Agricultural practices for growing cucumbers in greenhouse and open soil

Specifics of cucumber care in greenhouse conditions

Fertilize plants with a potassium nitrate solution (three tablespoons per 10 L of water per 2 m2). Plants should be irrigated moderately, but more frequently after flowering, while avoiding excessive soil moisture.

Before each irrigation, until the vines have spread, plants should be hilled up to avoid flooding the stem. Soil may be loosened only until the vines form, after which loosening is replaced by top-dressing with soil (preferably a nutrient mixture).

Ventilation should be carried out carefully so as not to chill the tender plants, but overheating, which can occur at temperatures around 35°C, must also be prevented. The temperature can be lowered by folding the film on the leeward side, but inward rather than outward, so that the batten with the film does not slip.

Simultaneously with cucumbers, leafy vegetables can be grown under the film by sowing pre-germinated seed:

• leaf lettuce;
• peking leaf cabbage;
• green onions;
• dill for greens.

Organization of heating and soil mulching

Under film covers, the soil can be heated by placing hot manure in grooves 30—35 cm deep and wide in a 20 cm layer, and topping it with a nutrient mixture. The experience of amateur G. G. Emelyanov from Leningrad is noteworthy. In the autumn, instead of manure, he places tree leaves and sawdust into trenches 50 cm deep and wide; in the spring, he adds leaves slightly above the soil level, compacts them, and fills them with food waste accumulated and dried during the winter, sprinkles them with lime, then with superphosphate, pours hot water over them, then adds a 20 cm layer of soil mixed with ash, followed by a layer of peat on top, after which he covers the 1 m wide bed with a film on a frame and sows cucumber seed five days later. After the harvest, he removes the soil from the bed and fills the trench again with leaves and food waste.

Using film for mulching the soil yields the same results as using humus or peat, but it eliminates the need for soil loosening after irrigation or rain, preserves its structure, reduces the need for irrigation, and under black film, weed seedlings die.

The disadvantage of transparent film is that it transmits thermal rays, resulting in lower soil temperature at night; at the same time, fine moisture droplets settle on the film, which reduces heat loss from the soil. Furthermore, the humidity of the air layer near the ground above it is lower than in an open area, so on hot days it is necessary to humidify the air by spraying cucumber plants using a hose or watering can. In this case, water heating is not needed.

Methods for growing cucumbers under film

A method of growing cucumbers proposed by Professor O. V. Yurina (All-Union Institute of Vegetable Crops Breeding and Seed Production) is noteworthy. She proposed sowing cucumber seed in mid-May in deepened holes in 70x70 cm clusters, then completely covering the plots under the cucumbers with film. With the onset of warm weather, the film above the seedlings should be cut crosswise, and the plants continue to grow and develop above the film. Four plants should be left in each cluster.

Technology of soil preparation for cucumbers

In open ground, manure can also be placed under beds, just like under film covers, but it is better to do it using the method of Novgorod gardeners. They perform the work in the following sequence:

• Place hot manure at the end of April between last year's beds in a layer 40 cm thick and 50 cm wide.
• Divide the old bed into two parts, creating a furrow down its center.
• Cover the manure from above with only a 5 cm layer of fertile soil taken from the furrow.
• Only pile the soil against the manure from both sides.

In favorable years, on sites protected from the wind, harvesting begins from the second ten-day period of June, and in unfavorable years, from the beginning of July.

Agrotechnology of growing cucumbers in open ground

For growing early cucumbers, the plot should have a slight southern or southwestern slope and be protected from cold northern and eastern winds. Cucumber plants located on a southern slope make better use of solar energy.

The drainage of cold air from the slope reduces the danger of frost, and protecting the site from cold winds preserves the heat gained by the soil and plants, contributes to increasing the relative humidity of the air among the plants and increasing the carbon dioxide in the protected space at the leaf surface level. And what if there is no plot with such a slope? In this case, one needs to cut high ridges on the site, make a gentle slope on the southern side, and make holes in the middle of it, into which the prepared seed should be sown.

