Technology for growing and planting cucumber seedlings in protected soil

Top dressing with carbon dioxide to reach a concentration of 0.2% is effective. The optimal air humidity is 80—85%, and the substrate moisture is 75—80% of field capacity. Optimal temperature of the irrigation water is 22—25 °C.

Ready-to-plant transplants should have at least 5—6 leaves. Only robust, healthy plants are planted. The number of pollinator-cultivar transplants, accounting for 10% of the total volume, should be 5—7 days older than the main hybrid transplants. This is necessary to ensure the appearance of male flowers by the time the female flowers bloom.

Planting transplants. Based on light conditions, the optimal planting time for bee-pollinated hybrids in the Polissia and forest-steppe zones is the first ten days of January, and in the steppe zone — the third ten days of December. Before planting, the greenhouse area is marked out, holes are made according to the size of the pots, and the soil is watered. In block greenhouses, plant rows are placed along the ridges, and parthenocarpic cultivars are planted in four rows with a bay width of 6.4 m and a row spacing of 160 cm. The distance between plants in rows for long-fruited hybrids is 40—45 cm 25 >

and for short-fruited ones — 30—35 cm. In span greenhouses, as a rule, the same number of plants are placed perpendicular to the central path. Bee-pollinated hybrids are planted in block greenhouses according to a 120 x (25—30 cm) scheme, i.e., 2.8—3.3 plants per 1 m² depending on the vigor of the hybrid. In span greenhouses, two planting schemes are used: (80+60) x 35—40 cm (3.6—4.0 plants) or 100 x 35 cm (2.9 plants). To reduce the likelihood of root rot infection, the root collar is not covered with soil. It is not recommended to compress the soil around the pot too much, so as not to injure the root system. If the transplants are overgrown, they are planted at an angle, directing all plants in one direction, and the lower part of the stem is lightly covered with soil to encourage the formation of adventitious roots.

Long-fruited parthenocarpic cucumbers are trained slightly differently. From the lower nodes of the main stem at a height of 50—60 cm, all female flowers and lateral shoots are removed at the beginning of their formation. Lateral shoots above 60 cm are pinched above the 1st—2nd or 3rd—4th leaf as they grow toward the trellis, while the last 2—3 shoots are draped over the trellis and pinched at a height of 0.7—0.8 m from the soil surface. The main stem is pinched 15—20 cm above the trellis wire and tied along the wire. Secondary lateral shoots are pinched above the first leaf in the middle tier and above the second in the upper tier. Lateral shoots are removed from the leaf axils of the main stem where fruit is setting. The optimal load on the main stem up to the trellis: up to 6 fruits for long-fruited hybrids, up to 10 for female-flowering type hybrids, and up to 14—16 for short-fruited hybrids (due to the double fruit set of the upper leaves).

All work must be done in a timely manner, as delays in pinching, removing shoots, and excess fruit set lead to weakening of the plants and a decrease in harvest. Greenhouse workers even have a term for this — "rolling off" lateral shoots, i.e., removing them while in the primordial state.

For pollination, beehives are placed in the greenhouses (one hive per 500—1000 m²). After planting the transplants in their permanent place, the following regime is maintained: air temperature on a clear day is 23—25 °C, on a cloudy day — 20—22 °C, at night — 18—20 °C; soil temperature — 21—23 °C; air humidity — 80—90%, soil moisture — 70—80% until fruiting, and 90% of field capacity during the fruiting period. As light intensity increases, the optimal daytime temperature values increase by 2 °C for every 10,000 lux. By changing the night temperature, one can regulate the growth and development of the plants. A temperature of 17—18 °C promotes fruit set and enhances the growth of vegetative mass, but fruit expansion slows down during this time. A night temperature of 19—20 °C ensures rapid fruit sizing. It follows that the night temperature regime should vary depending on the condition of the plants. To enhance the growth of lateral shoots and the formation of fruit sets, the temperature should be 17—18 °C for 7—10 days, and for faster fruit sizing, it is increased to 19—20 °C. Such a pulsating regime is especially important during cloudy weather. If the weather is sunny and good lateral shoot growth is observed, the night temperature is maintained at 18—20 °C.

