Kennewick, WA Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Kennewick, Washington.
Gardening in Kennewick
The Tri-Cities' agricultural heart sits where the Columbia, Snake, and Yakima Rivers converge — Eastern Washington's most concentrated agricultural area.
Zone 7a with 193 frost-free days. The river confluence provides irrigation and valley warmth. The surrounding Columbia Basin agriculture proves these conditions grow food at a world-class level.
The Tri-Cities' wine and agricultural industries demonstrate the desert's potential when irrigated. Home gardeners share those conditions.
What This Means for Kennewick Gardeners
The average last spring frost in Kennewick is around April 10, and the average first fall frost arrives around October 20. That gives you approximately 193 frost-free days to work with.
A solid, workable season. Most standard vegetable varieties have enough time to mature, though the longest-season crops (like sweet potatoes at 90+ days or large watermelons at 85+ days) need to be started early and chosen carefully. Indoor seed starting isn't optional — it's how you buy the extra weeks that make the difference between a good harvest and a great one.
These dates are based on NOAA 30-year Climate Normal data for the Kennewick area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Kennewick
Kennewick's 193-day season gives you plenty of time for most vegetables with good planning. Start warm-season crops indoors to maximize your window. Cool-season crops thrive in your spring and fall shoulder seasons. Recommended starting points: tomatoes, peppers, lettuce, carrots, beans, broccoli, garlic, and basil.
See the full Washington planting guide for all 40 plants: Washington Planting Calendar. Or enter your zip code for exact planting dates personalized to Kennewick.
More About Zone 7A
Kennewick is in USDA Hardiness Zone 7A, which means average annual extreme minimum temperatures between 0°F to 5°F. View the full Zone 7A planting guide.
See the complete planting calendar for Washington: Washington Planting Calendar.
Other Cities in Washington
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Kennewick area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Kennewick (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Start warm-season seeds indoors 6-8 weeks before your last frost (April 10) to maximize your 193-day window. Direct sow cold-hardy crops like peas and lettuce 3-4 weeks before last frost. Every week of early indoor starting matters at this season length. Enter your zip code for exact dates.