CUCUMBERS

pH: 5.5-6.5
Plant spacing: 30-60 cm (depending on variety; 2-5 plants/m2) Germination time and temperature: 3-7 days; 20-30 °C
Growth time: 55-65 days
Temperature: 22-28 °C day, 18-20 °C night; highly susceptible to frost. Light exposure: full sun
Plant height and width: 20-200 cm; 20-80 cm
Recommended aquaponic method: media beds, DWC

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Growing cucumbers in aquaponic units: Cucumbers, along with other members of the Cucurbitaceae family including squash, zucchini and melons, are excellent high- value summer vegetables. They are ideal plants to grow in media bed units as they have a large root structure. Cucumbers can also be grown on floating rafts, although in grow pipes there could be the risk of clogging owing to excessive root growth. Cucumbers require large quantities of nitrogen and potassium, thus the choice for the number of plants should take into account the nutrients available in the water and the fish stocking biomass.

Growing conditions: Cucumbers grow best with long hot humid days with ample sunshine and warm nights. Optimal growth temperatures are 24-27 °C during the day with 70-90 percent of relative humidity. A temperature of the substrate of about 21 °C is also optimal for production. Plants stop their growth and production at 10-13 °C. It is recommended to have higher potassium concentration to favour higher fruit settings and yields.
Growing instructions: Cucumbers seedlings can be transplanted at 2-3 weeks at the 4-5 leaf stage. Plants grow very quickly and it is a good practice to limit their vegetative vigour and divert nutrients to fruits by cutting their apical tips when the stem is two metres long; removing the lateral branches also favours ventilation. Further plant elongation can be successively secured by leaving only the two farthest buds coming out from the main stem. Plants are encouraged to further production by regular harvesting of fruits of marketable size (> 180 g for slicing varieties). The presence of pollinating insects is necessary for good fecundation and fruit set. Cucumber plants need support for their growth, which will also provide plants with adequate aeration to prevent foliar diseases (powdery mildew, grey mould). Owing to the high incidence of pest occurrences in cucumber plants, it is important to plan appropriate integrated pest management strategies (see Chapter 6) and to intercrop the plant unit with plants that are less affected by the possible treatments used.
Harvesting: Once transplanted, cucumbers can start production after 2-3 weeks. In optimal conditions, plants can be harvested 10-15 times. Harvest every few days. to prevent the fruits from becoming overly large and to favour the growth of the following ones.