The best time to plant cucumbers depends on your growing conditions but generally falls into these guidelines:
- For growing cucumbers indoors in a heated greenhouse, sow seeds from mid-February to mid-March.
- For an unheated greenhouse, polytunnel, or large cold frame, sow in April.
- For outdoor planting, sow cucumber seeds directly in the garden in late May or early June once the soil is warm and risk of frost has passed. Cover with cloches or fleece to keep soil warm.
- Transplant indoor-grown cucumbers to the garden from late May onwards when temperatures are reliably above 12°C (53°F).
- Cucumbers are warm-season plants and do not tolerate frost. Ideal growing soil temperature is at least 65°F (18°C).
- Succession planting every few weeks during the warm season can provide a continuous harvest.
- If starting seeds indoors, begin about 2 weeks before your last expected frost date and transplant after soil warms to about 70°F (21°C).
In summary, outdoor cucumbers should be planted from late May to early June after frost danger has passed and soil is warm, while indoor or greenhouse planting can start earlier in late winter or spring depending on heating conditions.
