How to grow cucumbers

Cucumber seeds are widely available in garden centres and from online suppliers.

You can usually buy young cucumber plants or

Seedlings or young plants grown singly in small modules, with the advantage that they can be transplanted with minimal root disturbance. Bedding plants and young veg plants are often sold as plug plants of various sizes, with smaller ones requiring more aftercare. They usually need to be potted up and grown on indoors until large enough to plant outside.

• Mid-February to mid-March – if you’ll be growing them in a heated greenhouse 

• April – if they’ll be growing in an unheated greenhouse, polytunnel or large cold frame

• Late April – for growing outdoors 

Fill 10cm (4in) pots with seed compost, water well, then sow one seed in the centre of each, 1–2cm (½–¾in) deep. Position the seeds on their side to prevent rotting.

Place the pots in a

A heated propagator is a portable heated structure with a vented lid and adjustable, constant, thermostatic temperature control. It provides a warm, humid environment to help seeds germinate and cuttings to root quickly.

A propagator is a portable, lightweight structure usually plastic, with a vented or unvented lid to provide a humid, slightly warmer atmosphere. It is useful to help seeds germinate and root cuttings. It may have adjustable, thermostatic temperature control.

propagator

A seedling is a young plant grown from seed.

seedlings

• Reliably warm conditions, which should lead to better germination.

• Keeps the seedlings out of reach of slugs and snails.

• Protects seedlings from poor weather.

Seeds of outdoor cucumber varieties can be sown directly in their growing site in late May or early June, especially in milder parts of the UK or if the weather is particularly warm. They should be protected with cloches or fleece.

Prepare the ground as detailed above, then sow the seeds 1–2cm (½–¾in) deep and 30cm (1ft) apart. You can sow up to three seeds together in each spot, to allow for failures, then if several germinate, remove the weaker ones to leave just one strong seedling at each spacing.

Cover the sowings with cloches or

A soft, fibrous, translucent material laid over or around plants hastening their growth and protecting them against weather and pests. Heavier grades of fleece give about 2°C of protection from frost. It is usually used without supporting hoops.

Germination is the process by which a seed develops into a new plant. It starts with the seed coat absorbing water, expanding and splitting, which allows oxygen and water into the seed so its food reserves can be broken down and used by the embryo for growth. The first root (called the radicle) pushes into the soil to anchor the new plant in place and start absorbing water and nutrients. The first shoot (called the plumule) then grows upwards, out of the soil, towards the light.

germination

A seedling is a young plant grown from seed.

seedlings

Twine is a soft, fine loosely woven string treated with preservatives for outdoor use. Used for tying in climbers and other plants to supports.

twine

• With greenhouse cucumbers – insert a tall, sturdy bamboo

  A cane is a slender, straight, length of woody plant material, usually bamboo. Canes are primarily used as plant supports. The fruiting stems of blackberries, raspberries and hybrid berries (such as loganberries and tayberries) are also known as canes, so these crops are often referred to as cane fruit.

  cane 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. 

• With 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 leave outdoor cucumbers to trail over the ground, it’s best to lay weed-suppressing membrane or black plastic over the soil, to deter weeds. And do bear in mind that the plants and fruit are more vulnerable to pests such as slugs on the ground.

Water little and often, to keep the potting

Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

Feed cucumber plants in containers every 10–14 days with a general liquid fertiliser.

Once they start flowering, change to a weekly tomato feed, to encourage flowering and fruiting.

It’s a good ideal to restrict the vigorous growth of cucumbers, so they concentrate on making fruit rather than growing too large:

• With greenhouse cucumbers,

  Removal of a plant’s growing tip (usually with finger and thumb) to encourage it to produce side-shoots, forming a bushier, well-shaped plant that will bear more flowers and/or fruits.

  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. 

• With 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.

• 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, in which case remove them. 

• Outdoor cucumber plants 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.

In greenhouses, raise the

The concentration of water vapour in the atmosphere. This affects the rate at which plants transpire (lose water from their leaf pores), which in turn affects how much water their roots absorb from the soil. If air humidity is low, plants transpire quickly and become at risk of wilting if water is lost from the leaves faster than it can be absorbed by the roots. Different plants require different levels of humidity to thrive. Many tropical houseplants need high humidity and are best grown in a steamy bathroom, misted regularly or placed on a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor or overhead misting.