Cucumbers (Cucumis sativus) are among the most frequently cultivated vegetables. They belong to the pumpkin family (Cucurbitaceae) and their fruits are berries from a botanical point of view, as their seeds are embedded directly in the flesh. Cucumbers have been cultivated for over 3000 years and come from India. Since the 19th century they have also been cultivated in greenhouses in the United States, where a general distinction is made between free-range cucumbers and salad cucumbers. While salad cucumbers, also known as snake cucumbers, are usually cultivated in greenhouses, pickling and peeling cucumbers are suitable for outdoor use, although there are also cucumber varieties for both uses. Cucumbers are annual plants that lie on the ground first, then climb up and, depending on the variety, can form one to four metre long shoots. While field cucumbers and pickled gherkins are cultivated lying on the ground in the bed, salad cucumbers need a climbing frame.
Normally cucumbers are monoecious, female and male flowers grow on a plant. Modern, yield-safe varieties of cucumbers, on the other hand, only produce female flowers that bear fruit even without pollination. In these parthenocarpic (“virgin”) varieties, a fruit develops from each flower. By the way: Many varieties of cucumbers are also sold as grafted young plants. Seedlings of the fig leaf pumpkin (Cucurbita ficifolia) serve as a grafting base. Refined snake cucumbers are more resistant to soil-borne fungal diseases and produce higher yields because they are more vigorous.
Location and soil
Outdoor cucumbers need a warm, humid and wind-protected full sun location in the bed. The soil should be humus and loose, warm up quickly in spring and not prone to silting up.
Cucumbers for snakes and salads also need a warm and bright location. Due to their longer vegetation period and their high heat requirement, they are cultivated almost exclusively in greenhouses in the United States. When using cucumbers in greenhouses, make sure that they are not overshadowed by other plants. In southern regions, greenhouses made of blank glass should be shaded from the blazing midday sun, as the soft leaves burn very quickly, especially when the water supply is poor.
Sowing and planting
Cucumbers can be easily preferred on the windowsill. In this video we show you how to sow cucumbers correctly. Credit: our store/Alexander Buggisch
Cucumbers can be sown directly or pre-cultivated. Direct sowing in the cucumber bed is recommended for robust pickled cucumbers and small-fruited outdoor varieties and is possible from late April/early May to early July. If you are sowing directly into the bed, you should always place three seeds in a planting hole. The distance to the next planting hole should be at least 30 centimetres. You can pre-cultivate snake cucumbers in pots in the heated greenhouse as early as mid-March. The young plant cultivation of outdoor cucumbers in pots can take place both in the greenhouse and on the windowsill. However, this should only be done two to three weeks before planting out, otherwise the young plants will become too large before they reach the vegetable bed. To grow, place two to three seeds each in a pot at least eight centimetres in diameter, half of which is filled with growing soil. When preferred, a high germination temperature of at least 20 degrees Celsius leads to rapid germination success. After germination, cool the plants slightly. Only from the middle of May do you place the young plants in the open-air bed.
You can plant cucumber seedlings in the basic bed of your heated greenhouse as early as the beginning of April. For greenhouses without heating, it is better to wait until the end of April. The seedlings are planted deep and piled up slightly to form additional lateral roots. However, in the case of refined cucumbers, the place of processing must be above ground. Ideally, pickled cucumber seedlings should have only two, pickled cucumbers two to three well-developed leaves. Large preserving jars or glass bells, which are put over the young plants in the field, provide the necessary warmth during the growth phase. When planting out, take care not to damage the roots. The planting distance in the greenhouse is 130 to 170 centimetres between the rows and about 40 centimetres in the row. For outdoor cucumbers, a distance of 100 x 40 centimetres is ideal.
Practice video: How to plant cucumbers correctly
You want to plant cucumbers this year? In our practice video, we show you what you need to pay attention to.Credits: Production/Editing: Fabian Surber, Martin Sterz
Crop rotation and mixed cultivation
Cucumbers should only be grown on the same land again after four years. Good previous crops are cereals, legumes and celery. In addition, fast crops such as lettuce, rocket and radish can grow on the cucumber bed between the rows in order to make optimum use of the cultivation area. After their harvest, the warmth-loving vegetables usually occupy the space on their own.