Parthenocarpic hybrids are less demanding regarding light and temperature than bee-pollinated ones; therefore, they can be planted 10—15 days earlier, and the temperature can be kept 1—2 °C lower.

Carbon dioxide is supplied to the greenhouses in the morning hours and 2—3 hours before sunset, bringing its concentration to 0.15—0.20%. Root and foliar top dressing of plants with mineral fertilizers are carried out regularly, according to the data of agrochemical analysis.

Harvesting. Fruiting of cucumber begins 30—40 days after planting the transplants. Fruits are harvested regularly every one or two-three days, preventing overgrowth. As a rule, the first fruits are smaller in size than those in the second half of the fruiting period. The yield of fresh cucumbers is 25—30, and in the best cases — 30—32 kg per 1 m2.

Under high-tech conditions using low-volume hydroponics, drip irrigation, and computer-controlled microclimate, cucumber yields exceed 40 kg per 1 m2.

Specifics of growing cucumbers in the autumn crop Transplants are grown in greenhouses in the same way as for the winter-spring cycle, but without supplemental lighting. The duration of growing them under the high light conditions of July is reduced to 20—25 days. Transplants are planted in greenhouses in early August according to the pattern (100 + 60) x 30—40 cm for bee-pollinated varieties and 160x50 cm — for parthenocarpic hybrids. Special attention is paid to plant training so as not to allow excessive foliage and air stagnation, and to plant protection against diseases.

Plant training is basically the same as in the winter-spring period. Only the blinding of nodes is carried out up to a height of 90 cm. On the main stem, all fruits are left starting from a height of 40 cm. Lateral shoots are mainly trained to one leaf and one fruit set.

Air and soil temperatures are gradually lowered by 1—2 °C each month. In mid-October — November, it should not exceed 21—22 °C in clear weather, 19—20 °C in cloudy weather, and 17—18 °C at night. Irrigation is carried out mainly on clear days, in the morning, taking care that moisture droplets do not remain on the plant for a long time. Careful monitoring is kept for the timely removal of shoots that have finished fruiting, as well as diseased and dry leaves. Under favorable phytosanitary conditions, the yield of fresh cucumbers reaches 10—12 kg per 1 m2.

Cucumber crop in plastic spring greenhouses

Operating greenhouses in winter is a serious matter and is only feasible when the necessary conditions — temperature, humidity, and light — can be created in accordance with the biological requirements of the cucumber. If this is not done and the transplants are planted too early, the plants will be diseased and produce a low harvest. It is much easier to operate spring greenhouses when the Lord God himself helps — when the sun is shining. At the same time, from the point of view of learning about greenhouse cucumber culture, the technology for growing cucumbers in winter greenhouses described above is useful even for those who will grow cucumbers in spring greenhouses.

Growing transplants Cucumber seeds for growing transplants are sown 25—40 days before planting. The earlier the term of transplant planting, the older the age. Before sowing, to activate enzymatic activity, calibrated and treated seeds are soaked for 12—16 hours at a temperature of 20 °C in a fertilizer solution (per 1 liter of water, 10 g of superphosphate and potassium nitrate, and 0.2 g each of manganese, zinc, and copper sulfate). To accelerate emergence, seeds are pre-germinated. They are sown directly into pots measuring 10x10 cm to a depth of 1—1.5 cm.

Transplants are grown with moderate water supply and a relative humidity of 70—80%. Optimal soil temperature during the period from sowing to emergence is 26—28 °C. For the rest of the period — 23—24 °C. On sunny days, the air temperature should be 24—26 °C, on cloudy days — 20—22 °C, and at night — 18—20 °C. When growing transplants for unheated greenhouses, it is advisable to lower the night temperature by 1—2 °C and harden the seedlings. To do this, the temperature is lowered during the four days after their emergence to 20—22 °C during the day and 15—16 °C at night.

To prevent diseases such as olive spot, anthracnose, and bacteriosis, the transplants are sprayed 1—2 times with 1% Bordeaux mixture or 0.3% copper oxychloride.

