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How to Grow Cucumbers

By The RHS Advice Team

03 Dec, 2025

RHS GYO Guides

• Getting Started
• Choosing What To Grow
• Preparing The Ground
• Sowing
• Planting
• Plant Care
• Harvesting
• Problem Solving

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Getting Started

Cucumbers are tender climbing or scrambling plants, for growing in a greenhouse or a warm sunny site outdoors, either up supports or trailing on the ground. With enough warmth and plenty of moisture, they’ll produce lots of tasty, crunchy, refreshing cucumbers from mid-summer onwards. When trained up supports, they take up little ground space, so can be grown successfully in compact gardens, patio containers or small greenhouses.Cucumbers (Cucumis sativus) are closely related to courgettes, squashes and pumpkins, and are grown in a similar way to their fellow cucurbits, so if you’ve had success with these, you should find cucumbers straightforward too.

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Choosing What To Grow

There are many cucumber varieties to choose from, varying in fruit size, flavour and disease resistance. Small or mini cucumber varieties produce lots of fruits, which are ready to harvest more quickly than longer ones. There are also varieties with tiny fruits (gherkins) for pickling. There are indoor varieties for growing in greenhouses, polytunnels or large coldframes, and outdoor varieties (or ridge cucumbers) for growing in a sunny, sheltered spot. Greenhouse varieties crop for a longer season, from mid-summer through to early autumn. Outdoor varieties are weather dependent, starting to fruit later and finishing earlier, but should still produce a good crop in warm conditions.When choosing, look for varieties that have an RHS Award of Garden Merit (AGM), as these performed well in our trials – see our list of AGM fruit and veg (135kB pdf) and our Recommended Varieties below. You may also find cucumbers growing in the veg areas of the RHS gardens over the summer months, so do visit to compare varieties and pick up growing tips.

What and where to buy

Cucumber seeds are widely available in garden centres and from online suppliers. You can also buy young cucumber plants or plug plants in spring and early summer in garden centres and online. This is often a good option if you only want one or two plants.Grafted cucumber plants have recently become more readily available, mainly from online veg seed/plant suppliers. These are very vigorous plants and should produce a larger crop over a longer season. They are more resistant to soil-borne diseases, so are useful for growing in the same ground (such as a greenhouse border) year after year. However, grafted plants are more expensive and there’s only a limited choice of varieties.

Recommended Varieties

'Carmen' AGM

Greenhouse variety - produces a large crop of long, straight fruits with a good crunch. Good disease resistance.

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‘Emilie’ AGM

Greenhouse variety – gives a plentiful supply of tasty, medium-sized, smooth-skinned cucumbers.

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'Lili' AGM

Greenhouse/outdoor variety – predominantly female flowers. Reliable crop of large, tasty fruits.

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‘Marketmore’ AGM

Outdoor variety – produces a large crop of medium-sized, dark green fruits with a good flavour.

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'Mini Munch' AGM

Greenhouse variety – mini fruits with smooth skin. A heavy cropper over a long season.

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'Delistar' AGM

Greenhouse variety – medium-sized fruits with thin, translucent skin that is easy to digest.

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Preparing The Ground

Cucumbers can be grown indoors in a greenhouse or polytunnel border, or outdoors in a warm, sunny, sheltered spot. Prepare each growing site by digging in two bucketfuls of home-made garden compost or well-rotted manure. Ideally do this a few weeks before sowing or planting, to allow the soil to settle. Alternatively, if you are practising no-dig, mulch the surface of the soil at each site ahead of sowing or planting directly into the mulch. Space your growing sites 30cm (1ft) apart.Cucumbers can also be grown in containers at least 30cm (1ft) wide and deep, filled with peat-free multi-purpose compost.

Related RHS Guides

Organic matterNo-dig gardeningGrowing vegetables in containers

Sowing

Cucumbers are best sown indoors, as they can be started off earlier and will start to fruit sooner. Germination is also more reliable and the seedlings are protected from slugs, snails and poor weather. They should be moved to their final growing position after about a month, once they are growing strongly. Seeds of outdoor varieties can also be sown outside in milder locations, once the soil has warmed up in early summer.

