Kasvukausia

Kasvukausia is the plural form of kasvukausi, a Finnish term meaning the growing season. It denotes the portion of the year during which conditions are suitable for active plant growth, primarily determined by temperature, daylight and moisture.

The start is commonly defined as the period when average daily air temperature remains above a threshold (often around +5 °C) for a sustained period, reducing frost risk and enabling growth. Some definitions also consider soil temperature. The season ends when temperatures fall below the threshold or when adverse conditions reduce growth. The length of kasvukausi varies with latitude, altitude and local climate, and is typically longer in southern regions and shorter in northern areas.

To quantify kasvukausi, measures such as growing degree days (GDD) or other heat-unit indices are used. These help in planning sowing, planting, irrigation and harvest schedules, as well as in forestry and ecological assessments where active growth periods are relevant.

In the context of climate change, kasvukausi can shift in time and length, reflecting changes in temperature and precipitation patterns. In controlled environments like greenhouses, the effective kasvukausi can be extended or shortened through artificial heating, cooling and lighting.