Cucumbers are usually sown one week before the last frost. As a safeguard, one should sow dry, soaked, and sprouted seeds simultaneously. There may be no frost, but seedlings from sprouted seeds produce the earliest fruits. If seedlings from sprouted seeds die from frost, those from soaked seeds will emerge; if those die, dry seeds will emerge, albeit later. To accelerate the growth and development of plants, they should be covered at night if the nights are cold, fed with a weak fertilizer solution, and provided with increased carbon nutrition by mulching them with fresh manure. The rapid appearance of lateral shoots, and female flowers on them, is promoted by pinching the plants above the fourth or fifth leaf, taking care not to damage the apical bud. Pinching halts the plant's vertical growth, thereby accelerating the appearance of lateral shoots. After flowering, the growth of the main shoot resumes. All cultivars should be pinched, except for hybrids and the 'Altaysky Ranny' cultivar. Seeds can be sown in single rows at a distance of 60 cm for the 'Altaysky Ranny' cultivar and 70 cm for other cultivars, but it is better to arrange plants in double-row strips with 80—90 cm between the strips and 40—50 cm between the rows. Seedlings of the 'Altaysky Ranny' cultivar are thinned out: first when the first true leaf appears — to 5 cm, and finally when the third leaf appears — to 10 cm, while other cultivars are thinned to twice that distance. When thinning seedlings, do not pull the plants out, so as not to damage the roots of the remaining plants; instead, pinch them off. After thinning, the plants are slightly hilled so that water does not stagnate near the stems, otherwise damping-off is possible. Loosening the soil after every irrigation or rain until the canopy closes is also mandatory. To obtain early and uniform emergence, mulching — covering the sowings with humus or peat in a layer of 2 cm — is a necessary technique that promotes moisture retention and ensures better seed germination. The seeding depth in this case can be reduced to 2—3 cm (instead of 3—4 cm). In case of a shortage of peat or humus, one can limit mulching to a narrow strip 5 cm wide. Mulching the soil immediately after sowing seeds has a beneficial effect on the water, thermal, and nutrient regimes of the soil. Mulch prevents the formation of a soil crust and reduces moisture evaporation from the surface, preserving its supply in the soil. Under mulch, the soil releases heat slowly; at the same time, the surface air layer becomes warmer thanks to the dark color of the mulch and the resulting better absorption of solar rays. Improved water and thermal regimes contribute to the increased development of soil microorganisms and the accumulation of nutrients in the soil. Along with this, the carbon dioxide content in the surface air layer increases, and photosynthesis is enhanced.

To warm the soil in trenches of the width of the bed and 30 cm deep, one can place not only manure but also rotting waste, grass clippings, or chopped straw in a layer of 10—12 cm, sprinkling them with superphosphate (one cup per 1 m2). On top, one pours fertile soil mixed with ash (one cup per bucket of soil), or with a garden mixture (three tablespoons), or with nitrophoska (two tablespoons per bucket). Not only beds but also ridges can be warmed with manure. Ridges should be made so that the base of the ridge is 90 cm wide, 20—25 cm high, with a wide southern slope at an angle of 30—35° and a steep northern one. Manure should be placed in the center of the ridge at the same time. Sprouted seeds or transplants are placed on the ridge in a staggered pattern in two rows. Applying compost enriched with superphosphate at a rate of a half-liter jar per 1 m into the rows or planting holes promotes early fruiting and higher cucumber yield. Peat-fecal compost, also enriched with superphosphate, is more effective, but this compost can be used only after the unpleasant odor has disappeared. An early cucumber harvest is also obtained when grown under the protection of windbreaks made of tall-stemmed plants (corn, fava beans). Beans, as cold-hardy plants, are sown as early as possible in two rows with 15 cm between the rows, and corn — simultaneously with cucumbers, also in two rows after every four rows of cucumbers. By the time of cucumber emergence, the beans protect the young plants, and the corn, as it grows, protects the adult plants. Windbreaks should be positioned perpendicular to the prevailing winds. Windbreaks protect cucumbers from cold winds. Inside the windbreaks, the temperature rises, and increased air humidity and higher carbon dioxide content are maintained among the cucumber plants. As a result, not only does fruit harvesting start earlier, but the duration of fruiting also increases. In addition, windbreaks protect the plants from having their vines turned over by the wind (when turned over, additional roots are torn from the stems, which impairs plant nutrition). As protective windbreaks, one can use carrots or beets by sowing sprouted seeds in early spring at a distance of 10 cm from the intended cucumber row on the north side.

