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Cucumber

Grown up a string rather than along the ground, one plant gives you a cucumber every couple of days all summer.

1. Sow two seeds per 9 cm pot, 2 cm deep, on edge, at 20 to 25 C, and keep the strongest.
2. Do not sow too early. A cucumber that sits in a cold pot for three weeks never catches up.
3. Set up the support before planting: a vertical string or 1.8 m cane per plant.
4. Plant out after all frost risk, on a slight mound, with the rootball just proud of the soil.
5. Mulch with 5 cm of compost and water into a sunken pot beside the plant, not onto the stem.
6. Twist the main stem around the string every few days and tie loosely as it climbs.
7. Pinch out side shoots two leaves beyond a developing fruit to keep the plant manageable.
8. Pick every two or three days from the moment the first fruits are full length.

Soil

Rich, deep, well-drained soil at pH 6 to 7 with a bucket of compost per planting hole.

Sun

Full sun with shelter from wind. Outdoor ridge types take more sun than greenhouse types, which scorch.

Water

Very thirsty: 5 to 10 litres per plant per week outdoors, more under cover, always at the base and ideally with tepid water. The fruit is 96 percent water.

Spacing

45 cm apart when trained up strings, 90 cm apart if left to trail

Depth

2 cm deep, seed on its edge

Care

['Feed weekly with a high potash liquid feed once the first fruits set.', 'Remove male flowers on all-female greenhouse varieties, since pollinated fruit turns bitter and seedy. Outdoor ridge types need their male flowers, so leave them.', 'Never let the plant dry out. A dry check gives bitter fruit and dropped flowers.', 'Keep the greenhouse humid and shaded in high summer to hold off red spider mite.', 'Pick constantly, because one oversized cucumber left on the vine stops the plant setting more.']

Harvesting

Cut with a knife or secateurs, leaving 1 cm of stalk. Pick when the fruit is even in thickness along its length and the skin is firm and glossy, which for most varieties is 15 to 20 cm. Early morning picking gives the crispest fruit.

Storing

Cucumbers do not store. They keep about a week wrapped in the fridge, though below 10 C the flesh turns watery, so the salad drawer is better than the coldest shelf. The real answer to a glut is pickling: small ridge or gherkin types in vinegar brine, or fermented in a 3 percent salt brine with everything kept under the liquid.

Grow it next to

Good with beans, peas, sweetcorn, radish, dill and nasturtium. Keep away from potatoes and from strongly aromatic herbs such as sage.

Problems

[{'cause': 'Stress from dry roots, cold nights or big temperature swings, and in some varieties pollination of all-female types', 'fix': 'Water consistently and mulch. Remove male flowers on all-female greenhouse varieties. Bitter fruit is not dangerous but is not worth eating.', 'symptom': 'Bitter fruit, especially at the stalk end'}, {'cause': 'Powdery mildew', 'fix': 'Water the roots deeply, keep the leaves dry, remove the worst leaves, and improve airflow. Choose resistant varieties next season.', 'symptom': 'White powdery film across the leaves from midsummer'}, {'cause': 'Poor pollination on outdoor types, or the plant carrying too many fruits at once', 'fix': 'Hand pollinate outdoor plants in the morning, and thin to two or three developing fruits per stem section.', 'symptom': 'Small fruits shrivel and drop at the tip'}, {'cause': 'Red spider mite in hot dry still air', 'fix': 'Damp down the greenhouse floor daily, ventilate, spray the leaf undersides with water, and remove badly affected leaves.', 'symptom': 'Fine webbing and dry stippled leaves under cover'}, {'cause': 'Stem or root rot from water sitting around the crown, or cold wet soil', 'fix': 'Plant on a mound, water away from the stem, and never plant out until the soil is genuinely warm.', 'symptom': 'Whole plant wilts and collapses even though the soil is wet'}]

Saving your own seed

Cucumbers cross readily with other cucumbers, though not with melons or squash. Leave a fruit on the plant until it goes fat and yellow-brown, which is well past eating stage, then scoop the seed, ferment it in water for two days, rinse and dry. Do not save seed from all-female F1 greenhouse varieties.

Containers

Good in a 30 litre pot with a 1.8 m cane or string to climb. Choose a compact or mini variety, water daily in summer, and feed weekly, because a pot cannot buffer a thirsty plant.