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When to Plant Garlic in Jefferson County, OR

Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.

Jefferson County, Oregon is in USDA Zone 6a. The average last spring frost is June 9 and the first fall frost is September 19, giving you a growing season of approximately 102 days.

At an elevation of 21 feet, Jefferson County receives approximately 36.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79ยฐF, so choose short-season varieties of Garlic to ensure they mature before fall.

Jefferson County, OR (Zone 6a) Short season
102 days
Last Spring Frost June 9
102 growing days
First Fall Frost September 19

Jefferson County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 30 🍅 Harvest: Aug 29 – Dec 12
Recommended (50%) ✗ May not fit
Transplant: Jun 9 🍅 Harvest: Sep 8 – Dec 22
Safe Start (90%) ✓ Fits season (275 days to spare)
Transplant: Jun 22 🍅 Harvest: Sep 21 – Jan 4

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
1.0″/week
Rainfall provides
1.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Garlic needs ~1,526 GDD — county provides 943 GDD May not mature

Garlic Planting Timeline โ€” Jefferson County, OR

Garlic Planting Calendar

Activity When Date Range
Fall Sowing August 8 Aug 8 โ€“ Aug 22

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May โ€”
June โ€”
July โ€”
August Fall Sowing
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“240 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 6a

Growing Season

102 days

Growing Tips for Jefferson County

Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Level Up Your Garden

Frequently Asked Questions

When should I plant Garlic in Jefferson County, OR?

Jefferson County is in Zone 6a with an average last frost of June 9. Plan your Garlic planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Jefferson County, OR?

Jefferson County, Oregon is in USDA Hardiness Zone 6a. The average last spring frost is June 9 and first fall frost is September 19.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Jefferson County gardeners in Zone 6a 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 Jefferson County, OR. Local conditions may vary. Last updated: April 2026.