When to Plant Fennel (herb) in Clark County, WI
Your May planting checklist for Clark County, Wisconsin
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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Get fennel (herb) in the ground
Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.
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Plant fennel (herb) from seed, right in the garden
Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.
June will be here before you know it — start on
- Starting indoors: fennel (herb)
Herb fennel is grown for its aromatic leaves, stalks, and seeds rather than a bulb. It has a strong anise flavor and its flowers attract beneficial insects.
Clark County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 13 and the first fall frost is September 30, giving you a growing season of approximately 140 days.
At an elevation of 850 feet, Clark County receives approximately 39.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Fennel (herb) to ensure they mature before fall.
Clark County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-6.8
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 Clark County
How your county's soil matches Fennel (herb)'s growing requirements.
Soil pH
Your soil pH (6.1–6.8) is within Fennel (herb)'s preferred range (5.5–7.0).
Soil Texture
The silt loam soil in Clark County is excellent for Fennel (herb) — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.9%). Annual compost additions will help Fennel (herb).
How to Plant Fennel (herb)
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Fennel (herb)
Sow every 6.9 weeks. Last sowing by Jul 02 to harvest before frost.
For a dedicated fall crop, sow by Jul 08.
Plant Water Budget
Monthly Watering Guide for Fennel (herb)
Fennel (herb) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Fennel (herb) Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 2" | 0" | ❄️ Dormant |
| Mar | — | 2.6" | 0" | ❄️ Dormant |
| Apr | — | 3.9" | 0" | ❄️ Dormant |
| May | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Aug | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Sep | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Oct | — | 2.8" | 0" | ❄️ Dormant |
| Nov | — | 3" | 0" | ❄️ Dormant |
| Dec | — | 2.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Clark County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Fennel (herb) 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 (herb) Planting Timeline — Clark County, WI
Fennel (herb) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 1 | Apr 1 – Apr 15 |
| Transplant Outdoors | May 6 | May 6 – May 20 |
| Direct Sow | May 6 | May 6 – May 27 |
| Harvest | July 8 | Jul 8 – Sep 16 |
| Fall Sowing | July 8 | Jul 8 – Jul 22 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 5.5–7 · Your soil: ideal
🗺️ USDA Zone
Zone 4b
📆 Growing Season
140 days in Clark County
Growing Tips for Fennel (herb) in Clark County
Direct sow Fennel (herb) outdoors after May 13 in Clark County when soil has warmed and frost danger has passed.
Common pests for Fennel (herb) 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 spring or fall. Unlike Florence fennel, herb fennel does not form a bulb. Harvest fronds as needed and seeds when they turn brown. Self-sows readily.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Fennel (herb) in Other Locations
Frequently Asked Questions
When should I plant Fennel (herb) in Clark County, WI?
Clark County is in Zone 4b with an average last frost of May 13. Plan your Fennel (herb) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clark County, WI?
Clark County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 13 and first fall frost is September 30.
Your Clark County Garden Planner — Free
A 24-page printable planner built for Clark County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.