As long as you give cucumbers the right growing conditions and care for them correctly, they can be fairly easy to grow and can make a great addition to your polytunnel. Growing cucumber in your polytunnel will involve creating a vertical structure affixed to the crop bars up which the vining plants can grow. Cucumbers are a delicious addition to salads grown in your garden. A polytunnel can make growing cucumbers easier as these structures will make it easier to give cucumbers the warmth, humidity, regular watering and other care and attention that they require.
Cucumbers are best sown in pots indoors and transplanted later to their final growing positions in your polytunnel or elsewhere in your garden. Sow seeds indoors between March and May and move to their growing positions in the polytunnel between May and June. The cucumbers will require a temperature of at least 15 degrees to be maintained as they grow, so it is important not to move cucumbers to the polytunnel too early. Prepare your vertical structure before planting out at its base and train the growing vine up the wire, cane or trellis.
It is a good idea to pinch out the tips of each side shoot two leaves beyond a female flower. You will recognise the female flowers as the ones with tiny fruit growing at the base. If you have chosen an all female variety then all the flowers will have tiny fruit – otherwise, the male flowers must be removed or the fruit can taste bitter and unpleasant.
Keep the soil moist at the base of the cucumber plants and mulch well with well-rotted compost, taking care not to pile it close around the stem. This will help to feed the cucumbers and will help reduce evaporation from the soil in which the plants are growing. When watering, take care to water the roots and try to avoid watering the foliage. To help maintain a high humidity, you can water your paths in hot weather. Cucumbers will also benefit from liquid feeds every couple of weeks – comfrey 'tea' will work well for cucumbers as well as for tomatoes and other fruiting crops.
Legumes such as peas and beans can be good companion plants for cucumber and may be grown up the same vertical structure. Nasturtiums, marigolds, sunflowers, and radishes may all be beneficial for pest distraction or as repellents.
Cucumbers should be available for harvest from July through to October. It is best to cut the fruit from the vine rather than pulling them off. Do not allow any fruits to turn yellow on the vine or the cucumber will stop producing more fruit. Harvest fruits that have matured to a reasonable size regularly to prolong the length of the cropping period.
Sowing time (inside) – February to May
Cutting time – June to September