, and climate. At the beginning of growth, the crop actively consumes nitrogen, while during budding and fruiting, potassium takes priority. On light sandy soils, the application rate of nitrogen fertilizers should be increased, and on floodplain soils — potassium fertilizers.

Preparation of seeds for sowing and resuscitation top dressing

A healthy start and resistance to unfavorable conditions are established at the stage of preparing seed material. For sowing, it is recommended to use seeds stored for 2–3 years. Immediately before sowing, they must be warmed at 50–55 °C for 2.5–3 hours to obtain uniform and fast emergence.

To protect future seedlings from pests and pathogens, seed treatment is applied. For this, they are kept for 12 hours in a cloth bag moistened with a special nutrient solution. Two compositions for soaking are most popular:

• Nutrient mixture with microelements: 1 teaspoon of nitrophoska, as well as copper sulfate and boric acid at the tip of a knife, dissolved in 1 l of hot water.
• Organic solution: 1 tablespoon each of dry cow manure and sifted wood ash per 1 l of hot water.

Natural antiseptics and biologically active substances are also used for disinfection. Pure aloe juice and a 2% hydrogen peroxide solution show high efficiency. Frozen potato juice gives good results: to obtain it, 2 kg of sprouted potato shoots are infused in 10 l of hot water for 48 hours, after which the working solution is diluted with clean water in a 1:4 ratio.

After disinfection, the seed is rinsed with water, placed between layers of damp gauze, and hardened at lower temperatures. During the hardening process, which lasts 5–7 days, the seed must be kept moist periodically. Temperature conditions are chosen depending on the cold resistance of the cultivar.

1. For cold-resistant cultivars: keep the seed for 48 hours at a temperature of 0–2 °С or harden using a variable cycle (6 hours at 18–20 °С and 18 hours at a temperature from 0 °С to -2 °С).
2. For other cultivars: perform hardening at a constant temperature of 0 °С.

Prolonged cold snaps paralyze the activity of the cucumber root system, causing the plants to stop absorbing mineral salts from the soil. As soon as warm weather sets in after a cold spell, an urgent root top dressing with ammonium nitrate must be carried out. The fertilizer is applied into furrows to a depth of 5–7 cm, followed by irrigation.

If the roots are still struggling, the plants are supported with foliar top dressing. This technique accelerates the onset of fruiting by 4–5 days and significantly increases the total harvest. For this, a balanced solution of macro- and micronutrients is sprayed over the leaves.

Seedlings cultivation and transplanting into soil

Cultivating cucumbers via transplants allows for early production and ensures high survival rates of plants in the greenhouse. For this, seeds are sown one by one into paper, plastic, peat, or peat-humus pots filled with a nutrient soil mixture. Immediately after sowing, the containers are covered with a damp cloth to prevent the soil from drying out before the emergence of the first seedlings.

The temperature regime during the germination stage is critically important for the formation of healthy seedlings. Until emergence, the room temperature is maintained at 25–28 °C, and it is lowered immediately after germination to prevent the seedlings from stretching. For 3–5 days, 15–17 °C is maintained during the day, 12–14 °C at night, and on cloudy days the temperature is kept at 20–22 °C. In greenhouses, seedlings are watered once every 2–3 days; when grown in indoor conditions, they are watered daily in the mornings.

To obtain an extra-early harvest in plastic greenhouses, hotbeds are established. This involves using well-heated biofuel, which is laid in a layer 30 cm thick and 50 cm wide, then covered with soil mixture and fitted with an additional plastic cover. This technique allows for transplanting seedlings a month earlier compared to greenhouses relying solely on solar heating, where cucumbers are moved only after the spring frosts have ended.

• Seedling age — 30–35 days
• Planting density — 4–5 plants per 1 m²
• Planting scheme — 60 × 30 (40) cm
• Planting depth — 3/4 of the pot height
• Irrigation water temperature — 24–26 °C

Forming and pruning cucumber vines

Correct formation of the cucumber vine on a trellis directly affects bush illumination, ventilation of the plantings, and the final yield. Without timely pruning of shoots, the plants quickly become overcrowded, which provokes the development of diseases and reduces the quality of the cucumbers. Bush formation is carried out in stages as the main stem grows.

1. Perform "blind pruning" of the root zone. Completely remove all side shoots and flower buds from the leaf axils in the lower part of the stem at a height of up to 50 cm from the ground.
2. Pinch the lower tier shoots. In the next section of the stem (up to 1 m in height), pinch 4–5 side shoots, leaving only one leaf and one fruit set on each.
3. Form the middle and upper zones. Side shoots in the middle and upper parts of the main stem (at a height of 1 to 1.5–1.7 m) should be pinched at two leaves and two fruit sets. Shoots directly under the trellis should be pinched at three to four leaves and three to four fruit sets.
4. Adjust the second-order shoots. Completely remove second-order shoots in the lower part of the bush. In the middle part, leave one leaf and one fruit set on them, and near the trellis itself — two fruit sets.
5. Shape the stem top. After the tip of the main stem grows past the trellis, gently drape it over the wire, giving it one turn. Pinch the growing point after the fourth leaf and secure the stem with twine. Remove the shoot from the first axil behind the trellis, and distribute the three remaining ones evenly, pinching them every 50 cm while leaving a continuation shoot.

