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When to Plant Chervil in Roseau County, MN

Roseau County, Minnesota Zone 3b May

Top priorities for Roseau County, Minnesota gardeners in May

Welcome to May in Zone 3b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 21
Avg. first frost September 22
Soil temp (4") 51°F
Watering Low
Pest pressure Low
Daylight 15 hrs
  1. Move chervil from tray to bed

    Frost risk is low now in Roseau County, Minnesota. If you've been covering beds overnight, you can stop.

  2. Direct-sow chervil

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

A few tasks this May that'll pay off in June
  • First harvests: chervil
  • Fall sowing: chervil

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Chervil is a delicate herb with a subtle anise-parsley flavor, essential in French cuisine as part of fines herbes. It prefers cool conditions and partial shade.

Roseau County, Minnesota is in USDA Zone 3b. The average last spring frost is May 21 and the first fall frost is September 22, giving you a growing season of approximately 124 days.

At an elevation of 655 feet, Roseau County receives approximately 32 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Chervil to ensure they mature before fall.

Roseau County, MN (Zone 3b) Short season
124 days
Last Spring Frost May 21
124 growing days
First Fall Frost September 22

Roseau County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (28 days to spare)
Start indoors: Mar 30 Transplant: May 4 🍅 Harvest: Jun 15 – Aug 17
Recommended (50%) ✓ Fits season (26 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Jun 25 – Aug 27
Safe Start (90%) ✓ Fits season (28 days to spare)
Start indoors: Apr 23 Transplant: May 28 🍅 Harvest: Jul 9 – Sep 10

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 Roseau County

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

Soil pH

Your soil pH (5.9–7.2) overlaps with Chervil's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — Chervil will thrive.

How to Plant Chervil

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Chervil

3
successive plantings in your 124-day season

Sow every 4.6 weeks. Last sowing by Jul 24 to harvest before frost.

For a dedicated fall crop, sow by Jun 30.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Chervil

Chervil needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Chervil Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 2.2" 3.9" 0" ✅ Rainfall sufficient
Jun 2.2" 4.3" 0" ✅ Rainfall sufficient
Jul 2.2" 3.8" 0" ✅ Rainfall sufficient
Aug 2.2" 3.7" 0" ✅ Rainfall sufficient
Sep 2.2" 2.4" 0" ✅ Rainfall sufficient
Oct 2.7" 0" ❄️ Dormant
Nov 1.9" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Roseau County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Chervil 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.

Chervil needs ~462 GDD — county provides 1,147 GDD Excellent fit

Chervil Planting Timeline — Roseau County, MN

Chervil Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 14 May 14 – May 28
Direct Sow May 14 May 14 – Jun 4
Harvest June 25 Jun 25 – Aug 27
Fall Sowing June 30 Jun 30 – Jul 14

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 3b

📆 Growing Season

124 days in Roseau County

Growing Tips for Chervil in Roseau County

Direct sow Chervil outdoors after May 21 in Roseau County when soil has warmed and frost danger has passed.

Common pests for Chervil 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 early spring or fall as chervil bolts in heat. Provide shade and cool conditions. Harvest outer leaves as needed; use fresh as it loses flavor when dried.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Chervil in Roseau County, MN?

Roseau County is in Zone 3b with an average last frost of May 21. Plan your Chervil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Roseau County, MN?

Roseau County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 21 and first fall frost is September 22.

🌱

Your Roseau County Garden Planner — Free

A 24-page printable planner built for Roseau County (Zone 3b). 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 Roseau County, MN. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.