Cucumber cucumber (Cucumis sativus) originates from India and Pakistan: needless to say it is a tender plant, which is generally sown indoors in our regions.
Want to try sowing your own cucumbers this year? Follow our advice in this tutorial dedicated to this refreshingly summery vegetable!
When to sow cucumber?
Every year (it's an annual), in spring! The ideal period is March to April. Cucumber germinates easily between 18 and 22°C, so the interior of an apartment or house is perfect. If your region's climate allows sowing directly outdoors, do so in May.
Where to sow cucumber?
Cucumber's origins and cultural requirements mean that it cannot be sown in the coldest, wettest regions. In northern France favour planting out rather than sowing: sowing is possible, but often disappointing if a warm summer fails to arrive (not to mention powdery mildew problems in rainy areas).
To ensure good germination, sow under cover, indoors, at the same time as sowings of tomatoes, peppers and aubergines.
Then, for planting out, cucumber thrives in:
- Soil: rich in organic matter and humus-bearing, friable, enriched with compost, not too wet or clayey
- Exposure: full sun; cucumber needs warmth
- Companion plants in vegetable patch: broccoli, onions, beans and peas, radishes, cabbages and lettuce. Avoid placing next to tomatoes and potatoes.
Note that cucumber is one of the vegetables that can be grown in a pot, on a well-exposed balcony, in a sufficiently large container fitted with a trellis, and also in raised beds.
How to sow cucumber?
Sow cucumber either in warmth indoors (in most regions), or directly outdoors (in position):
Indoor sowing
You will need:
- Cucumber seeds
- 7–9 cm pots
- Special seed compost or a good potting compost mixed with sand
- Mini greenhouse or transparent cover and cold frame (optional)
- Labels
Steps
- Fill each pot with compost;
- Sow seeds in clusters (3–4 seeds together) in biodegradable pots or reused plastic pots, at 1 cm depth;
- Water and label with sowing date
- Place your pots (or mini greenhouse) near a window;
- Germination takes about 10 days;
- Keep only one plant, the strongest in each pot;
- Prick out under a cold frame or polytunnel from April as soon as plants are large enough, or harden off plants by gradually placing them outside for a few hours a day to acclimatise them to outdoors (bring them back inside at the end of the day);
- Plant out in their final positions in the vegetable patch, every 50 cm, in May (once risk of frost has passed). Previously enrich the soil with compost in spring (apply about 3–4 kg per m²) or with manure in late autumn.
- Mulch around each plant to keep soil cool;
- Care: water regularly (without ever waterlogging soil or wetting leaves) and feed plants with a tomato fertiliser from 15 days after planting;
- Support cucumbers as they grow (using a vertically tied string) so this runner does not keep moisture on its foliage.
Direct sowing outdoors of cucumber
- In May (or June), in soil previously enriched with compost or manure (3 kg/m²), dig 15 cm wide planting holes at 60 cm spacing, add good potting compost;
- Place 3–4 seeds in each hole, 1 cm below soil surface;
- Backfill with sieved soil;
- Thin to two plants per hole as soon as plants have two true leaves;
- Water well, and care as for potted plants, feeding cucumbers throughout summer.
You will harvest from July to September depending on region, timing and sowing technique.
My tip
Sowing cucumbers is worthwhile if you plan to grow around ten plants (for a family of four, two or three plants are generally sufficient).
To optimise space, pair them with companion vegetables such as beans or radishes. Choice of nearby vegetables is important for cucumber. Discover our complete guide to good pairings with cucumber.
Key points for sowing cucumber
- Sow cucumber seeds in clusters, several seeds per planting hole;
- Don't sow too early in spring, cucumber grows quickly and it's better to wait than see seedlings fail;
- Thin to one vigorous plant as soon as first true leaves appear for good development;
- Wait until last frosts have passed in May before planting or transplanting outdoors.
FAQ
Here are questions often asked by beginner vegetable gardeners:
- Why are my cucumber seedlings becoming leggy (too long and fragile)?
This happens if plants lack light or are sown too early indoors. To prevent this, place them near a very bright window (or under a grow light) and sow 3–4 weeks before planting out (not before March–April).
- Why aren't my cucumber plants growing?
Check that ambient temperature isn't too low (below 15°C), that soil isn't waterlogged and that they are not lacking light. Thin to one vigorous plant per pot.
- How to avoid powdery mildew on cucumber leaves?
At planting, space plants for good air circulation, water at the base (not on the leaves), and apply horsetail liquid manure as a preventative.
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