What does the term "hardiness zone" refer to in horticulture?

The term "hardiness zone" in horticulture refers specifically to a range of temperatures within which a plant can survive and thrive. This classification helps gardeners and horticulturists determine which plants are most suitable for their local climate conditions. Hardiness zones are primarily based on the average annual minimum winter temperatures, allowing individuals to choose plants that can withstand the expected cold temperatures of their area.

Understanding hardiness zones is crucial for successful gardening and landscaping, as it directly influences plant selection. For example, a plant designated for a zone that experiences milder winters may not survive in a region that falls into a colder zone.

The other options focus on different aspects of plant care and growth requirements, such as sunlight needs, watering schedules, and altitudinal limits, which while important, do not encapsulate the concept of hardiness zones. Hardiness zones take precedence in understanding plant survival in relation to temperature extremes, making it the most relevant definition in this context.