Sowing indoors

Sowing times depend on where you’re ultimately going to grow these tender plants. For growing in a heated greenhouse sow in mid-February to mid-March, for growing in an unheated greenhouse, polytunnel or large coldframe sow in April,and for growing outdoors sow in late April.The process is simple – fill 10cm (4in) pots with peat-free seed compost, water well, then sow one seed in the centre of each, 1–2cm (½–¾in) deep. Ideally position the seeds on their side. Put the pots in a heated propagator at 21°C (70°F) or cover with a clear plastic bag and place on a warm sunny indoor windowsill. Once seedlings appear, after a week or two, remove from the propagator or remove the covering. Continue to keep the young plants warm, in bright light, and watered regularly. For more sowing tips, see our guides below.

Related RHS Guides

Sowing seeds indoors – step by stepUsing peat-free compost for seed sowing

Sowing outdoors

Seeds of outdoor cucumber varieties can be sown directly into their growing position in late May or early June, especially in warmer parts of the UK or if the weather is particularly mild. Prepare your sowing sites in advance (see above) and sow up to three seeds together, 1–2cm (½–¾in) deep, to allow for failures.

If multiple seeds germinate in one site, remove the weaker ones to leave just one strong seedling. After sowing, cover with cloches or plastic-free fleece to keep the soil warm, and leave the covering in place after germination to help the seedlings get off to a strong start. Protect them from slugs and snails, especially in damp weather.

Related RHS Guides

Sowing veg outdoorsSow outdoors – step by step

Planting

Plant indoor-sown or newly bought cucumber plants into their final growing site in late spring or early summer, depending on where they will be growing:

• Greenhouse cucumbers – from late May, plant into a greenhouse border or large pots once the temperature inside is consistently above 12°C (53°F). Or, if you have a heated greenhouse, you can plant as early as late March.
• Outdoor cucumbers – harden off seedlings carefully, to acclimatise them to outdoor conditions, before planting out from early June onwards, once your local temperatures are reliably above 12°C (53°F).

Planting cucumbers is very straightforward – water them well beforehand and try not to disturb the rootball, so they settle in quickly without a check in growth:

• To plant in a container – choose a pot that is at least 30cm (1ft) wide and deep, and fill with peat-free multi-purpose compost. Position one plant in the centre, firm it in gently and water generously, then add suitable supports (see below). Alternatively, plant two cucumbers in a standard-sized growing bag.
• To plant in the ground – plant one cucumber plant into the centre of each prepared growing site (see above), spacing them 30cm (1ft) apart. Firm in gently then water well. Add supports (see below) if you want to train the plants vertically.

Related RHS Guides

Growing veg in containersTransplanting vegetables

Putting up supports

Cucumbers are climbing or scrambling plants that can either be grown up supports or allowed to trail on the ground. Growing them vertically means they take up very little ground space, which is useful in small gardens as well as small greenhouses. It also keeps the fruits clean and away from slugs.Put the supports in place at planting time so their tendrils have something to cling to. The stems need tying in initially, and may need help later if they lose their way or come loose, especially outdoors and when carrying fruit.

The type of support you need depends on where you are growing your plants:

• Greenhouse cucumbers – insert a tall, sturdy bamboo cane that reaches up to the greenhouse roof, or attach a vertical wire or string from the roof, secured at ground level. Horizontal supports may also be required for side-shoots
• Outdoor cucumbers – build a wigwam or other structure from tall bamboo canes, or use stout netting supported vertically on upright stakes. Cucumbers will also climb up trellis or wires attached to a wall or fence.

If you plan to leave your cucumber plants to trail over the ground, it can be helpful to lay plastic-free weed-suppressing membrane over the soil after planting. This helps to keep fruit clean and prevent rotting, and is much easier than protecting each fruit individually when growing small-fruited varieties that crop heavily.

Related RHS Guides

Growing veg vertically

Plant Care

Cucumbers, whether grown outdoors or in a greenhouse or polytunnel, need warmth and a steady supply of moisture to crop well. When grown in containers, plants also benefit from regular feeding.

Watering

Water greenhouse and container plants regularly, especially when fruits are forming, aiming to keep the soil or potting compost evenly moist. During hot spells, they may need watering daily. Outdoor plants growing in the ground should need less regular attention, especially if you mulch the soil, but will still need watering in dry weather in order to grow and crop well.Take care to water at the base of the plants and try not to wet the leaves, as that can encourage fungal diseases such as powdery mildew. Use rainwater from a butt whenever possible, and water at cooler times of the day, ideally in the morning. For more water-wise tips, see our guides below.