Only fully developed, healthy plants are planted. Transplants of pollinator cultivars (Phoenix or Nezhinsky can be used as a pollinator cultivar) should be 5—7 days older than the transplants of the main hybrid. This is necessary to ensure the appearance of male flowers by the time the female flowers bloom.

Greenhouse preparation, transplant planting In spring greenhouses, cucumbers are grown in the actual soil with the addition of organic and mineral fertilizers. When preparing new greenhouses, 25—30 kg of manure, 45—60 g of superphosphate, and 20—30 g of potassium sulfate are applied per 1 m2 in the autumn. After this, the soil is dug up. In the spring, before loosening, 25—35 g of ammonium nitrate per 1 m2 is added. Every year, the hydro-physical properties of the soil are improved by adding loosening materials: straw chaff, sawdust, or peat — up to 25% by volume. When applying straw and sawdust, nitrogen fertilizers are additionally added in the spring to compensate for the nitrogen absorbed by the rapidly developing microflora, at a rate of 30 g of nitrate per 1 kg of sawdust or straw.

Transplants of short-fruited cucumber hybrids are planted in spring greenhouses when the soil at a depth of 10 cm reaches 14 °C at 8 a.m. In heated spring greenhouses, this usually occurs in the first or second half of March, depending on the heating capacity. In unheated greenhouses in the steppe zone, cucumber is generally planted in mid-April, and in the forest-steppe zone and Polissya — in the third ten days of April. These dates coincide with the transition of the average daily air temperature through 10 °C. Transplants of hybrids with elongated fruit shapes must not be planted in soil with a temperature below 10 °C. In cold soil, they develop a weak root system, and small leaves become susceptible to diseases. Inexperienced vegetable growers fall into another extreme, missing planting deadlines and planting in greenhouses in May at the same time as planting in the open ground. This leads to a loss of the early harvest. Remember that greenhouses are expensive structures, and they must be paid off primarily through an early harvest.

'The greenhouse is covered with film 10—15 days before planting the transplants and, if possible, heated in advance to establish the necessary air and soil temperature.

In March—April, cucumber plants in greenhouses are planted according to the following scheme: 90—100x25—30 or 120x25 cm, i.e., 3.3—4.4 plants per 1 m². The nutrition area is determined by the growing period and cultivar characteristics. The earlier the transplants are planted, the fewer plants are placed per 1 m². The more vigorously the plants branch (F1 Suvenir, F1 Galit, F1 Ksana, F1 Slobozhanskyi, etc.).

Planting transplants and forming the cucumber bush

The planting density of cucumber is determined by the degree of the hybrid's branching. Plants with strong branching (F1 Buyan, F1 Matryoshka, F1 Maryina Roshcha, F1 Chistye Prudy) are planted less densely. For hybrids with moderate or limited branching (F1 Muravey, F1 Kuznechik, F1 Kozyrnaya Karta), the planting density per 1 m² is increased.

When planting, it is important not to bury the stem: cover only the transplant pot with soil. This protects the root collar from rotting and reduces the risk of root rot infection. Overgrown transplants are planted differently — they are buried up to the hypocotyl and kept at an air humidity of about 100% in the greenhouse using misting irrigation to create a fog effect.

2–3 days after planting, the plants are tied to a trellis at a height of 1.8–2 m. To ensure the bushes are better illuminated, they are tied alternately: one to the left trellis, the other to the right. Such distribution allows for the most efficient use of sunlight.

For proper redistribution of nutrients and good light penetration, bushes must be formed. Removing shoots and flowers at the beginning of the growing season helps the plant develop the main stem and robust leaves faster.

1. In the lower 4 nodes of the main stem, completely remove all female flowers and side shoots at the nascent stage.
2. In the next 1–2 nodes, leave the fruit sets but completely remove the side shoots.
3. In the nodes above, pinch the side shoots: in the lower tier — to 1–2 leaves, in the middle — to 2 leaves, in the upper — to 2–3 leaves.
4. Wrap the top of the main stem around the trellis wire. In low greenhouses, pinch it above the 3rd–5th leaf.

