Originally from India, they were grown in large quantities in this country in the latter part of the sixteenth century when they were called cowcucumbers. Plants are very tender while the fruits contain over 95 water – the highest content of any vegetable. For successful cultivation both soil and air must be warm and moist.
Sowing the Seed
Both soil and air temperatures need to be about 65 F while it takes about 5 weeks from sowing take place, the beginning and the end of May.
To avoid root disturbance sow in 8cm pots filled with John Innes No. 1. The seed is placed point downwards and covered with 1cm of compost.
Spray the surface with Chestnut compound to prevent damping off and cover the pots with glass or plastic and paper.
Germination needs to be quick so place in propagator set at 70 F. After germination place in good light but not direct sunlight, maintaining a temperature of at least 60 F at night.
When growth permits move on to a 13cm pot into which is put a 1ft cane for support. After 5 weeks from sowing they will be ready for final positions.
Many growers prefer to sow 1cm deep directly into 13cm pots half filled as before. As growth proceeds so the pot is gradually filled with compost.
Preparation of The Soil
Care must be taken to provide good drainage. For greenhouse border planting a 8cm layer of quite fresh strawy manure should be placed under about a foot of soil. A light dressing of Dolimite Lime can be worked into the top couple of inches.
After the bed has settled apply a base dressing in equal parts of Sulphate of Potash, Bone Meal and Superphosphate.
When planting arrange that the upper surface of soil in the 13cm pot is about 2.5cm above the border soil. Plants should be stationed at least 61cm apart. About 6 weeks change to using complete fertiliser, for example, John Innes base.
Instead of border planting grow bags may be used. Putting the plants direct into the grow bag is all right, 2 per bag, but it is better to use 23 or 25cm bottomless pots, filled with contents of other grow bags, placed on the grow bags after having cut out holes in the grow bag the size of the bottomless pot. Water straight into the grow bag and any fertilisers are applied to the upper pot.
Plants should be encouraged to grow quickly while ensuring the plants are kept healthy.
Maintain a humid not stagnant atmosphere, giving ventilation whenever possible and shade the greenhouse. A fine spray over foliage is beneficial as is dampening down walls and floors. Fairly large quantities of water will be required during the summer and it is important for plants in the greenhouse border to have regular top dressings to cover new roots as they appear which in turn encourages more new roots to appear.
The weight of a plant bearing many fruit is considerable. Stout canes at a slight angle to the vertical are required to secure the main stem while horizontal wires or cord are required at about 23cm intervals.
The main stem is stopped when it reaches the top of the house and all young fruit on this stem should be removed. As laterals or side shoots appear they should be secured to horizontal wires. They should be stopped at two leaves beyond the fruit formed at the 1st or 2nd leaf joint. Allow only 1 fruit to develop at each leaf joint sub-laterals may also form, these should be stopped 2 leaves after a fruit has formed.
Care needs to be taken to see that no male flowers are present to ensure that fruits do not become bitter. By carefully training leaf formation, they can be arranged so as not to impede the straight development of the developing fruit.
A frame 183 by 122cm is required for one plant. Plants, from seed sown about 5 weeks before in the greenhouse, are set out in early June into well-prepared fertile soil. If a hotbed was prepared then plants could be set out in May. Set the plant in a mound made from good loam lightly dusted with hydrated lime in the centre of the frame.
Keep the frame closed to create and maintain a humid atmosphere yet giving adequate ventilation when possible. Ideally one must attempt to maintain a minimum temperature of 60 F at night and about 75 F during the day. It may be necessary to cover the frame at night and shade from strong sunshine to obtain the above temperatures.
Try to ensure that any water given is at the same temperature as the frame and avoid water getting on the stem as it comes from the soil to avoid collar rot.
Take out the growing point after 4 leaves. Of the laterals that are produced select the strongest four training one to each corner of the frame. When side shoots from the laterals are about 15cm long pinch them out.
Further cultivation consists of stopping the laterals when they reach each corner, raise fruit clear of soil using glass or tiles, remove male flowers, and give regular weak liquid feeds.
Ridge or Outdoor Cucumbers
The requirements of warmth and moisture apply just as much to outdoor cucumbers as to those grown under glass. Plants out of doors will tolerate neither cold wet conditions nor being blown about by cold winds.