To accelerate fruiting, it is necessary to provide cucumber plants with nutrients from the moment of seed germination, especially phosphorus. Later, to strengthen the development of the leaf apparatus, the plants are fed with a urea solution (two tablespoons per bucket of warm water), and during the fruiting period — with potassium nitrate (three tablespoons per bucket of water). Such top dressing is especially effective during the decline of fruiting, when weakened leaf growth cannot ensure normal fruit development. To obtain an early and high yield of cucumbers, along with fertilizer application, the crops must be regularly irrigated. Without irrigation, plants use fertilizers to a lesser extent, especially during dry periods. In addition to regular irrigation with subsequent shallow loosening of the soil, refreshing irrigation with a sprayed stream through a hose is necessary on hot days. In this case, one need not fear cold water. Refreshing irrigation with small application rates not only increases the air humidity among the plants but is also a means of combating plant overheating. Refreshing irrigation is indispensable during hot, dry winds, which also occur in the Moscow region, when air humidity drops sharply and the water balance in plants is disrupted to such an extent that they not only wilt but sometimes dry out. To avoid manual pollination, one should attract bees; for this, at the beginning of flowering, cucumbers should be sprayed with a honey solution (two tablespoons per 1 L of water) in the first half of a sunny day. Early spring sowing of coriander also helps attract bees. Cucumber yield is significantly influenced by the regularity of fruit harvesting: every day or two at the beginning of fruiting and daily during mass fruiting. If a harvest is skipped, the fruits become overmature, nutrients go toward seed development, and the growth of young fruit sets and the formation of new ones are delayed. Moreover, careless harvesting (leaving deformed, diseased, and overmature fruits on the vines) leads to the same result. Fruits should be picked very carefully; do not tear them off, but pinch them by pressing your thumbnail onto the peduncle. To avoid breaking the roots that have formed where the shoot touches the ground, the vines must not be lifted during harvesting. It is best to harvest fruits in the morning: cucumbers picked at this time retain their freshness longer. Sometimes bitter fruits are encountered. This occurs due to the accumulation of cucurbitacin in them, caused by unfavorable conditions that delay fruit growth (very cold or very hot weather, lack or excess of moisture, irrigation with cold water, as well as a lack of nutrients during the period of mass fruiting).

