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When to Plant Fennel in Jackson County, OR

Florence fennel is grown for its swollen bulb-like stem base, which has a mild anise flavor. It is crisp raw in salads and sweet when roasted or braised.

Jackson County, Oregon is in USDA Zone 8a. The average last spring frost is May 7 and the first fall frost is October 10, giving you a growing season of approximately 156 days.

At an elevation of 422 feet, Jackson County receives approximately 46 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Fennel during the growing season.

Jackson County, OR (Zone 8a) Moderate season
156 days
Last Spring Frost May 7
156 growing days
First Fall Frost October 10

Jackson County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (40 days to spare)
Start indoors: Mar 8 Transplant: May 10 🍅 Harvest: Jul 12 – Aug 23
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Mar 19 Transplant: May 21 🍅 Harvest: Jul 23 – Sep 3
Safe Start (90%) ✓ Fits season (41 days to spare)
Start indoors: Apr 14 Transplant: Jun 16 🍅 Harvest: Aug 18 – Sep 29

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
1.2″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 85 gal / 100 sq ft
Fennel needs ~1,200 GDD — county provides 2,496 GDD Excellent fit

Fennel Planting Timeline โ€” Jackson County, OR

Fennel Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 โ€“ Apr 2
Transplant Outdoors May 21 May 21 โ€“ Jun 4
Direct Sow May 14 May 14 โ€“ Jun 4
Harvest July 23 Jul 23 โ€“ Sep 3

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 8a

Growing Season

156 days

Growing Tips for Jackson County

Direct sow in late summer for fall harvest to reduce bolting. Hill soil around bulbs as they enlarge. Harvest when bulbs are tennis-ball sized before they elongate.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Peppers
  • Beans

Level Up Your Garden

Frequently Asked Questions

When should I plant Fennel in Jackson County, OR?

Jackson County is in Zone 8a with an average last frost of May 7. Plan your Fennel planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Jackson County, OR?

Jackson County, Oregon is in USDA Hardiness Zone 8a. The average last spring frost is May 7 and first fall frost is October 10.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Jackson 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 Jackson County, OR. Local conditions may vary. Last updated: April 2026.