How to Grow Cucumbers: A Complete Guide
Cucumbers are one of the most rewarding vegetables to grow at home, whether you have a spacious garden, a greenhouse, or just a sunny balcony. With the right care, a single plant can produce an impressive harvest throughout summer and into early autumn. This guide covers everything you need to know about growing cucumbers successfully.
Choosing the Right Cucumber Variety
Before you start, it is worth deciding where your cucumbers will grow because this determines which varieties will perform best.
Outdoor ridge cucumbers are hardier and more tolerant of cooler conditions. Good varieties include ‘Marketmore’, ‘Bush’, ‘Crystal Apple’, and ‘Lemon’. These are ideal if you do not have a greenhouse and want to grow plants directly in your garden or allotment.
Greenhouse cucumbers need warmer conditions and prefer protected cultivation. ‘Cortez’, ‘Bella’, and ‘Shooting’ are reliable choices. Look for all-female varieties for the best yields, as they do not need pollination and will produce fruit without any male flowers getting in the way.
If you are short on space, mini cucumbers such as ‘Pickleteez’ and ‘Lilian’ are compact plants that crop well in containers. For pickling, gherkin varieties like ‘Venlo’ and ‘Parisian’ are bred specifically for producing small, firm fruits perfect for jars.
Soil Preparation and Growing Conditions
Cucumbers grow best in temperatures above 20C with a minimum soil temperature of 15C for planting out. The soil should have a pH between 6.0 and 7.0, and it must be rich in organic matter and well drained.
Prepare the ground by digging in plenty of compost or well-rotted manure several weeks before planting. If you are planting outdoor cucumbers, warming the soil beforehand helps significantly. Cover the soil with black plastic mulch or cloches two weeks before planting to raise the temperature.
Avoid planting cucumbers where cucurbits have grown recently. Courgettes, marrows, pumpkins, and other cucumbers all belong to the same plant family and will have left behind soil conditions that the new plants find challenging.
Sowing and Planting
Greenhouse varieties can be sown from February to March in pots of seed compost. Sow seeds on their side about 1-2cm deep in 7cm pots and keep them at 18-21C. Germination typically takes 5-10 days. Plant the seedlings in the greenhouse from April to May.
Outdoor varieties should be sown indoors from April to May using the same method. Transplant them to their final growing position in June once the soil has warmed and all risk of frost has passed. In milder areas, you can direct sow seeds outdoors in May or June under cloches for protection.
Whatever variety you choose, never plant out while frost risk remains. Cucumber seedlings are tender and will not tolerate cold nights.
Spacing
Give plants enough room to grow and good airflow to stay healthy:
- Greenhouse plants: 45-60cm apart, trained up strings or stakes
- Outdoor ridge plants: 90cm between plants, 120cm between rows
- Containers: minimum 30cm pot, one plant per pot
Watering and Feeding
Cucumber plants need consistent moisture but hate sitting in waterlogged compost. Water little and often, keeping the compost evenly moist at all times. Never let plants wilt from drought. Increase watering dramatically once the fruits begin to swell, and always use tepid water rather than cold tap water straight from the mains.
Once flowers first appear, start feeding with a high-potassium liquid fertiliser such as tomato feed. Continue every 10-14 days once fruits are forming. This makes a significant difference to the size and quality of your harvest.
Training and Pinching
Training cucumber plants properly keeps them manageable and maximises yields. Pinch out the growing tip once the main stem has produced 7-8 leaves to encourage side shoots to develop. In greenhouse cultivation, train a single stem upward and remove all side shoots below the first fruit to direct energy into fruit production.
For outdoor ridge cucumbers, allow side shoots to develop and trail along the ground. Mulch around the base of outdoor plants to keep roots cool and retain moisture in hot weather.
Greenhouse cucumbers appreciate shading during peak summer to prevent the foliage overheating. A simple shade paint or netting over the glass works well.
Common Pests and Problems
Aphids are the most common pest and can be tackled with a strong jet of water to dislodge them, biological control using lacewing larvae, or insecticidal soap. Do not let them build up because they also spread viral diseases.
Red spider mite thrives in dry greenhouse conditions. Increase humidity by damping down pathways regularly. Biological control with the predatory mite Phytoseiulus is highly effective and widely available.
Whitefly can be controlled with yellow sticky traps and biological control using the Encarsia wasp. Check traps weekly so you catch an infestation early.
Slugs and snails target young seedlings. Beer traps and copper tape around pots are effective deterrents.
Several diseases can affect cucumbers. Powdery mildew appears as a white coating on leaves and is encouraged by poor air circulation. Remove affected leaves promptly and improve ventilation. Downy mildew causes yellow patches on leaves and spreads in damp conditions. Again, remove affected leaves and avoid wetting the foliage when watering.
Cucumber mosaic virus causes mottled leaves and distorted growth. There is no cure, so control aphid populations to prevent it spreading and remove affected plants immediately.
Root rot is almost always caused by overwatering or poor drainage. Make sure containers have drainage holes and that outdoor beds are not sitting wet.
Harvesting
Cucumbers are usually ready to harvest 8-12 weeks after planting, depending on the variety. Pick fruits when they are firm, green, and at the size specified for your variety. Do not allow cucumbers to turn yellow on the plant because this signals they are overripe and will taste bitter.
Harvest little and often, every 2-3 days if possible, to encourage the plant to keep producing. Use a sharp knife to cut fruits from the plant rather than pulling them. The best time to harvest is in the morning when the fruits are at their crispest. Remove any damaged or malformed fruits promptly to keep the plant productive.
Storage
Fresh cucumbers keep well in the refrigerator for up to a week if stored unwashed in a plastic bag. They do not freeze well and are best eaten soon after harvest.
If you have grown gherkin varieties, you can pickle the small fruits in vinegar for longer storage. Keep cucumbers away from apples, pears, and tomatoes in storage because these fruits produce ethylene gas that causes cucumbers to soften prematurely.
Summary
Growing cucumbers is straightforward when you match the variety to your growing space, warm the soil before planting, and keep on top of watering and feeding. Regular harvesting keeps plants productive and means you can enjoy fresh cucumbers from your own garden for weeks on end.