Plant protection from pests and diseases: After harvesting, all plant residues must be removed, burned, and the ash used as fertilizer. Do not allow weeds to proliferate not only in the plot but also around it, as they are a breeding ground for pests and diseases; for example, the spider mite develops on orache, nettles, and bindweed. If cucumbers are grown in a greenhouse, it is disinfected with chlorinated lime (400 g of lime is infused in a bucket of water for 3—4 hours, then the liquid is carefully drained for spraying, and the residue is used to coat wooden parts). The soil is disinfected with a carbathion solution (100 g per bucket of water per 1 m2), tilling it before and after applying the solution, then covering it with film, and loosening it again after 10 days. It is better to do this in the autumn, as in the spring this work must be carried out no later than 20 days before planting transplants, which would mean missing the early planting date. A dangerous cucumber pest is the spider mite. As a result of its bites, light yellow spots appear on the leaves; they turn yellow and dry up. When the pest appears, the plants are sprayed with a suspension of seedlings and fruiting. The minimum temperature for fruit growth is 15°, the optimum is 26—27°C. Readiness for harvest for summer squash (zucchini) occurs in 50—60 days, for pattypan squash — 5—7 days later, depending on weather conditions. However, early harvests of summer squash and pattypan squash are obtained by planting 20—25-day-old transplants grown in pots with a nutrient mixture, 10 cm in diameter. Sowing seeds and planting pattypan squash transplants are carried out at the same time as cucumbers, in pre-prepared deep holes 30 cm in diameter, and half a bucket of humus or compost mixed with superphosphate (a matchbox size) is added to each hole. The distance between plants is 70 cm. With good soil fertilization, one can limit oneself to adding a liter jar of humus or compost to the hole when planting transplants. Summer squash and pattypan squash should be watered at the roots, combining irrigation with top dressing with a garden mixture (three tablespoons per bucket of water) or nitrophoska (two tablespoons), initially 1 L per plant, then 2 L. Plants are watered less frequently but with larger rates than cucumbers, as they have a more powerful root system. Pinching the upper main stem during budding promotes higher fruit yield. Fruits are harvested every six to eight days, and it is better not to tear them off, but to cut them with a knife along with the peduncle. After each harvest, the plants are watered with a garden mixture solution, increasing the rate to 3 L per plant. For an early harvest, summer squash and pattypan squash are grown under film covers, planting three-week-old transplants. They are grown on the same nutrient mixture as cucumber transplants. Under film covers, transplants are planted in two rows with row spacing of 50 cm, and 70 cm between plants in a staggered pattern. Three to four weeks before planting under the film, one can sow sprouted Beijing cabbage seeds in three rows, and plant summer squash and pattypan squash transplants in the middle row every 70 cm. Summer squash and pattypan squash plants suffer from overheating more than cucumber plants, so film covers and greenhouses need to be ventilated more often. The film can be removed when stable warm weather arrives, but without allowing the plants to touch the film as they grow. Early cultivars: summer squash — 'Gribovsky 37', pattypan squash — 'Belye 13'.

EARLY TOMATOES: Tomatoes have a long growing season. Under favorable conditions of temperature and soil moisture, seedlings appear about a week after sowing seeds. From emergence to the appearance of buds in early-ripening cultivars, about eight weeks pass, and the same amount from the start of flowering to the ripening of the first fruits. The duration of natural fruiting of tomatoes in the open ground is limited by the frost-free period. Near Leningrad, for example, the fruiting period does not exceed 20 days; near Moscow, in favorable years, it lasts up to 60 days. After the formation of seven or eight leaves in early-ripening cultivars, the first flower cluster is set, then dormant buds in the leaf axils below the flower cluster start to grow. They produce lateral shoots, or suckers, and the bud from the axil of the lower leaf starts growing first, but the upper sucker shoot growing directly under the flower cluster has faster growth. It is this one that should be left during pruning to obtain the earliest harvest. In early-ripening cultivars, each subsequent cluster on the main shoot is set after one or two leaves. The first cluster is also set on the upper lateral sucker shoot. At this time, the second flower cluster is formed on the main shoot. On the lower lateral shoot, although it starts growing earlier than the upper one, the first flower cluster is formed just as it is on the main shoot, after the appearance of the seventh or eighth leaf. Determinate cultivars branch significantly less than indeterminate ones. Under favorable conditions, the growth of plants, with the exception of determinate cultivars, is continuous. For example, in greenhouses, plants reach several meters in length, and such cultivars as 'De Barao' or 'Gigant' grow up to 4 m in the open ground. Simultaneously with growth, flower clusters are also formed. However, the formation of new flower clusters and new fruit sets delays fruiting on the first flower clusters, and consequently, early fruits cannot be expected in this case. That is why, to obtain an early harvest, one must systematically remove lateral sucker shoots and limit the number of flower clusters. Amateur vegetable growers are concerned about the frequent dropping of flowers and fruit sets that produce the very first fruits. How can the plant be saved from this undesirable phenomenon? After all, losing the first flowers means losing the earliest harvest. In greenhouses, flowers fall off as a result of low temperature and high air humidity, when anthers do not crack and moist pollen does not fall out of them. After all, tomato plants are self-pollinating, and cross-pollination is observed only in the south. In addition, flower dropping is observed at high night temperatures, when there is insufficient outflow of nutrients from the leaves due to their increased consumption for respiration. Insufficient lighting is also a cause of flower dropping. As already mentioned, tomato plants are distinguished by an increased demand for phosphorus nutrition starting from seed germination, which means a lack of phosphorus can also be a cause of flower dropping when growing plants in both protected and open ground. Air humidity must not exceed 65—70%. In open ground, one more reason for flower dropping should be added to this — planting overgrown transplants; they should be no more than 25 cm in length with a stem diameter of at least 1 cm. Flower dropping can also occur when planting transplants in cold soil and when watering with cold water or when watering by overhead irrigation. Excessive soil moisture must also be avoided. A lack of moisture at high air temperatures is also a cause of flower and fruit set dropping. Some gardeners also apply a large amount of organic fertilizers to tomatoes. This is permissible, but only if the excess nitrogen is balanced by the application of phosphate fertilizers. An excess of nitrogen with a lack of phosphorus and potassium leads to the dropping of flowers and fruit sets. On sandy soils, this phenomenon is caused by a lack of magnesium. Applying potassium-magnesium fertilizer (1—1.5 kg per 100 m2) prevents the dropping of flowers and fruit sets. The cause of flower and fruit set dropping is also a lack of trace elements. This deficiency can be eliminated by foliar feeding the plants with micro-fertilizers.

