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When to Plant Fennel (herb) in Middlesex County, NJ

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.

Middlesex County, New Jersey is in USDA Zone 7a. The average last spring frost is March 29 and the first fall frost is November 12, giving you a growing season of approximately 228 days.

At an elevation of 947 feet, Middlesex County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 94ยฐF, providing good warmth for Fennel (herb) during the growing season.

Middlesex County, NJ (Zone 7a) Long season
228 days
Last Spring Frost March 29
228 growing days
First Fall Frost November 12

Middlesex County Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (102 days to spare)
Start indoors: Feb 18 Transplant: Mar 18 🍅 Harvest: May 20 – Jul 29
Recommended (50%) ✓ Fits season (102 days to spare)
Start indoors: Feb 22 Transplant: Mar 22 🍅 Harvest: May 24 – Aug 2
Safe Start (90%) ✓ Fits season (111 days to spare)
Start indoors: Mar 5 Transplant: Apr 2 🍅 Harvest: Jun 4 – Aug 13

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 Middlesex County

How your county's soil matches Fennel (herb)'s growing requirements.

Soil pH

Your soil pH (5.0โ€“6.6) overlaps with Fennel (herb)'s range (5.5โ€“7.0), though not a perfect match.

Soil Texture

The silt loam soil in Middlesex County is excellent for Fennel (herb) โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Fennel (herb).

How to Plant Fennel (herb)

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Fennel (herb)

4
successive plantings in your 228-day season

Sow every 6.9 weeks. Last sowing by Aug 14 to harvest before frost.

For a dedicated fall crop, sow by Sep 03.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 328 gal / 100 sq ft

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 โ€” 3.3" 0" โ„๏ธ Dormant
Feb โ€” 3.1" 0" โ„๏ธ Dormant
Mar 4.3" 3.6" 0.7" ๐Ÿ’ง Light watering
Apr 4.3" 4.2" 0.1" ๐Ÿ’ง Light watering
May 4.3" 4.8" 0" โœ… Rainfall sufficient
Jun 4.3" 4.9" 0" โœ… Rainfall sufficient
Jul 4.3" 4" 0.3" ๐Ÿ’ง Light watering
Aug 4.3" 4.3" 0" โœ… Rainfall sufficient
Sep 4.3" 3.4" 0.9" ๐Ÿ’ง Light watering
Oct 4.3" 3.7" 0.6" ๐Ÿ’ง Light watering
Nov 4.3" 3.2" 1.1" ๐Ÿ’ง Light watering
Dec โ€” 3" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Marโ€“Nov in Middlesex County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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) needs ~1,538 GDD — county provides 4,674 GDD Excellent fit

Fennel (herb) Planting Timeline โ€” Middlesex County, NJ

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 โ€“ Mar 8
Transplant Outdoors March 22 Mar 22 โ€“ Apr 5
Direct Sow March 15 Mar 15 โ€“ Apr 5
Harvest May 24 May 24 โ€“ Aug 2
Fall Sowing September 3 Sep 3 โ€“ Sep 17

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

Month-by-Month Timeline

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

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท Only during dry spells

๐Ÿ“… Days to Maturity

60โ€“90 days

๐Ÿงช Soil pH

Needs 5.5โ€“7 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 7a

๐Ÿ“† Growing Season

228 days in Middlesex County

Growing Tips for Fennel (herb) in Middlesex County

Direct sow Fennel (herb) outdoors after March 29 in Middlesex 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

  • Tomatoes
  • Peppers
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Fennel (herb) in Middlesex County, NJ?

Middlesex County is in Zone 7a with an average last frost of March 29. Plan your Fennel (herb) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Middlesex County, NJ?

Middlesex County, New Jersey is in USDA Hardiness Zone 7a. The average last spring frost is March 29 and first fall frost is November 12.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Middlesex County gardeners in Zone 7a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Middlesex County, NJ. Local conditions may vary. Last updated: April 2026.