Cucumber growing techniques

Crisp and juicy, cucumbers are an essential ingredient of cool summer salads; and the gherkin varieties are ideal for pickling.

There are two main types of cucumber: outdoor and frame (or greenhouse) varieties. Outdoor, or ridge, cucumbers were originally grown on ridges of loam or well-rotted garden com-post. They are hardier than frame types, being less dependent on high temperatures and humidity. They thrive in rich, moist soil in the open ground, or in peat bags or tubs.

Older varieties of ridge cucum-ber – short and squat, with knob-bly skin – were once regarded as inferior to frame types. However, many new varieties of outdoor cucumber are long, smooth-skinned and delicious.

Besides standard ridge varieties, there are Japanese, apple and gherkin varieties. Japanese varieties have exceptionally long, smooth fruit, improved disease resistance and tolerance to cold. Apple cucumbers, and the similar lemon cucumber, are small, round, pale-coloured, juicy and crisp; gherkin varieties produce small warty fruits, suitable for pickling.

Ridge cucumbers require polli-nating so, unlike frame cucum-bers, male flowers are retained. Frame cucumbers may reach 45cm (18in) or more in length and well-grown specimens are straight, cylindrical and smooth-skinned.

GROWING OUTDOOR CUCUMBERS

All danger of frost has passed.

Alternatively, sow directly into the planting pockets – in late spring in mild areas or later in cooler regions (up to the end of late spring or early summer). Sow three or four seeds 2.5cm (lin) deep and 7.5cm (3in) apart in the centre of each pocket. Protect with cloches until early summer – or later if the nights continue cold and remove all but the strongest seedling from each group.

Looking after the crop

Naturally bush types need no training and you can grow them on the flat. Other types can be grown on the flat but pinch out the growing tips when there are six leaves. Alternatively, you can grow them up a fence or tripod – pests and diseases, outdoor cu-cumbers must not be planted in the same spot year after year.

Site and soil preparation

Outdoor cucumbers like a sunny, sheltered position and well-drained soil, high in organic matter to retain moisture. Grow them on level ground, in pockets of fertile soil.

Prepare the pockets in late spring, a week or two before planting time. First dig a square hole 30 x 30cm (1 x 1ft) for each plant, allowing 60-90cm (2-3ft) between holes. Fill the holes with a mixture of well-rotted garden compost or manure and fine soil, and rake in some general fertilizer.

Grow gherkin varieties in the same way as ridge cucumbers. Alternatively, grow them in 23cm (9in) pots and train the plants upwards on a cane and wire support.

Sowing and planting

In mid spring, sow two or three seeds 12mm (Viin) deep in 7.5cm (3in) pots filled with seed com-post. Cucumber seeds need a temperature of 23°C (75°F) to germinate, so place the pots in an airing cupboard or near the greenhouse heater. Remove the weakest seedlings, leaving one in each pot. Pot the seedlings on if necessary and harden them off in late spring. Plant them out in the prepared sites towards the end of late spring or in early summer, when this method is especially suitable D for the vigorous Japanese types. E Water round the plants to keep n the soil continually moist. Feed f them regularly with a liquid fcrtil-v izer or specially formulated cu-) cumber feed. Protect them with e slug pellets. When the fruits begin h to swell and ripen, keep them off r the soil with pieces of board, straw or polythene.

Harvesting

Cucumbers taste much better if they are harvested before they o reach full size, but they should not n be cut too early. As a rough guide, e the sides of a cucumber ready for picking should be parallel, not dwindling to a point. Always cut cucumbers with a sharp knife -don’t break them off by hand.

Depending on the variety, outdoor cucumbers can be harvested from mid summer to the end of early autumn.

Pests and diseases

Outdoor cucumbers may be attacked by aphids. They are also vulnerable to cucumber mosaic virus, grey mould, powdery mildew and root rots.

Growing frame cucumbers

Frame cucumbers are best grown in a heated or unheated greenhouse, but they can also be grown in a cold frame.

Growing in a greenhouse All varieties need at least 23°C (75°F) to germinate. Standard varieties tolerate reduced temperatures as the seedlings grow, but never let the night temperature drop below 16°C (61°F). All-female varieties need a constant minimum temperature of 2 1°C (70°F). Sowing and planting Sow the seeds in compost-filled 7.5cm (3in) pots between late winter and early spring. Insert one seed edgeways and 12mm (Vim) deep in each pot and place the pots in a propagator, above the greenhouse heater, or in an airing cupboard.

When the seedlings have developed two true leaves, transplant them to the prepared greenhouse bed, again pract18 ing crop rotation, or into growing bags or large pots. The temperature must remain constantly above 16°C (61°F). Fix a vertical stake beside each plant.

Looking after the crop When the plants have grown to about 2.4m (8ft), or up to the greenhouse roof, pinch out the tips of the leading shoots to encourage the growth of lateral shoots. Fix support wires across the greenhouse from one glazing strut to another, about 30cm (12in) from the glass, and train the lateral shoots along them, securing them with twine.

If no cucumbers appear on the laterals by the time they are 60cm (2ft) long, pinch out the growing tips. If laterals do produce fruit, pinch the growing tips out just beyond the second leaf after the first cucumber. Laterals often put out fruit-bearing side shoots. Pinch these out in the same way as the laterals themselves.

Remove male flowers regularly from varieties that bear flowers of both sexes. The female flowers are easy to distinguish – they have a small swelling immediately behind the flower.

Shade the plants from strong sunlight, water them well and keep the air well ventilated and moist by spraying the greenhouse floor twice a day. Once the fruits begin to swell, feed the plants with fertilizer every fortnight.

Growing in a cold frame Prepare the planting stations by the beginning of late spring, and set the plants out a few weeks later. Sowing and planting Sow seeds in pots in late spring, as for green-house cultivation, and leave them to germinate in the cold frame.

Transplant the seedlings when they are growing well, placing one underneath each frame light at the highest point of the frame. Then replace the frame lid and cover the glass with greenhouse shading or a coat of whitewash.

Looking after the crop

On warm days, open the frame 5cm (2in) on the sheltered side, using a wedge, but close it to just a crack at night. Water the plants frequently during hot weather, and spray the inside of the frame twice a day with water to create humidity.

Harvesting

Frame cucumbers have a longer cropping season than outdoor varieties – from the end of early summer to at least early autumn. Like outdoor cucumbers, they should be harvested before they reach their maximum size, and they are best eaten immediately after cutting.

Pests and diseases

Frame cucumbers are susceptible to glasshouse red spider mites and glasshouse whitefly, in addition to the pests and diseases already listed for outdoor cucumbers.

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