Cucumbers are thirsty, warmth-loving climbers that reward you with a heavy crop from just a plant or two — provided you start them warm, keep them watered, and choose the right type for where you will grow them. The single most important early decision is greenhouse type versus outdoor type, because they are pollinated and handled quite differently.
Two types: greenhouse and outdoor
Modern greenhouse (all-female) cucumbers produce smooth, long fruit and set without pollination — in fact their fruit must not be pollinated, or it turns bitter and misshapen, so any male flowers should be removed. Outdoor or ridge cucumbers are tougher, shorter and knobblier, and they do need insect pollination, so their male and female flowers should both be left alone. Check which type you have before you start pinching off flowers, because the rules are opposite.
Sowing from seed
Sow indoors in warmth in mid-spring, or a little later for outdoor types. Cucumber seed germinates fast in warmth but rots in cold, wet compost, so provide steady warmth — ideally bottom heat — and keep the mix just moist. A classic tip is to sow the flat seeds on their edge, which is said to help water run off and reduce rotting. Give seedlings strong light so they do not stretch, and pot on as they grow.
Planting out and where to grow
Cucumbers hate root disturbance and cold, so transplant carefully and only once frost has passed and it is warm. Greenhouse types crop best under cover in cool climates; outdoor ridge types can go into a warm, sheltered, sunny bed or large container once hardened off. Rich, moisture-retentive soil or a big pot of good compost gets them off to a strong start.
Support and training
Most cucumbers climb happily, saving space and keeping fruit clean and straight. Train the main stem up a cane, string or netting, and pinch out the growing tip once it reaches the top of its support to encourage fruiting side-shoots. Outdoor trailing types can also be left to scramble along the ground.
Watering, humidity and feeding
Cucumbers are mostly water and need a lot of it: keep the soil consistently moist, never letting it dry out, as drought stress is a direct cause of bitter fruit. Water at the base to keep foliage dry, and in a greenhouse a humid, warm atmosphere suits them. Once fruiting starts, feed regularly with a high-potassium feed to sustain the heavy crop (see fertilizing).
Common problems
Bitter fruit comes from irregular watering, heat stress or (on all-female types) accidental pollination. Powdery mildew — white coating on leaves — is common late in the season in dry-root, humid-air conditions; keep plants watered and airy (see powdery mildew). Poor fruit set on outdoor types means too few pollinators or cold weather (see flowering but not fruiting). Collapsing seedlings at the base are damping-off.
Harvesting
Pick cucumbers young and often, while the skin is smooth and the fruit is firm — regular picking keeps the plant producing, whereas leaving fruit to grow large and yellow tells it to stop. Cut rather than pull the fruit, and check plants every couple of days at the height of the season.
Choosing a variety
Beyond the greenhouse-versus-outdoor split, there is plenty of choice within each group. All-female F1 greenhouse varieties are the most productive under cover and remove the worry of bitter, pollinated fruit because they set none of the male flowers that cause it. Outdoor ridge types are hardier and quicker to crop in a short summer. There are also mini or “snack” cucumbers that crop heavily in small spaces, and gherkin types bred specifically for pickling. If you garden without a greenhouse, choosing a dedicated outdoor variety rather than a greenhouse one makes a real difference to success, because outdoor types are bred to tolerate cooler, more variable conditions.
Greenhouse care through the season
Under cover, cucumbers enjoy warmth and humidity but hate stagnant, baking air. Damp down the greenhouse floor on hot days to raise humidity and keep the temperature from spiking, ventilate to prevent the scorching heat that stresses plants, and provide light shade in the fiercest midsummer sun. Train the main stem up its support, pinch out the tip at the top, and remove the lowest fruits and any yellowing leaves to keep air moving around the base — good airflow is the best defence against the powdery mildew that so often ends a greenhouse crop early.
Growing cucumbers in containers
Cucumbers grow well in large pots, grow-bags and even sturdy hanging baskets for compact types, which suits a patio, balcony or small greenhouse. Use a big container of rich, moisture-retentive compost, because the limiting factor is almost always water — a pot that dries out will give bitter, misshapen fruit. Provide a cane, trellis or netting for the plant to climb, feed weekly once fruiting begins, and never let the compost dry out in warm weather. A single healthy plant in a large container can keep a household in cucumbers through summer.
Related guides
Part of our Vegetable Gardening guides.
- Seed germination & starting seeds
- Damping-off in seedlings
- Powdery mildew
- Vegetables for a greenhouse
- Growing bitter melon (a trellised cucurbit)
For guidance on choosing the right feed, see our fertilizer guide.
