Mitchell Caverns, CA Frost Dates & Growing Season

The two dates every Mitchell Caverns garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Mar 6
~50% chance of frost after
First fall frost
Dec 8
~50% chance of frost before
Growing season
277 days
frost-free stretch
USDA zone
≈ 9a
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Jan 17 Mar 6 Apr 9
First fall frost Jan 5 Dec 8 Nov 12
Hard freeze (28°F), median last Feb 1 · first Dec 25

Computed from NOAA 1991–2020 climate normals at the MITCHELL CAVERNS station. "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Mitchell Caverns

Computed from Mitchell Caverns's own frost dates. Click any crop for the full zone-9 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Jan 9 – Jan 23 Mar 13 – Mar 20
🫑 Peppers Dec 26 – Jan 9 Mar 20 – Mar 27
🥬 Lettuce Jan 23 – Feb 6 Feb 6 – Feb 20 Feb 6 – Mar 6
🫛 Peas Jan 23 – Feb 6
🥕 Carrots Feb 13 – Mar 6
🥦 Broccoli Jan 16 – Jan 30 Feb 13 – Feb 27
🥬 Kale Jan 23 – Feb 6 Feb 6 – Feb 20 Feb 6 – Feb 20
🥒 Cucumbers Feb 6 – Feb 13 Mar 13 – Mar 20 Mar 13 – Mar 20
🥒 Zucchini Feb 6 – Feb 13 Mar 13 – Mar 20 Mar 13 – Mar 20
🫘 Green Beans (Bush) Mar 13 – Mar 20
🌽 Sweet Corn Mar 13 – Mar 20
🌿 Basil Jan 23 – Feb 6 Mar 13 – Mar 20 Mar 20 – Mar 27
🧄 Garlic Fall: Oct 27 – Nov 24

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Mitchell Caverns's dates automatically after a lookup.

Reading the season in Mitchell Caverns

With roughly 277 frost-free days, Mitchell Caverns gardens fit long-season crops — melons, winter squash, sweet potatoes — with room left for spring and fall rounds of greens and roots. The first frost around Dec 8 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Mitchell Caverns, CA?

The average last spring frost in Mitchell Caverns is around Mar 6, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Mitchell Caverns, CA?

The average first fall frost in Mitchell Caverns arrives around Dec 8. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Mitchell Caverns?

About 277 frost-free days on average, from Mar 6 to Dec 8. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Mitchell Caverns in?

USDA zone 9a on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.