Palomar Mtn Obsy, CA Frost Dates & Growing Season

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

Last spring frost
Apr 29
~50% chance of frost after
First fall frost
Nov 18
~50% chance of frost before
Growing season
203 days
frost-free stretch
USDA zone
≈ 9a
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Apr 2 Apr 29 May 29
First fall frost Dec 8 Nov 18 Oct 27
Hard freeze (28°F), median last Apr 5 · first Dec 6

Computed from NOAA 1991–2020 climate normals at the PALOMAR MTN OBSY 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 Palomar Mtn Obsy

Computed from Palomar Mtn Obsy'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 Mar 4 – Mar 18 May 6 – May 13
🫑 Peppers Feb 18 – Mar 4 May 13 – May 20
🥬 Lettuce Mar 18 – Apr 1 Apr 1 – Apr 15 Apr 1 – Apr 29
🫛 Peas Mar 18 – Apr 1
🥕 Carrots Apr 8 – Apr 29
🥦 Broccoli Mar 11 – Mar 25 Apr 8 – Apr 22
🥬 Kale Mar 18 – Apr 1 Apr 1 – Apr 15 Apr 1 – Apr 15
🥒 Cucumbers Apr 1 – Apr 8 May 6 – May 13 May 6 – May 13
🥒 Zucchini Apr 1 – Apr 8 May 6 – May 13 May 6 – May 13
🫘 Green Beans (Bush) May 6 – May 13
🌽 Sweet Corn May 6 – May 13
🌿 Basil Mar 18 – Apr 1 May 6 – May 13 May 13 – May 20
🧄 Garlic Fall: Oct 7 – Nov 4

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 Palomar Mtn Obsy's dates automatically after a lookup.

Reading the season in Palomar Mtn Obsy

With roughly 203 frost-free days, Palomar Mtn Obsy 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 Nov 18 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Palomar Mtn Obsy, CA?

The average last spring frost in Palomar Mtn Obsy is around Apr 29, 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 Palomar Mtn Obsy, CA?

The average first fall frost in Palomar Mtn Obsy arrives around Nov 18. 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 Palomar Mtn Obsy?

About 203 frost-free days on average, from Apr 29 to Nov 18. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Palomar Mtn Obsy 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.