Growing season
The part of the year when environmental conditions permit plant growth, often bounded by temperatures too low for active growth.
Growing degree day: A measure of accumulated warmth above a chosen temperature threshold, used to estimate plant development. Accumulated warmth helps quantify how quickly crops progress within the season.
Plant hardiness zone: A geographic classification based chiefly on the average annual extreme minimum temperature. Hardiness zones guide plant selection, but do not directly specify the length of the growing season.
Growing season lengthening: An observed or projected increase in the duration of periods suitable for plant growth. Warming has lengthened growing seasons in many regions, with uneven ecological and agricultural effects.
Growing season temperature: The average temperature measured over a defined period of plant growth. Thermal conditions influence growth rates and determine which crops can mature locally.
Köppen climate classification: A system that classifies climates using temperature, precipitation, and seasonal patterns of vegetation. Its climate boundaries provide a broad framework, not a direct measure of local growing-season dates.
Frost date: The calendar date on which a location experiences a specified threshold of freezing temperature. The last spring frost and first autumn frost often bound the frost-sensitive growing period.
Crop calendar: A schedule of agricultural activities, including planting, cultivation, and harvest. Its timing must fit the local window for crop growth and maturation.
Phenology: The study of recurring biological events and their timing in relation to environmental conditions. Season shifts change the timing of leaf-out, flowering, migration, and other seasonal events.
Last frost date: The date of the final spring occurrence of a specified freezing temperature at a location. It often marks the earliest safe planting time for frost-sensitive crops.
Climate change attribution: The process of determining how much observed climate change results from human influence or natural variability. Attribution helps distinguish the causes of observed shifts in season length.