Cucumbers are strong eaters and also have a high water requirement. It is particularly important to water the vegetables regularly during fruit formation and when they are dry. It is best to pour lukewarm water in the morning. In this way you also counteract the formation of bitter fruits. A mulch layer of straw keeps the soil loose and the fruit clean for outdoor cucumbers. The basic fertiliser used in bed preparation is rotten cow manure (of which about five litres per square metre) and mature compost. In addition, you can occasionally fertilize with horn meal or organic liquid fertilizer such as comfrey liquid manure during the main harvest period. A thin mulch layer of lawn cuttings promotes the growth of cucumbers in greenhouses.
In general, all cucumbers can be raised. Above all, however, snake cucumbers in greenhouses are usually guided by strings hanging from a tightly stretched wire. The new shoots are wrapped around the line twice a week with increasing length. So that the young seedlings are not weakened by too early fruit growth, it is usual to cut all side shoots up to a height of about 80 centimetres after the first leaf base. In the course of cultivation, the main shoot of the plant should also be cut so that it does not become too long. In outdoor cucumbers, the main shoot is usually cut off after the fifth or sixth leaf in order to stimulate the formation of side shoots. The pruning of outdoor cucumbers can be omitted, as can the occasionally recommended bursting of flower buds. In contrast to snake cucumbers, you can grow outdoor cucumbers on the ground or trellis. A two-metre high wire mesh, a comparable climbing frame or even strong wooden piles are suitable for this purpose. Nettle manure diluted with water in a ratio of 1:10 has proven to be a free natural fertilizer for all cucumbers. Alternatively, the plants can also be supplied with a commercial organic vegetable fertilizer from the beginning of June.
Just eight to nine weeks after sowing, cucumbers begin to produce fruit. The more frequently you pick, the richer the cucumber plants will grow new fruit. Snake cucumbers require up to three harvests per week, while pickles ripen almost daily. The freshly harvested fruits are kept in the vegetable compartment of the refrigerator for a good week. They should be consumed while they’re still firm. The water-rich fruits are not suitable for freezing. Outdoor gherkins are usually preserved by picking or boiling.
Salad cucumbers come in different sizes: ‘Eiffel’ and ‘Dominica’ are snake cucumbers up to 35 centimetres long. Medium-length fruits up to 20 centimetres in size form ‘Paska’ and ‘Printo’. Crunchy snack cucumbers only ten centimetres long are ‘Iznik’ or ‘Picolino’. These greenhouse varieties are parthenocarpic F1 hybrids, mostly free of bitter substances, with high resistance to common diseases. Each flower can produce a fruit in these varieties. Gergana’ is an almost smooth-shelled, slim cucumber for outdoor use. If you prefer the plants, ‘Johanna’, ‘Hoffmans Giganta’ or ‘Chinese Snakes’ cucumbers are also suitable for outdoor cultivation in mild regions and sunny, warm locations. Qualitas’ is a high-yielding and vigorous cucumber, which is suitable for both outdoor and greenhouse use. La Diva’ feels just as at home outdoors as it does in the greenhouse. Its fruits are poor in kernels and completely bitter-free.
Cucumber seeds in the our store shop
A new variety for the greenhouse is ‘Helena’ with long smooth fruits and dark green colour. It forms only sporadic male flowers. Conquerer is an old variety with big fruits. Field cucumbers can be well prepared and boiled down as mustard cucumbers. Marketmore’ is suitable for this with its dark green, smooth fruits and can weigh up to two kilograms when fully grown. Seed resistant pickled gherkins include ‘Vorgebirgstraube’ and ‘Vert Petit de Paris’. Picklebush’ can be harvested as a classic pickled cucumber or at a length of about 15 centimetres as a small land cucumber. There are also round fruit cucumbers such as ‘Limona’ with yellow fruits or ‘White apple cucumber’ with white apple-shaped fruits.
Diseases and pests
Most frequently, downy mildew (Pseudoperonospora cubensis) occurs, especially on cool nights with increased dew formation. One recognizes an infestation by yellow delimited spots on the upper side of the leaf, which gradually turn brown before the leaf dies. As a preventive measure, you should only water the plants in the lower part and administer horsetail manure every two weeks. It can also help to let the plants grow on a trellis so that they can dry off better.
Vegetable fertilizer in the our store-Shop
Powdery mildew occurs mainly in greenhouses after drought: On the surface of the leaves, a spot-like, white fungal lawn forms, which eventually causes the leaves to die. Larger planting distances during planting reduce the risk of infestation. Resistant varieties can also be selected from the outset. For example the cucumber ‘Bella’ or the pickle ‘Excelsior’ are suitable. Spider mites often occur in greenhouses. They can be fought here very well with beneficial insects such as predatory mites, predatory bugs or net-wings. Damage to the root neck of young plants is characteristic of millipedes.
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