Thompson & Morgan

Important delivery notice
The products on this site are only delivered to UK addresses. If you require delivery to another country please visit one of our other sites below.

how to grow cucumbers

How to grow cucumbers

Savour the taste of summer with your own home grown cucumbers. Cucumbers are an essential ingredient for adding to sandwiches, delicious salads, and those long, cool summer drinks on the patio.

You don’t need a greenhouse to grow them as there are indoor types and outdoor varieties available. But it’s worth checking that you have the right type for your garden before you start sowing. You can grow cucumbers in the ground, in growbags and even in containers. View all of our cucumber seed varieties.

Different types of cucumber

mophead hydrangea

Growing cucumber plants is really quite easy once you understand that there are two main types available, and these need different treatment to produce a good crop. So to keep things simple, here are the main differences between greenhouse and outdoor cucumbers.

Greenhouse cucumbers

If you’re lucky enough to own a greenhouse then it’s well worth growing cucumbers indoors. Greenhouse cucumber plants produce long, smooth fruits similar to those that you find in the supermarkets. Greenhouse varieties don’t need pollinating - in fact, you should remove any male flowers to prevent pollination happening as this produces fruits with a bitter flavour. You can even buy ‘all female’ F1 hybrid varieties such as Cucumber ‘Flamingo’ which only produce female flowers, so you won’t need to worry about male flowers at all!

Outdoor cucumbers

Outdoor varieties are called ridge cucumbers. These varieties tend to be shorter with a rougher skin but have the advantage of being able to crop outdoors, so they are perfect for gardens without a greenhouse. Ridge cucumbers produce male and female flowers, and these need to be pollinated. This is not usually a problem though, as the insects outdoors will do the job for you.

Some ridge cucumbers are suitable for growing in the greenhouse if you prefer, but most gardeners would rather use their precious greenhouse space for greenhouse-type cucumbers. It’s important to never grow ridge cucumbers in the same greenhouse as an ‘all-female’ Greenhouse type as this will lead to cross-pollination, which can produce bitter fruits.

If you’re feeling adventurous you can even try growing white and yellow cucumbers or even ball shaped varieties. Some are ridge cucumbers while others need to be grown in the greenhouse. Always check before you sow them.


Greenhouse Cucumbers Ridge (Outdoor) Cucumbers Unusual Cucumbers
Cucumber 'Tiffany' Cucumber 'Burpless Tasty Green' Cucumber 'Crystal Apple' (Heritage Ridge variety)
Cucumber 'Carmen' Cucumber 'Green Fingers'> Cucumber 'Long White' (Greenhouse variety)
Cucumber 'Delizia' Cucumber 'Masterpiece' Cucumber 'Sunsweet' (Greenhouse variety)

Growing Cucumbers from seed

Whether you are growing indoor or outdoor types you will need to sow Cucumber seeds in a propagator from early March to April. However, outdoor varieties can also be direct sown outdoors from May to June if necessary.

Sow cucumber seed on their sides at a depth of 1cm (½") in 7.5cm (3") pots of free-draining, seed sowing compost. Place the pots in a propagator or seal them inside a plastic bag at a temperature of 20C (68F) until they germinate. This usually only takes 7-10 days.

Once they have germinated you can move them to a bright windowsill and grow them on until they are large enough to be transplanted. Try to maintain a minimum temperature of 15c (60F) and keep the compost moist but not wet. Cucumber seedlings can be prone to scorching so take care to shade them from direct sunlight. When cucumber plants are well grown, you can carefully transplant them, but try to avoid disturbing the roots as Cucumbers resent this.

cucumber staking

How to grow cucumbers in a greenhouse

Greenhouse types can be planted in a warm, humid greenhouse that is kept at a temperature of at least 15c (60F). Plant greenhouse cucumbers at a spacing of 2 plants per grow bag or 45cm (18") apart.

How to grow cucumbers outdoors

Ridge cucumbers should be gradually acclimatised to outdoor conditions over 7-10 days before transplanting into warm, well drained, humus rich soil. Choose a sunny position with shelter from strong winds. When growing cucumbers outdoors they can be planted in single rows at a distance of 90cm (36") apart.

Routine care

When growing cucumbers it is essential to keep them well watered to help your plants establish and to increase crop yields. Feed your cucumber plants with a high potash feed every two weeks once the fruits begin to develop.


greenhouse cucumber

Greenhouse Cucumbers

  • Keep the greenhouse warm and humid by regularly spraying or damping down of pathways. You will probably need to apply some greenhouse shading to protect the plants from scorching.
  • Trailing types will produce higher yields if made to climb. Train the main shoots onto 1.8m (6ft) canes or strings until they reach the top of their support and then pinch out the growing point at the top of the plant. Once the fruit begins to develop, pinch out the end of each side shoot, leaving two leaves after each fruit. This helps to encourage more sideshoots which will produce bigger crops of cucumbers
  • Always remove the male flowers from greenhouse cucumbers. Female cucumber flowers can be identified by a swollen bulge between the bottom of the flower and the flower stem that looks like a tiny cucumber. Male flowers just have a plain stalk so you can easily tell them apart.

Outdoor cucumbers

  • Cucumbers growing outdoors will not need training onto canes - just let them sprawl across the ground.
  • Ridge cucumbers can be pinched out at the main stem after 7 leaves have formed to encourage fruiting side shoots to develop.
  • Outdoor ridge types require pollination by an insect which needs both male and female flowers to be present - do not remove the male flowers from these varieties.

Harvesting cucumbers

You can normally begin to harvest cucumbers around 12 weeks from sowing. Harvesting cucumbers is best done early in the morning when temperatures remain cool. Cut the fruits from the plant using secateurs or a sharp knife. It’s best to harvest cucumbers while they are young and tender, before they show signs of producing seeds, as older fruits can become bitter. Regular harvesting will encourage long continuous production - outdoor types can continue to fruit until September, while greenhouse types can fruit into October if temperatures are warm enough.

  View our special offers