For tomato fruit setting, 1180 mg (1 g of Riga fertilizer per 10 l of water) or spraying plants with a solution of boric acid (1 g per 1 l of water) is used; however, use a cooled solution for spraying. Two days later, repeat spraying, but with a potassium permanganate solution of the same concentration. A few words about the peculiarities of the tomato root system. The bulk of their active root system is located in the loosened soil layer. 20 days after planting the transplants, the roots penetrate to a depth of 40 cm, reaching 75 cm in diameter, and after another 20 days, both the length and width of the root system reach 100 cm. With natural plant growth, the roots spread up to 2.5 m in diameter, but when removing suckers and, consequently, reducing the assimilation apparatus (leaf surface), the power of the root system is significantly reduced; hence the need to create better conditions for such plants regarding nutrition and water supply. Moreover, plants with a limited number of stems are planted more densely. Tomatoes have the ability to easily form additional roots upon prolonged contact of the stem with moist soil, so a necessary condition for plant care is their hilling. Tomatoes are heat-demanding plants. Their seeds germinate at a temperature of 13—15°C, cold-resistant cultivars — at 10°C, and hardened seeds — even at 8°C, but the optimal temperature for seed germination is within the range of 20—25°C, when seedlings appear five to seven days after sowing. The same temperature is favorable for the adult plant as well. At a temperature below 15°C, flowering is suspended, and below 10°C, growth also stops, with the exception of cold-resistant cultivars, which continue to grow even at 8°C. Such cultivars withstand short-term frosts in windless weather down to —1°C. A prolonged decrease in temperature to 10°C leads to flower drop and a delay in fruiting by 10—12 days. When growing tomatoes under film covers, one must not allow the temperature to rise to 30°C; otherwise, the pollen loses viability and the fruit yield decreases. Growing tomatoes in film greenhouses. As early as the beginning of April, it is necessary to prepare film greenhouses with biological heating for planting 45—50-day-old containerized transplants grown indoors. Naturally, the greenhouse should be installed in a place so that it is not shaded by buildings or trees. After clearing the site of snow, the frame is covered with film, and for faster soil warming, it should be covered with old film. When the ground thaws, a layer of manure 70 cm wide and 30 cm high is laid along the greenhouse onto the dug-up soil, and on top of it, compost or nutrient soil