Fruiting regulation allows you to avoid overloading the plant and obtain standard produce. The optimal load on the main stem up to the trellis is from 4 to 6 fruit sets; at the same time, all female buds at a height of up to 1 m must be removed. In order not to weaken young plants, the first harvest is carried out when the fruits reach a mass of 200–250 g. Subsequently, marketable gherkins are harvested at a mass of 300–500 g.

Growing cucumbers in unheated greenhouses

For successful cucumber cultivation in unheated greenhouses, the correct selection of hybrids and cultivars is critical. The optimal choice is parthenocarpic hybrids that do not require pollination. If you are planting standard cultivars for open soil, it is necessary to ensure regular access for pollinating insects by ventilating the greenhouse daily. Transplants are planted in such greenhouses in the second half of May, having previously added loosening components to the soil to prevent soil compaction.

• Transplant planting date in greenhouses — May 15–20
• Transplant age for greenhouses — 28–30 days
• Transplant age for standard planting — 20–25 days
• Planting density (standard) — 2.2–3.3 plants/m²
• Planting density (ribbon) — 3.5–4.5 plants/m²

With a standard planting pattern, aisles are 120 cm wide, and the distance between plants in a row is from 25 to 40 cm. For sparse-foliage cultivars, it is more efficient to use a ribbon pattern. In this case, the distance between ribbons is set within 80–90 cm, between rows — 60–70 cm, and the spacing in the row is 30–40 cm. Since soil in greenhouses compacts quickly, it is mandatory to add loosening components to the soil mixture.

Special attention is paid to water and temperature regimes during the fruiting period. Before the start of the first harvests, a heavy irrigation is carried out at a rate of 3 to 7 liters of water with a temperature of 22–25 °C per square meter. Subsequently, soil moisture is maintained within 76–78% by irrigating the plantings every 1–2 days, and daily during hot periods. The air humidity in the greenhouse should be 80–85%. Irrigation should be ground-level, with a limited spray zone, so that water does not get onto the leaf blades.

Trellis system organization and harvesting

Growing cucumbers on vertical supports and trellises significantly reduces the risk of infection with downy mildew. Plants raised above the ground are better ventilated, and significantly less droplet moisture condenses on their leaves. Tying up begins just 2–3 days after planting the transplants. The supporting wire is tensioned at a height of no more than 1.8 meters, which makes subsequent plant care as convenient as possible.

1. Tension the supporting wire above the planting rows at a height of 170–200 cm.
2. Tie one end of the twine to the wire with a sliding knot.
3. Secure the lower end of the twine to the plant stem at a height of 10–12 cm from the soil level.
4. As the stem grows, regularly wind it around the tensioned twine.

In modern greenhouse farms, growing cucumbers on a vertical net, which the plant clings to independently, is popular. In small structures, net sheets can be tensioned at an angle in the shape of a tent. Such a design guarantees uniform illumination of the leaves and facilitates the harvesting of fruits that hang freely downwards. When working in a "tent," damage to vines and leaves is excluded, which directly increases the overall productivity of the crop.

To create vertical supports, alternative rigid structures are used instead of classic twine. Strips with a width of one cell and a length of 1–2 meters are cut from galvanized mesh with 1.5x1.5 or 2x2 cm cells. Spirals made of 3 mm galvanized wire with a length of 1–1.5 meters with loops every 10–15 cm, made by winding onto a 1.5 cm pipe, are also used. Finally, supports are made of brass strips 1 mm thick and 5 cm wide with free space inside, or light metal chains are used.

All types of rigid supports are fixed to the supporting cable with metal hooks or strong rope. When growing in greenhouses, the cable is additionally fastened to the roof structure elements for reliability. During the growing season, be sure to remove tendrils while simultaneously shaping the plant and pinch the shoots according to cultivar recommendations. Gherkins on vertical trellises are harvested every 1–2 days, preventing them from becoming coarse.

