In Ukraine, especially in Ternopil, Ternopil Oblast, you should plant cucumbers outdoors when the risk of late frosts has definitely passed and the soil has warmed up sufficiently.

As a general guideline, this is usually mid- to late May.

Here are some important factors to consider:

Soil temperature: The soil temperature should ideally be at least 12-15°C before planting cucumber seedlings outdoors. Colder soils can slow plant growth and make them more susceptible to disease.
Air temperature: Nighttime temperatures should also be consistently above 10°C. Frosts can easily damage or even kill young cucumber plants.
Last frost date: Keep a close eye on weather forecasts and find out the average last frost date in your area. In Ukraine, this can vary depending on the region.
Indoor Start-up: To advance the harvest, you can start cucumbers indoors about 3-4 weeks before the expected planting date. The young plants will then be more robust when they are moved outdoors.
Specific recommendations for Ternopil in spring 2025:

Since we are in April 2025, we cannot yet predict the exact weather conditions in May. It is advisable to closely monitor local weather forecasts and long-term forecasts for May 2025.

In general, I would consider the following periods for outdoor planting of cucumbers in Ternopil:

From mid-May: When the weather is consistently warm and there is no longer any risk of frost.

End of May: As a safer option to minimize the risk of late frosts.
Additional tips:

Hardening off: If you’ve grown young plants indoors, gradually acclimatize them to outdoor conditions (wind, sun, cooler temperatures) about a week before planting.

Protected location: Choose a sunny, wind-protected location for your cucumbers.

Soil preparation: Loosen the soil well and enrich it with compost or other organic matter.
Keep an eye on the weather, and you’ll find the optimal time to plant your cucumbers outdoors in Ternopil in spring 2025!