When to Plant Fennel in Vilas County, WI
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.
Vilas County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 21 and the first fall frost is September 29, giving you a growing season of approximately 131 days.
At an elevation of 543 feet, Vilas County receives approximately 36.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Fennel to ensure they mature before fall.
Vilas County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.3
Drainage
Well Drained
Plant Planting Risk Windows
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.
Soil Compatibility in Vilas County
How your county's soil matches Fennel's growing requirements.
Soil pH
Your soil pH (5.8–7.3) overlaps with Fennel's range (5.5–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Vilas County is excellent for Fennel — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.0%) — Fennel will thrive.
How to Plant Fennel
Succession Planting Fennel
Sow every 6.9 weeks. Last sowing by Jul 01 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Fennel
Fennel needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.
| Month | Fennel Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 2.6" | 0" | ❄️ Dormant |
| Apr | — | 3.6" | 0" | ❄️ Dormant |
| May | 2.6" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jun | 2.6" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jul | 2.6" | 4.2" | 0" | ✅ Rainfall sufficient |
| Aug | 2.6" | 4.4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.6" | 2.9" | 0" | ✅ Rainfall sufficient |
| Oct | — | 2.9" | 0" | ❄️ Dormant |
| Nov | — | 2.2" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Vilas County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Fennel Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Fennel Planting Timeline — Vilas County, WI
Fennel Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 19 | Mar 19 – Apr 2 |
| Transplant Outdoors | June 11 | Jun 11 – Jun 25 |
| Direct Sow | June 4 | Jun 4 – Jun 25 |
| Harvest | August 13 | Aug 13 – Sep 24 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.6"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 4a
📆 Growing Season
131 days in Vilas County
Growing Tips for Fennel in Vilas County
Direct sow Fennel outdoors after May 21 in Vilas County when soil has warmed and frost danger has passed.
Common pests for Fennel in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
Fennel in Other Locations
Frequently Asked Questions
When should I plant Fennel in Vilas County, WI?
Vilas County is in Zone 4a with an average last frost of May 21. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.
What planting zone is Vilas County, WI?
Vilas County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 21 and first fall frost is September 29.
Plan Your Garden with Confidence
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