= и‘. ^ 72,. й х 4 7. и ``. 5 хх Сетка 4 А 22 № #\ 7-74 “Айа (о Пу. мил С <. а Ё а ка к | С =] [] Methods of vertical cucumber cultivation: а — on netting; б — on metal mesh; в — loop; г — "curls"; д — expanded metal mesh; е — hooks of cucumbers leads to slow growth of fruit set, their shedding, and ultimately to a reduction in yield. Growing cucumbers in hotbeds requires specific technology. The hotbed is filled with well-warmed biofuel and compacted. After 3—4 days, the biofuel settles, and it is compacted further. A furrow 10—12 cm deep and 20—25 cm wide is made in the biofuel and filled with soil mixture so that the layer of soil mixture in the furrow is at least 23—25 cm, and 10—12 cm above the biofuel. The soil is leveled and holes 10—12 cm deep are made; they are watered and transplants are planted at a rate of 3—4 to 5—8 plants per 1 m².

The temperature maintained in the hotbed is: daytime — 25—27 °C, nighttime — 16—18 °C. Plants are watered with warm water — moderately before flowering (4—6 liters of water per 1 m²) every 3—4 days; during the fruiting period, they are watered every other day with double the water consumption rate. On sunny days, from 11 to 12 o'clock, watering is performed and the hotbed is closed, as a result of which the air becomes saturated with water vapor. High temperature (26—30 °C) and humidity (95—100%) promote intensive growth of leaves, shoots, and the formation of female flowers. Overheating above 30 °C is undesirable, so hotbeds are opened slightly after one or two hours of the "steam bath" procedure.

Top dressing of plants in hotbeds is carried out several times. The first top dressing is done 10—14 days after planting with a solution of 15—20 g of nitroammophoska in 10 liters of water; the second and subsequent top dressings are done every 10—14 days, alternating mineral and organic fertilizers. 10 g of superphosphate per 10 liters of solution is added to the organic top dressing (mullein 1:6 or poultry manure 1:15). In case of stunted plant growth, they are fed with a urea solution (15 g per 10 liters of water). Micronutrient fertilizers can be added to the liquid top dressing. After long periods of overcast weather, foliar feeding with a urea solution (10 g per 10 liters of water) is carried out.

Cucumbers grown in a hotbed are guided toward the longitudinal sides of the hotbed as their shoots grow and are pinched to the soil.

Cucumbers are harvested regularly. They are picked by gently turning the fruits together with the stalk and detaching them from the shoot with a finger press. Shoots should not be lifted or turned over during harvesting.

Growing cucumbers on insulated soil should be done in a well-lit area protected from cold northern winds. The best predecessors for cucumbers in this case are tomatoes, cabbage, and peas.

In the spring, 10—15 kg of fresh manure or humus per 1 m² is applied to the plantation. Before planting, during digging, 40 g of nitroammophoska or 15—20 g of superphosphate and 10—20 g of urea and potassium sulfate are applied.

Only well-hardened transplants are planted once the danger of frost has passed. To avoid losses from damage to the transplants, one can use earlier planting combined with simultaneous sowing of sprouted and dry seeds. In case of seedling death due to frost, the seeds will provide emergence. If conditions are favorable, excess plants are removed. The distance between plants should be 10—15 cm.

Caring for cucumbers on insulated soil consists of loosening, irrigation, ventilation, and top dressing. Loosen the soil shallowly so as not to damage the root system. Ventilate by lifting the film cover, which is raised for the entire day when warm weather sets in. Plants are watered as needed. Top dressing is carried out in the same way as in hotbeds.

What destroys cucumbers? The number one enemy of the cucumber is the spider mite. Control measures must be ruthless — in the autumn, it is necessary to dig up the soil and disinfect greenhouses. If mites appear, plants are sprayed with infusions and decoctions of chamomile, potato, onion, garlic, and common yarrow.

Downy mildew. It is easy to recognize — yellow-green spots form on the upper side of the leaves, and a gray-violet bloom (mycelium) forms on the lower side. The spots gradually merge, and the leaves fall off. Downy mildew develops on cucumbers in wet years and progresses rapidly at a temperature of 19—23 °C. The pathogen persists on the remains of diseased leaves in the form of spores. They are hardy and retain their harmfulness for 6 years. In moist soil, the spores germinate, and infection of seedlings occurs.

You can protect against downy mildew by choosing resistant cultivars.

In greenhouses, sharp temperature fluctuations and high humidity should be avoided. It is necessary to carry out spraying with a 0.4% copper oxychloride solution or 1% Bordeaux mixture.

Powdery mildew. At first, small round spots covered with a white powdery coating form on the upper side of the leaf, and then on the lower side. Subsequently, they merge, covering the entire surface of the leaf. Diseased leaves fall off. The infection also persists on weeds: plantain, sow thistle, etc. It develops most vigorously if there is droplet moisture. Against powdery mildew, plants are treated with fungicides (70-80% colloidal sulfur — 40 g per 10 l of water in a greenhouse and 20 g per 10 l in open soil; 10% isofen — 60 g per 10 l of water). Infusions of cow manure or decomposed hay work well: 1 kg is poured into 3 l of water, left for three days, strained, diluted 3 times, and the plants are treated once a week.