Whether with small, round or very large fruits: Cucumbers (Cucumis sativus) from the cucurbit family (Cucurbitaceae) are a classic in the vegetable garden. However, not all cucumbers are the same. While cucumbers and serpent cucumbers are usually grown in greenhouses, peeled cucumbers (mustard pickle) and pickling cucumbers (pickles) are particularly suitable for outdoor use.
Do not seed or plant cucumbers too early
In principle, cucumbers need a lot of light and heat. Therefore, wait with direct sowing of cucumbers outdoors until the soil has warmed up sufficiently, at least 13 °C / 55 °F. Also, to be on the safe side, do not plant young plants in the vegetable patch until the last frosts. For early sowings, a black mulch film has proven itself, it raises the soil temperature by about 4 °C / 7 °F. Covering with fleece, buckets or canning jars, which you put over the young plants, can also serve as a heat accumulator.
Cucumbers are often grown indoors and then cultivated in a warm, humid greenhouse. Here, too, do not start sowing too early: Only two to three weeks before planting out, sow the seeds in pots. Otherwise, the young plants will grow too large before they reach the bed or greenhouse. Cucumber seeds germinate fastest at 25 to 28 °C / 77 to 82 °F, after germination they should be placed slightly cooler at about 20 °C / 68 °F. Once the cucumbers have formed two true leaves, they are planted out.
Do not ignore the soil
Regardless of whether they are grown outdoors or in a greenhouse, cucumbers are heavy feeders and require loose, humus-rich soil. Since they are shallow-rooted, the soil must not be allowed to silt up under any circumstances. Therefore, pay attention to a good soil structure, especially in heavy soils. Ideal basic fertilizer for cucumbers is straw-like, half-rotted horse manure, which you already work in when preparing the bed; about five liters per square meter /1.5 gal per 11 sq ft. Alternatively, you can use mature compost, which you enrich with chopped straw. A mulch layer of straw or grass cuttings in the root area is also useful: it keeps the soil loose and moist throughout the cultivation period.
Cucumbers should not be grown again on the same area until after four years, otherwise soil fatigue will occur.
Too close distances, no climbing aid
Those who grow cucumbers, not infrequently have to deal with powdery mildew or downy mildew. To avoid these fungal diseases, you should already pay attention to some points when planting. For one thing, adequate plant spacing is important. In the greenhouse, 130 to 170 centimeters (52 to 68 in) between rows and about 50 centimeters (20 in) in the row are advisable. For outdoor cucumbers, assume 100 x 40 centimeters (40 x 16 in). To prevent the plants from resting directly on the ground and to allow them to dry better, you should also offer them climbing aids. Although this is not absolutely necessary for field cucumbers and pickles, but in principle, all cucumbers can be raised. In the greenhouse, cucumbers are best raised on strings attached to braces under the greenhouse roof. In the open ground, wooden trellises and bean trellises can be used.
Watering cucumbers incorrectly
To achieve a constant and good yield, cucumbers must be continuously supplied with water. As a rule of thumb, a plant needs twelve liters (3 gal) of water per kilogram (2 lbs) of harvested cucumber. The water requirement is particularly high when the first fruits are forming. You also need to reach for the watering can regularly during dry periods. Then water daily with temperate, stagnant water, and preferably already in the morning hours. This way you can prevent your cucumbers from tasting bitter. Also, downy mildew doesn’t get a good breeding ground if the plants go into the night dry. As a preventive measure, you should also water the plants only in the lower root area.
Do not forget to fertilize and clean out the cucumbers
In the growth phase, cucumbers not only need plenty of water, fertilizer should also not be missed out. Organic vegetable fertilizers are recommended, as they release their nutrients slowly and sustainably. Organic gardeners also swear by potassium-rich comfrey or nettle liquid manure, which is diluted 1:10 with water. For healthy growth, it is also advisable to moderately clean out excessively dense foliage. It has proven effective to cut off all side shoots up to a height of about 80 centimeters (32 in) after the first leaves appear. The main shoots of the plants should also be shortened so that they do not become too long.
When harvesting, the following applies: The more often you pick, the more abundantly the plants set new fruit.