Related RHS Guides

Vegetables: wateringCollecting rainwater

Top tip

Sink a plant pot into the ground alongside each cucumber plant and water into it, so the water goes straight down to the roots rather than sitting around the neck of the plant, which can lead to rotting.

Mulching

Lay a thick layer of mulch over the soil around the base of cucumber plants to help hold moisture in the ground, reduce the need for watering, and deter weed germination. Use home-made garden compost or well-rotted manure, but leave a gap around the base of the stem, to prevent rotting.

Related RHS Guides

Mulches and mulchingHow to mulchOrganic matter

Feeding

Cucumbers growing in the ground shouldn’t need feeding, unless the soil is very poor. Plants in containers should be fed every 10–14 days with a general liquid fertiliser. Once they start flowering, change to a high potash liquid fertiliser such as tomato feed, to encourage flowering and fruiting.

Related RHS Guides

Looking after plants in potsChoosing and using fertiliser

Pinching out shoots

It’s a good idea to restrict the vigorous growth of cucumbers, so they concentrate on making fruit rather than growing too large. The method differs depending on where you grow your plants:

• Greenhouse cucumbers – pinch out the growing point when it reaches the greenhouse roof. Also pinch out the tips of side-shoots two leaves beyond a female flower (which has a tiny fruit behind it). Pinch out the tips of flowerless side-shoots once they reach 60cm (2ft) long
• Outdoor cucumbers – pinch out the growing tip once plants have developed seven leaves, to encourage side-shoots. Also pinch out the tips of flowerless side-shoots after seven leaves

Removing male flowers

• Greenhouse cucumbers – most greenhouse varieties are all-female (check seed packets for details), producing almost exclusively female flowers (with a tiny fruit behind them). These must not be pollinated, otherwise the resulting fruits will be bitter. Occasionally male flowers (without a tiny fruit behind them) may appear and need removing
• Outdoor cucumbers – outdoor varieties produce both male and female flowers. The female flowers need to be pollinated in order to produce fruit, so don’t remove the male flowers

Greenhouse heat and humidity

When growing cucumbers in a greenhouse, raise the humidity in hot weather by pouring a full watering can over the concrete floor or central path, so the water evaporates. This helps ensure good growth and even fruit development and deters red spider mites and powdery mildew.Greenhouses can get extremely hot in summer, so put up shading to keep temperatures from becoming damaging, ideally between 18–25°C (64–77°F).

Related RHS Guides

Greenhouse: ventilation and shading

Harvesting

Cucumbers ripen from mid-summer to mid-autumn in a greenhouse, with a shorter season outdoors depending on the weather. Regular harvesting encourages further fruiting.

Fruit size varies according to the variety. In general, mini cucumbers should be picked at about 8cm (3in) long, small-fruited varieties at 15cm (6in) and full-sized varieties at 20–25cm (8–10in). The fruits should be uniformly green and firm, usually with a slightly rounded tip. Cut the stem cleanly with a sharp knife or secateurs, rather than pulling. Fruits can grow rapidly, so check them every few days to get them at their best. If they turn yellowish, bulbous or soft, they are likely to be over ripe.

Problem Solving

Although usually vigorous and fruitful, cucumbers can be weakened by powdery mildew and red spider mites, especially in a greenhouse and if humidity is low. Mildew-resistant varieties are available. Mosaic virus is a more serious problem, and affected plants should be destroyed. See Common problems below for advice on how to spot and tackle these issues.

Related RHS Guides

Controlling problems without chemicalsPreventing problems

Common Problems

Cucumber mosaic virus

Cucumber mosaic virus (CMV) is one of the most common plant viruses, causing yellow mottling, distorted leaves and stunted growth in a wide range of g...

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Glasshouse red spider mite

Glasshouse red spider mite is a common sap-feeding mite that can cause mottled leaves and early leaf loss on a wide range of greenhouse and garden pla...

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Glasshouse whitefly

Glasshouse whitefly is a common sap-feeding insect, mainly of house-plants and greenhouse plants. They excrete a sticky substance (honeydew), which al...

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Powdery mildews

Powdery mildews are a group of related fungi which attack a wide range of plants, causing a white, dusty coating on leaves, stems and flowers.

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Slugs and snails

Slugs and snails are common garden animals, and they are well suited to the damp, mild climate of the UK. A few species feed on garden plants, but mos...

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