Cucumber: Sowing, planting and harvest calendar
How do you sow cucumbers under cover?
Sow your cucumber under cover about three to four weeks before you can move it to its final growing position. A heated greenhouse allows an earlier start than an unheated structure or an outdoor crop. Avoid sowing too early if you cannot keep seedlings warm and bright: they grow quickly and do not benefit from a long wait in small pots.
Use clean individual pots with drainage holes, filled with light seed compost. Moisten the compost, then sow one seed per pot about 1 to 2 cm deep. Cover it and water gently. Keep the seeds at around 20 to 25 °C with consistent moisture but no standing water. Reusable pots are perfectly suitable.
Seedlings often appear within one to two weeks. Remove any cover as soon as they emerge and give them plenty of light, avoiding excessive heat behind glass. Water without soaking the compost and protect the plants from cold nights. Handle their root balls carefully to preserve the roots. For outdoor planting, harden the seedlings off gradually, then wait until frosts have finished and conditions stay reliably warm, including at night.
How do you sow cucumbers outdoors?
Sow cucumbers outdoors only once frost is no longer a risk and the soil has warmed thoroughly. In a temperate climate this is often late spring or early summer, but a calendar date cannot replace checking night temperatures and soil conditions. Choose a variety suitable for outdoor growing rather than a cucumber intended only for a warm greenhouse.
Prepare a sunny position sheltered from wind, with fertile, well-drained soil. Add well-rotted compost if needed, then loosen the surface. Sow two or three seeds at each growing point, about 1 to 2 cm deep. Water gently and mark the sowing spots so you can find them while waiting for emergence.
Keep the soil moist without saturating it. A cloche or fleece can help plants get started; ventilate on sunny days to prevent overheating. Watch for slugs as soon as seedlings appear. Once they are large enough, cut away weaker seedlings to leave one strong plant without disturbing its roots. Allow space for the variety and chosen support system. If a cover remains until flowering, allow insects access for varieties that need pollination.
How do you plant cucumbers?
Plant your cucumbers once they are well rooted and their final growing position is warm enough. Outdoors, wait until frost risk has passed and temperatures stay reliably above about 12 °C, including at night. An unheated greenhouse can also become too cold. Gradually harden off plants raised under cover, avoiding sudden exposure to wind and strong sunshine.
Choose fertile, well-drained soil in a sunny position sheltered from wind. Prepare it with mature compost if needed. For container growing, use a large pot with drainage holes, at least 30 cm wide and deep, filled with suitable potting compost. Water the nursery pots before removing them and keep each root ball intact: cucumber roots dislike unnecessary handling.
Make a hole the size of the root ball and plant at the same depth, without burying the stem base. Firm gently, then water to settle soil around the roots. Space plants according to the variety and whether you will let them trail or grow vertically. Put supports in place now if you intend to train them upwards. Finish with mulch, leaving the stem clear, and check moisture while the plants establish.
How to care for this plant
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Install plant supports
If you grow this plant vertically, fit a sturdy trellis when planting it out. Guide stems with soft ties and check them as it grows. No support is needed if you let it trail on the ground.
When do you harvest cucumbers?
Harvest your cucumbers when they reach the size suited to their variety, with firm flesh and skin showing their normal colour. A mini cucumber does not need to reach the length of a greenhouse slicing variety. Do not wait for the largest possible fruit: yellowing skin, softness and hardening seeds often mean the best picking stage has passed.
Check plants every two or three days while they are cropping, more often if fruits are growing quickly. Look underneath leaves and near the ground for hidden cucumbers. Support each fruit and cut its stalk with a clean knife or secateurs. Do not tug on the vine, which may snap or come away from its support.
Regular picking encourages further cropping. Remove overgrown fruits too, rather than leaving them to draw resources from the plant. Keep your harvest in the shade and avoid bruising it. Store cucumbers somewhere cool, using the fridge for short storage, and eat them promptly while checking their firmness. Discard any rotting fruit. If you want to pickle them, follow a tested recipe: a jar of plain water is not a method for long-term preservation.
Cucumber
- Type : Vegetables
- Subtype : Fruiting vegetables
- Botanical Family : Cucurbits
Characteristics
- Lifecycle : Annual
- Exposure : Full Sun
- Frost Hardiness : Frost Sensitive
- Cultivation Difficulty : Easy
- Mature height : 30 cm
Sowing & Planting
- Greenhouse crops : Unheated greenhouse
- Greenhouse Growing : Not Required
- Sowing Depth : 2 cm
- Plant Spacing : 60 cm
- Row Spacing : 120 cm
Maintenance
- Maintenance : Moderate
- Water Requirements : High
Other characteristics
- Soil Type : Humus-rich
- Soil pH Preference : Neutral
- Pest Sensitivity : Moderate
- Disease Sensitivity : Moderate
- Weed Sensitivity : Moderate
- Pollination : Insect-pollinated
- Propagation : Sowing