Keene, NH Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Keene, New Hampshire.
Gardening in Keene
The Elm City sits in the Monadnock Region, where southwestern New Hampshire's relative mildness creates better growing conditions than the state's mountain interior.
Zone 5a with 143 frost-free days. The Ashuelot River valley provides fertile soil. The Monadnock Region is slightly warmer than northern New Hampshire.
Keene's vibrant downtown and the surrounding Monadnock farms create a food-conscious community in the heart of rural New England.
What This Means for Keene Gardeners
The average last spring frost in Keene is around May 8, and the average first fall frost arrives around September 28. That gives you approximately 143 frost-free days to work with.
At 143 days, you're working with a compressed but productive window. Choose varieties by their days-to-maturity number — anything under 75 days is safe, 75-90 requires indoor starting, and 90+ is a calculated risk. The tradeoff: your cool, moderate summers are excellent for crops that heat-zone gardeners struggle with. Your lettuce doesn't bolt in June. Your peas produce for weeks longer. Cool-season crops are your superpower.
These dates are based on NOAA 30-year Climate Normal data for the Keene 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 Keene
With 143 frost-free days, Keene gardeners need to plan strategically — start warm-season crops indoors and choose short-season varieties. Cool-season crops are your strength, thriving in the moderate temperatures that define your growing window. Recommended starting points: kale, lettuce, peas, carrots, potatoes, radishes, garlic, and short-season tomatoes.
See the full New Hampshire planting guide for all 40 plants: New Hampshire Planting Calendar. Or enter your zip code for exact planting dates personalized to Keene.
More About Zone 5A
Keene is in USDA Hardiness Zone 5A, which means average annual extreme minimum temperatures between -20°F to -15°F. View the full Zone 5A planting guide.
See the complete planting calendar for New Hampshire: New Hampshire Planting Calendar.
Other Cities in New Hampshire
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Keene 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 Keene (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Start everything possible indoors — your 143-day season doesn't leave room for a slow start. Direct sow only the fastest, hardiest crops (radishes, lettuce, peas) 3-4 weeks before last frost (May 8). Choose short-season varieties for warm crops. Enter your zip code for exact dates.