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When to plant Fennel in Olean, MO

Olean's climate puts the Fennel spring window between April 13 and May 4. time plantings around the expected last-frost window for best survival.

When to Plant Fennel in Olean, MO

Miller County, Missouri Zone 6b August

Your August game plan for Miller County, Missouri

August is a pivotal month for Miller County, Missouri gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 6
Avg. first frost October 27
Soil temp (4") 82°F
Watering Moderate
Pest pressure High
Daylight 13.5 hrs
  1. Basket week: fennel

    If you can't use it all right away, check the food-preservation section of your planner.

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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.

Olean, Missouri is in USDA Zone 6b. The average last spring frost is April 6 and the first fall frost is October 27, giving you a growing season of approximately 204 days.

At an elevation of 1,086 feet, Miller County receives approximately 30.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Fennel during the growing season.

Olean, MO (Zone 6b) Long season
204 days
Last Spring Frost April 6
204 growing days
First Fall Frost October 27

Olean Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.7

Drainage

Well Drained

Fennel Planting Risk Windows

Early Start (70% safe) ✓ Fits season (84 days to spare)
Start indoors: Feb 3 Transplant: Apr 14 🍅 Harvest: Jun 16 – Jul 28
Recommended (50%) ✓ Fits season (85 days to spare)
Start indoors: Feb 9 Transplant: Apr 20 🍅 Harvest: Jun 22 – Aug 3
Safe Start (90%) ✓ Fits season (85 days to spare)
Start indoors: Feb 24 Transplant: May 5 🍅 Harvest: Jul 7 – Aug 18

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 Olean

How your county's soil matches Fennel's growing requirements.

Soil pH

Your soil pH (5.7–6.7) is within Fennel's preferred range (5.5–7.0).

Soil Texture

The silt loam soil in Miller County is excellent for Fennel — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Fennel.

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Fennel.

How to Plant Fennel

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Succession Planting Fennel

4
successive plantings in your 204-day season

Sow every 6.9 weeks. Last sowing by Jul 29 to harvest before frost.

Fennel Water Budget

Plant needs
0.6″/week
Rainfall provides
0.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.6" 3.4" 0" ✅ Rainfall sufficient
May 2.6" 4.2" 0" ✅ Rainfall sufficient
Jun 2.6" 3.6" 0" ✅ Rainfall sufficient
Jul 2.6" 3.1" 0" ✅ Rainfall sufficient
Aug 2.6" 3.1" 0" ✅ Rainfall sufficient
Sep 2.6" 3.1" 0" ✅ Rainfall sufficient
Oct 2.6" 2.4" 0.2" 💧 Light watering
Nov 1.8" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Miller 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 needs ~1,256 GDD — county provides 3,417 GDD Excellent fit

Fennel Planting Timeline — Olean, MO

Fennel Planting Calendar

Activity When Date Range
Start Indoors February 9 Feb 9 – Feb 23
Transplant Outdoors April 20 Apr 20 – May 4
Direct Sow April 13 Apr 13 – May 4
Harvest June 22 Jun 22 – Aug 3

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Harvest
September
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: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

204 days in Miller County

Growing Tips for Fennel in Olean

Direct sow Fennel outdoors after April 06 in Miller 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

  • Tomatoes
  • Peppers
  • Beans

Check more plant combinations with our Companion Planting Checker →

When should I plant Fennel in Olean, MO?

In Olean, MO, plant Fennel after the last frost (around April 6) and before the first frost (around October 27). Best results when soil holds above 50°F.

What growing zone is Olean, MO for Fennel?

Olean sits in USDA Zone 6b. Fennel grows reliably in zones 4a through 10b, so it's a good fit here.

Can Fennel grow in Olean's climate?

Yes — Fennel grows well in Olean's temperate climate. Olean averages a 204-day frost-free season, with last frost around April 6 and first frost around October 27.

🌱

Your Miller County Garden Planner — Free

A 22-page printable planner built for Miller County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Miller County, MO. Local conditions may vary. Last updated: August 2026.