At a glance
Cucumbers have a reputation for being a greenhouse crop in the UK – and for most of the long, cool varieties grown in British greenhouses, that reputation is deserved. But ridge cucumbers, the outdoor type bred for cooler conditions, are genuinely productive in a UK summer if you give them the warmest spot in the garden, start them off indoors and keep them well-watered. The flavour of a home-grown outdoor cucumber – thicker-skinned, more pronounced taste than the long watery supermarket type – is something most gardeners enjoy once they try it.
Outdoor varieties only – why this matters
This is the most important section. Most cucumber varieties sold in UK garden centres are greenhouse types – long, smooth-skinned fruits that need the warmth and shelter of a glasshouse. Planted outdoors in a British summer they will grow slowly, produce poorly and are very susceptible to cold damage.
Outdoor (ridge) cucumbers are completely different – shorter, often slightly prickly-skinned, hardier and specifically adapted to produce in the cooler, more variable conditions of a UK garden.
| Variety | Fruit type | Key trait | Best for |
|---|---|---|---|
| Marketmore | Dark green, 20cm | Classic outdoor variety, reliable in UK conditions, good disease resistance | General outdoor growing anywhere in UK |
| Bush Champion | Mid-green, 20cm | Compact bush habit – ideal for raised beds and small gardens, no trailing | Small gardens and raised beds |
| Crystal Lemon | Round, pale yellow | Unusual fruit, mild sweet flavour, very productive outdoors | Novelty, excellent flavour |
| Burpless Tasty Green | Dark green, slim | Fewer seeds, mild flavour, easier to digest than most varieties | Slicing and fresh eating |
| Marketmore 76 | Dark green, 20-22cm | Improved Marketmore with better mildew resistance – good for wetter UK summers | Wet climates and northern UK |
Check the seed packet for “outdoor” or “ridge” before buying. The distinction between indoor (greenhouse) and outdoor (ridge) cucumbers is not always prominently labelled. Look for the word “outdoor”, “ridge” or “suitable for outdoors” on the packet. If it just says “cucumber” with no further qualifier, assume it is a greenhouse type.
Sowing and planting out
- 1Sow indoors in April Sow one seed per 9cm pot, 2cm deep, on its side (this prevents the seed case rotting on the flat end). Keep at 20-25°C – cucumbers need warmth to germinate well. A heated propagator is ideal. Germination takes 5-7 days in warm conditions.
- 2Harden off for two weeks from late May Cucumber plants are sensitive to cold and wind. A full two weeks of hardening off is important – outside during the day, inside at night. Plants put out without hardening off show signs of stress for weeks.
- 3Plant out after the last frost in the warmest spot available South or south-west facing beds, against a south-facing wall or fence, or in the sunniest corner of the garden. In north England and Scotland, a south-facing wall that reflects and retains heat makes the difference between a good crop and a disappointing one.
- 4Space at 45-60cm Trailing varieties need 60cm in all directions. Bush varieties can be closer at 45cm. Incorporate a generous amount of garden compost or well-rotted manure into the planting hole – cucumbers are hungry plants.
Training and support
Trailing outdoor cucumber varieties can be left to sprawl across the ground or trained up a support structure. Training upward has significant advantages in a UK garden: it improves airflow (reducing mildew risk), keeps fruits off the wet soil (preventing rot), makes harvesting easier and takes up less ground space.
A simple framework of bamboo canes tied at the top with horizontal canes across, or a section of wire mesh attached to a fence, works well. The plants attach themselves with tendrils and need only occasional tying in. Bush varieties need no support and are excellent in raised beds where their compact habit fills the space without sprawling.
Pollination – different rules to indoor types
Unlike greenhouse cucumber varieties (which must not be pollinated to avoid bitter seeds), outdoor ridge cucumbers require pollination to set fruit. They produce separate male and female flowers on the same plant – female flowers have a tiny immature cucumber behind the petals, male flowers have a plain stem.
In a normal UK summer with regular bee activity, pollination happens naturally without any intervention. In cold, wet spells when bees are not active, you can hand-pollinate by picking a fully open male flower and rubbing it gently inside a fully open female flower. This takes seconds and reliably solves poor fruit set in difficult weather.
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Watering and feeding
Cucumbers are one of the thirstiest crops in the vegetable garden. The large fruits are over 95% water and that water has to come from somewhere. Inconsistent watering causes bitterness in the fruits and is the most common reason outdoor cucumbers disappoint. Water deeply and consistently at the base – never overhead – two to three times per week in dry weather.
Begin feeding with a high-potash liquid feed every 7-10 days once the first fruits start to swell. Before fruiting, a balanced general fertiliser or liquid seaweed is fine. A mulch of compost around the base of each plant conserves moisture significantly and reduces watering frequency.
Powdery mildew is almost inevitable by late summer. Outdoor cucumbers develop powdery mildew on older leaves from August onwards in most UK gardens – it is a natural part of the plant ageing. Remove affected leaves promptly and the plant will continue producing. Only abandon the plant if mildew reaches the young growth at the growing tips before a reasonable harvest has been achieved.
Harvesting for continued production
Harvest cucumbers before they reach full size – outdoor ridge cucumbers are at their best at around 15-20cm long when the skin is still dark and the seeds are small. Overripe cucumbers become yellow, seedy and bitter. Cut rather than pull to avoid damaging the stem, leaving a short section of stalk attached.
Pick every two to three days at peak production. Like courgettes, leaving fruits on the plant too long signals to it that reproduction is complete and slows new fruit production. Regular harvesting keeps the plant producing right through to the first autumn frosts. For more on planning your raised bed for maximum productivity through the season, read our what to plant in a raised bed UK guide.
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