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When to Plant Cumin in San Juan County, WA

Cumin is a warm-season annual herb whose seeds are one of the most widely used spices globally. It requires a long, hot growing season of 3-4 months.

San Juan County, Washington is in USDA Zone 8a. The average last spring frost is March 26 and the first fall frost is November 3, giving you a growing season of approximately 222 days.

At an elevation of 371 feet, San Juan County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Cumin to ensure they mature before fall.

San Juan County, WA (Zone 8a) Long season
222 days
Last Spring Frost March 26
222 growing days
First Fall Frost November 3

San Juan County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (63 days to spare)
Start indoors: Feb 12 Transplant: Mar 12 🍅 Harvest: Jun 25 – Aug 27
Recommended (50%) ✓ Fits season (61 days to spare)
Start indoors: Feb 19 Transplant: Mar 19 🍅 Harvest: Jul 2 – Sep 3
Safe Start (90%) ✓ Fits season (59 days to spare)
Start indoors: Mar 21 Transplant: Apr 18 🍅 Harvest: Aug 1 – Oct 3

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Cumin needs ~1,265 GDD — county provides 2,553 GDD Excellent fit

Cumin Planting Timeline โ€” San Juan County, WA

Cumin Planting Calendar

Activity When Date Range
Start Indoors February 19 Feb 19 โ€“ Mar 5
Transplant Outdoors March 19 Mar 19 โ€“ Apr 2
Direct Sow March 12 Mar 12 โ€“ Apr 2
Fall Sowing August 25 Aug 25 โ€“ Sep 8
Harvest July 2 Jul 2 โ€“ Sep 3

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors Transplant Outdoors Direct Sow
April Transplant Outdoors Direct Sow
May โ€”
June โ€”
July Harvest
August Fall Sowing Harvest
September Fall Sowing Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

100โ€“120 days

Soil pH

6 โ€“ 8

USDA Zone

Zone 8a

Growing Season

222 days

Growing Tips for San Juan County

Start seeds indoors 4 weeks before last frost. Transplant after all danger of frost. Harvest when seed heads turn brown. Requires consistent warmth for proper seed development.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Level Up Your Garden

Frequently Asked Questions

When should I plant Cumin in San Juan County, WA?

San Juan County is in Zone 8a with an average last frost of March 26. Plan your Cumin planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is San Juan County, WA?

San Juan County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is March 26 and first fall frost is November 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help San Juan County gardeners in Zone 8a organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for San Juan County, WA. Local conditions may vary. Last updated: April 2026.