How to grow cucumbers and best varieties

Cucumbers are relatively easy to grow, either in an unheated greenhouse or in a sunny spot outside. You can even grow some varieties in a hanging basket.

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Best cucumber varieties

Full testing results for cucumbers

Which? members can log in now to see the full results and detailed reviews of our Best Buy varieties. If you’re not a member, join Which? to get instant access.

Snack-size cucumbers

USING THE TABLE Mini cucumbers 8-12cm; half-size 15-20cm OVERALL RATING Ignores price and is based on yield per plant 25%; number of fruits per plant 25%;taste 30%; resistance to powdery mildew 10%; ease of picking 5%; length of harvest 5%.

Outdoor cucumbers

Using the table Length, width and weight of fruit Averages of several typical fruits. Fruits per plant and total yield Average of five plants. Overall rating Takes into account taste and texture, and smoothness, thickness and appearance of skin.

How we test cucumbers

We grew different varieties of cucumbers and harvested fruits two to three times a week, recording the number and weight of cucumbers for each variety and rating them for quality. We also rated the varieties for ease of picking, flavour and whether they succumbed to powdery mildew.

When to sow

Sow cucumbers for growing in greenhouses or polytunnels from mid- to late April, or up to mid-May in the North. For cucumbers for growing outdoors, sow in mid- to late May.

Use 5cm pots or large modules and sow singly into a Best Buy compost for sowing seeds. Seeds need to beat 20°C or more for germination; sow in a greenhouse, in a heated propagator or on a windowsill indoors. Pot on into a Best Buy compost for raising young plants once seedlings have their first true leaves, and keep warm until they have about five leaves. Be careful not to overwater them or the plants can rot and die.

Caring for your plants

Planting indoors

Plant into growing bags or pots (10L-plus in size) of Best Buy compost for containers mixed with a Best Buy controlled-release feed in a greenhouse or polytunnel and train as cordons up supports or strings tied to the greenhouse frame. Pinch out side-shoots as the plants grow, and allow the plants to trail downwards once they reach the top of the supports.

Planting outdoors

Outdoor cucumbers can be planted in a sunny spot outside once the danger of frost has passed in late May or early June.

Growing in a hanging basket

New breeding has produced small cucumber plants that are suitable for growing in hanging baskets. Put one plant per 30cm basket, using a Best Buy compost for containers mixed with a Best Buy controlled-release feed. Hang up the basket in a sunny spot outdoors and let the tendrils hang down without bothering to support them. The fruit are easy to find and should be picked when they're about 10cm long.

Watering and feeding

Keep well watered – cucumbers are thirsty – and feed with a liquid fertiliser, such as tomato feed, if you didn’t incorporate a controlled-release feed into the compost at planting time.

Outdoor plants

Outdoor cucumbers need very little attention. After transplanting you may want to cover plants with fleece, if there are still some cold winds. Keep the area weed free and watch for the first fruits from late July. Once fruiting begins and if afternoon temperatures are above 22C, you can expect five fruits or more every week, mainly in August.

How and when to harvest

Harvest in: July to October

Pick cucumbers before you see any decrease of dark green in the colour. Paler skin suggests seed development, with flesh becoming harder and less sweet. Regular picking encourages development of more fruits, so it's worth checking every day undercover and every two days outside.

Outdoor cucumbers usually finishing cropping in September, but indoor plants carry on until early October.

Common growing problems

Powdery mildew

Powdery mildew is the main problem to watch out for. Remove affected leaves, don’t overcrowd plants, ensure they’re well watered and avoid wetting the leaves when you water.

Read more about powdery mildew.

Red spider mite

Red spider mites can cause speckled and yellowing leaves; watch out for the fine webbing they produce, too. They can be controlled with a biological control, such as phytoseiulus or amblyseius. These predatory mites will feed on the pest and deal with the problem for you. 

Read more about red spider mite.