Growing zones, or USDA Plant Hardiness Zones, are standard maps used to determine which plants can thrive in specific areas based on average annual extreme minimum winter temperatures. Divided into 13 zones (1–13) and 10°F increments, they help gardeners select suitable perennial plants. In Washington, zones range from 4a to 9a, with higher elevations being colder and coastal areas milder.
Key Aspects of Growing Zones
- Purpose: Zones help determine if a plant is hardy enough to survive the winter in your location.
- Zones 1-13: Zones range from 1 (coldest, -60 F to -50F) to 13(warmest, 60F to 70F)
- Subzones: Each zone is divided into 'a' and 'b' (5°F increments) for higher precision.
- Limitations: Zones do not account for summer heat, soil type, rainfall, or local microclimates.
- Washington Zones: Most of Washington falls between 6a (eastern) and 9a (western).
Ways to Control or Manage Your Zone While you cannot change your official zone, you can manage your local microclimate:
- Greenhouses: Allow for growing warmer, long-season crops in cooler, higher-zone
- Mulch: Protects roots from extreme cold in lower zones.
- Microclimates: Utilize heat-retaining structures like stone walls or windbreaks to protect tender plants.
- Container Gardening: Allows for moving plants to warmer, protected sp ots during winter.
Finding Your Zone
- Use the USDA Plant Hardiness Zone Map with your zip code.
- Check local garden centers for recommendations tailored to your specific area.
