How to grow cucumbers

Inspired by a helpful YouTube guide. This walk-through is based on the GrowVeg video "Growing Cucumbers From Sowing to Harvest", from the UK-based GrowVeg channel. It covers indoor and outdoor varieties side by side, which is useful if you are still deciding where to grow them.

1. Decide on indoor or outdoor varieties

Indoor cucumbers (greenhouse types) produce long, smooth fruits and crop more heavily in the UK climate. Outdoor or ridge cucumbers are shorter, slightly bumpier, and far more tolerant of cool summers.

If you have a greenhouse or polytunnel, go indoor. If you are growing entirely outside in Kent, a ridge variety like ‘Marketmore’ or ‘Burpless Tasty Green’ will give you better results than fighting the wrong type.

2. Start seeds indoors in April

Sow seeds on their side in small pots of seed compost, about 1 cm deep. Cucumbers germinate best at 20–25°C, so a propagator or warm windowsill is ideal. They should be up within a week.

Do not sow too early. April is about right for most of the UK. Cucumber seedlings grow fast and can get leggy quickly if they are waiting around for warm enough outdoor temperatures.

3. Pot on as plants grow

Move seedlings into larger pots once they have two or three true leaves. Keep them in a warm, light spot - a cold windowsill will slow them down noticeably.

Harden off outdoor varieties in late May and early June by putting them outside during the day and bringing them in at night. Do not rush this. A cold snap can set plants back weeks.

4. Plant out when the weather is settled

For outdoor varieties, plant into the ground or large containers once night temperatures are consistently above 10°C - usually late May to early June in Kent. Space plants 60–90 cm apart and give them canes, netting, or a trellis to climb.

Greenhouse varieties go into their final position a little earlier, once the greenhouse is warm enough. Grow bags or large pots of good compost work well.

5. Train plants upwards

Pinch out the growing tip once the main stem reaches the top of its support. This encourages side shoots, which is where the fruit forms. For indoor types, remove female flowers (the ones with a tiny fruit behind the petals) on the bottom 60 cm of stem to stop early fruits.

That said, outdoor ridge cucumbers can largely be left to sprawl on the ground if space allows - they are less fussy about training than the greenhouse types.

6. Water and feed consistently

Cucumbers are thirsty. Water little and often rather than in occasional heavy doses - irregular watering causes fruits to taste bitter and can lead to blossom end problems.

Start feeding with a high-potassium liquid feed (tomato fertiliser works perfectly) once flowers appear, roughly every two weeks. Keep it going throughout the cropping season.

7. Harvest before fruits get too large

Pick cucumbers when they reach a useable size and are still firm. Most varieties are best at 15–20 cm. If you leave them to grow enormous and yellow, the plant slows down production.

Regular harvesting keeps the plants going. A well-watered, well-fed plant in a good summer can produce fruit for two or three months without much effort.

When to call a handyman

If you want raised beds built, a grow-house assembled, or trellis and netting supports fitted, that is all solid handyman work. Richard covers garden construction jobs across Sandwich and Kent - get in touch if the practical side is more than you want to tackle alone.