In high greenhouses, the top is lowered down and pinched at a distance of 100 cm from the ground (for bee-pollinated cultivars). For parthenocarpic cultivars and to extend fruiting, the stem is pinched 3–5 leaves above the trellis, one side shoot is lowered and pinched every 50 cm, leaving a continuation shoot 100 cm high from the ground. All shoots on the horizontal section of the trellis are completely removed.

Temperature regime, pollination, and soil care

Cucumber productivity directly depends on bee activity and root zone temperature. Insufficient pollination of bee-pollinated cultivars reduces the harvest and stimulates the growth of side branches. This requires additional labor for pruning.

• Hive installation time — 5–7 days before flowering
• Bee density rate — 1 hive per 1000 m²
• Optimal soil temperature — 25 °C
• Minimum soil temperature — 17 °C

In the spring period (March – April), daytime air temperature is maintained at 25–28 °C in clear weather and 21–23 °C in overcast weather. The night regime determines leaf development and shoot branching. For hybrids with fruiting on the main stem, the night temperature is maintained at 16–18 °C before harvesting begins, and at 19–20 °C during the fruiting period.

To reduce the break in fruiting between harvest waves from the main stem and lateral shoots, it is necessary to stimulate root system regeneration. For this purpose, the night temperature is temporarily lowered to 15–16 °C. This technique is combined with top dressing and loosening the soil by piercing it with a pitchfork.

Increasing soil temperature provides a greater boost to the early harvest than heating the air. This is confirmed by the results of practical trials:

To prevent disease and protect against pests, avoid drafts and sudden temperature fluctuations. Open ventilation vents early in the morning, preferring top ventilation. This will help avoid overheating and excessive moisture accumulation.

To obtain a high cucumber harvest in plastic greenhouses, it is necessary to maintain air humidity at a level of at least 85–95 %. In arid regions, this is achieved by combining forced ventilation with fine misting or refreshing irrigation. Such an approach also helps to lower the temperature in the greenhouse and protects the crop from overheating, which is the main cause of productivity drops in southern regions.

• Optimal air humidity — at least 85–95 %
• Humidity during disease spread — 70 %
• Water temperature for irrigation — 20–25 °С
• Refreshing irrigation rate — 1.5–2 l/m²

Refreshing irrigation is carried out between main irrigations by spraying the paths and the soil surface. Immediately after this, the greenhouse is closed for 1–2 hours for rapid air saturation with moisture. When relative air humidity drops, plants respond by slowing down the growth of stems and leaves, and the development of spider mites accelerates on the plantings.

Irrigation of the cucumber — a crop extremely demanding regarding water regime and soil aeration — is differentiated depending on lighting conditions. Only warm water with a temperature of 20–25 °С is used for irrigation. Optimal water consumption rates by month are presented in the table.

Top dressing regimes: root and foliar nutrition

When choosing a root top dressing scheme, the plant development stage and the current soil nutrient supply are taken into account. Practice shows the high effectiveness of organic fertilizers: cow manure solution diluted from 1:4 to 1:8 or poultry manure in a ratio from 1:10 to 1:12. Organic top dressing can be alternated with the application of mineral fertilizers.

If the root system is unable to absorb nutrition properly — for example, during a sudden transition from cloudy to clear weather, due to hypothermia, high soil density, or soil salinization — plants weaken rapidly. In such cases, foliar treatments help the agronomist. They are carried out early in the morning or in overcast weather using a complex nutrient solution.

To increase the cucumber's stress tolerance and reduce the concentration of nitrates in the fruits, it is useful to add physiologically active humic substances and trace elements to the working solution. The following mixture is added to 10 liters of water:

• boric acid — 3 g;
• magnesium sulfate, zinc sulfate, copper sulfate, cobalt sulfate, ammonium molybdate — 0.5 g of each;
• iron citrate — 2 g;
• potassium iodide — 0.1 g;
• sodium humate — 3 g.

As an alternative composition for foliar treatments, a 10% skimmed milk solution can be used. Good results are also obtained by using liquid complex fertilizers with trace elements. For example, in trials where there was a sharp drop in yield and fruit set shedding, a complex of measures helped correct the situation: improved ventilation, timely plant thinning, loosening the soil, and optimizing care.