Planting stations should be prepared well in advance by digging out 1ft cubes of soil, 91 or 122cm between each station. Form in a generous amount of well rotted manure or compost. Replace the soil leaving a slight mound. Towards the end of May sow 2 or 3 seeds at each station.
Plants can be raised under glass as for the greenhouse crop. Such plants should not be put outside until about the second week in June.
In either of the above situations it may be necessary to provide protection depending on weather forecasts.
Male flowers must not be removed from outdoor varieties as pollination is required before the fruits will develop. There will be sufficient insect activity to ensure a plentiful supply of fruit.
Ridge cucumbers are often allowed to trail over the ground. However it may be considered better to construct a supporting frame for both growth and fruit so keeping the latter off the soil, which in turn reduces the possibility of rotting. This method also makes it easier to apply a mulch which in turn helps to conserve moisture and assist in raising the soil temperature. Little training is required, except for taking out the point of the leading shoot when it has made 6 to 8 leaves. This will encourage branching – do not stop any of the side shoots.
For plant growth trailing over the soil it is usual to slip a piece of glass or tile under the fruit. When plants carry a goodly number of fruit, dried blood, 28g in 51t, of water, can be given as a weekly routine. Avoid superphosphate as it can have the effect of helping seeds to develop within the fruit.
Care should be taken not to allow water or liquid fertilisers to splash on to the main stem as this may cause the stem to rot. Regular syringing morning and evening of upper and lower leaves is also recommended.
Grafting of Cucumber Plants
The advantage of grafting is a root system resistant to Fusarium and better to cope with low temperature.
Root stock seeds are sown 7 days later than variety seeds. Plants will be ready for grafting when they have one true leaf about 5cm in diameter.
An oblique downward cut is made in the root stock stem about half an inch below the cotyledons and halfway through the stem. A similar upward cut is made in the cucumber stem again just under halfway into the stem.
Both cuts are married together and held in place by a wide piece of sellotape. Remove the top off the root stock leaving 2 leaves. The two root systems are potted on as usual. The root of the cucumber is cut off at soil level about 14 days after grafting.
Subsequent treatment will be similar for under glass culture although the general growth and root system will be far greater.
These can be grown outside as for ridge cucumbers or in 23cm pots as long as suitable support is provided.
Pests and Diseases
Greenhouse Whitefly - is a different species to the cabbage whitefly but nevertheless similar. Try and control a heavy infestation of the whitefly, as both young and old suck sap from plants which then become sticky with honeydew.
Greenhouse Red Spider Mite - will not flourish in moist conditions. When present they suck sap from the lower side of the leaves which result in the upper leafy surface becoming pale and mottled. There may be a silky web at the periphery of the leaves.
Cucumber Mosaic Virus - causes leaves to have yellow and dark green patches. Plants become stunted and fruit distorted. Plants so affected must be pulled up and burned. The virus is transmitted by aphids.
Botiytis or Grey Mould - affects both stems and fruits, can be particularly troublesome in outdoor cultivation in wet seasons and under glass when insufficient care is taken with ventilation. To prevent such attacks avoid over-watering.
Verticillium Wilt - a soil borne fungus, which causes yellowing of the leaves starting at the base of the plant and developing upwards. Plants so affected should be burned. As a preventative water the soil with a chestnut compound.
The withering of young fruit is usually associated with over-watering and poor drainage. Remove the young cucumbers, reduce the amount of water given to the plant, increase ventilation when possible and use a foliar feed to increase the general well being of the plant.
Powdery mildew is surprisingly common towards the end of the season. A white powdery area appears on both leaves and stems. It is encouraged by dryness at the roots and partly discouraged by careful ventilation.
The conditions under which cucumbers grow is almost ideal for the occurrence and development of various pests and diseases. Too much emphasis cannot be placed on good husbandry.
Finally it may be worth trying the new idea of using greenhouse insect glue traps. These consist of yellow panels coated on each side with non-drying glue which attracts and taps flying insects - ideal for control of aphids and whitefly.
Under Glass: Carmen F1, King George, Cucino F1, Tiffany F1, Jessica F1, Mildanna F1.
Outdoor: Bush Crop F1, King of the Ridge, Burpless Tasty Green.
Gherkin: Libert F1, Conda, Eureka F1.