Greenhouse varieties of small cucumbers are popular. Self-pollinating, high-yielding varieties of small cucumbers, such as Mandy F1, Mirabelle F1, Amour F1, Pasalimo F1, Profi F1 and Octopus F1, are popular and grown in heated and unheated glass and polytunnel greenhouses.
Sowing. For cucumbers grown in heated greenhouses, seeds should be sown between January and 15 March, and for those grown in unheated greenhouses, seeds should be sown later, by 15 April. Cucumber seeds are sown directly into peat or plastic pots 10-12 cm in diameter (without transplanting), filled with peat substrate for sowing (pH 5.5-6.5; EC-1.2-1.8 mS/cm). The seed is placed horizontally at a depth of 1-2 cm. Cucumber seeds of foreign selection are ready for sowing and do not need to be additionally treated. Although cucumber seed lasts a long time, it is recommended to sow seeds that are 2-3 years old, because sowing older seed will result in lower yields.
During germination, the pots containing the sown seeds are covered with polythene film and an agro textile. The seeds are germinated at a temperature of 24-28 °C and sprout within 2-3 days. Seeds sown in rotten, cold, wet soil will rot. After sprouting, the temperature is then reduced to 23 °C (day and night) for 10 days to prevent the sprouts from wilting.
Growing seedlings. Cucumber seedlings are grown in heated greenhouses, preferably on racks heated from below. The potted plants are placed on the racks at a density of 15 plants/m2 to prevent contact with the leaves, so that the cucumber seedlings will grow sturdy, compact and not droop. During the growing period, the temperature is maintained at 22 °C during the day and up to 18-20 °C at night. If the temperature is high at night, the seedlings will dry out. The temperature of the substrate is very important for the growth of cucumber seedlings and must be between 18 and 20 °C. Cucumber roots cannot absorb nutrients at temperatures below 10 °C.
The cucumber seedlings should be watered infrequently but abundantly with warm water, at a temperature of 22-25 °C, in the first half of the day. The peat substrate should be moist but not wet. To ensure that the cucumber seedlings grow with a well-developed root system and are vigorous and of good quality, a solution of Ruter AA and Humistar is applied (1 litre of each of these fertilisers is dissolved in 1 m3 of water).
Cucumber seedlings are given a prophylactic watering against root diseases with a 0.15% concentration of Previcur before being planted in their permanent site. Cucumber seedlings grow up in 25-30 days. Seedlings suitable for planting must be 25-30 cm tall, have 5-6 leaves and a well-developed, white root system.