How to grow cucumbers

Cucumbers are hungry, fast-growing plants that thrive in nutrient-rich, moisture-retentive soil. Choose a sunny, sheltered spot protected from cold winds and temperature swings.

Before planting, prepare the soil by digging in plenty of well-rotted compost or organic matter. This helps maintain steady moisture and ensures good root development. A slightly acidic to neutral pH (around 6.5–7) is ideal.

If you’re growing in containers, use a high-quality peat-free compost mixed with a little perlite for better drainage. Adding a slow-release fertiliser or general-purpose organic feed before planting gives your cucumbers the nutrients they need for rapid growth.

For greenhouse crops, many gardeners grow cucumbers in grow bags, inserting two plants per bag and enriching them with compost and feed before planting.

In the UK, cucumber seeds can be started from late March if you have a heated greenhouse or propagator – or April if your greenhouse is unheated.

Sow seeds individually in small pots of seed compost, about 1–2 cm deep, and place them in a warm spot (around 21°C) until germination, which takes 7–10 days.

Once seedlings have developed two true leaves, transplant them into larger pots (8–10 cm) filled with fresh compost, handling the delicate stems gently.

Harden off outdoor-bound plants gradually by placing them outside for longer periods each day once the risk of frost has passed (usually late May to early June).

Greenhouse cucumbers can be planted into their final position once the plants are around 20–25 cm tall and have several healthy leaves. Space plants about 45 cm apart, with good airflow between them. Train them up canes, strings, or trellis to make the most of vertical space.

Outdoor cucumbers prefer a warm, sheltered bed with well-drained soil. Space plants 60 cm apart and protect with fleece or cloches during cool nights.

If growing in pots, choose containers at least 30 cm wide and deep, ensuring excellent drainage. Cucumbers have vigorous root systems and appreciate room to grow.

Cucumbers love warmth, moisture, and consistent feeding. Keep the soil evenly moist at all times, watering at the base to avoid splashing the leaves, which can encourage fungal problems. In hot weather, daily watering may be needed, especially for plants in greenhouses and containers.

Feed plants in containers every 7–10 days with a high-potash liquid fertiliser once flowering begins. This boosts fruit production and overall plant health.

Train plants as they grow, tying stems loosely to supports. Keep greenhouses well ventilated but avoid cold draughts.

Pinch out the growing tip of the plant once it has reached the top of its support to encourage side shoots (and therefore bigger crops) to form. Pinch out the tip of each flowering side shoot once the fruits begin to develop, leaving two leaves after each fruit. You can also pinch out the tips of flowerless side shoots once they reach 60cm long. For outdoor varieties, pinch out the growing tip once seven leaves have formed. You can also pinch out the flowerless tips once the stem has formed seven leaves.

Most greenhouse cucumber 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 varieties are pollinated by insects, so both the male and female flowers are needed to produce fruit.

Watch out for aphids, whitefly, and spider mites, especially under glass. Regular inspection and good airflow help prevent infestations.

If fruits are misshapen, it may be due to poor pollination (for outdoor types). Bitter fruit can result from temperature stress or inconsistent watering. Wilting plants may indicate root rot or overwatering. Always check drainage and avoid letting soil dry completely between waterings.

Cucumbers are typically ready to pick 10–12 weeks after sowing, once they reach a good size and firm texture. Regular harvesting encourages plants to keep producing.

Greenhouse varieties can be harvested when around 20–30 cm long, while outdoor cucumbers are usually shorter and slightly ridged. Don’t let fruits over-mature - they’ll become bitter and tough. Cut cucumbers cleanly from the vine with a sharp knife or scissors to avoid damaging the stem.

From July through September, you’ll enjoy a steady crop of crisp, cool cucumbers. Pick every few days to keep plants productive.

At Fothergill’s, we offer a range of cucumber seeds to choose from, all boasting high germination rates and strong, healthy growth.

With a bit of warmth, steady moisture, and thoughtful care, these vigorous plants can turn even the smallest space into a source of fresh summer produce.

So, roll up your sleeves, sow a few seeds, and look forward to their light, refreshing taste, straight from the vine.

For even more advice, check out our beginners guide to growing from seed.