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When to Plant Parsley in Flathead County, MT

Flathead County, Montana Zone 5a May

Flathead County, Montana gardeners: here's your May plan

Each item below is timed to Flathead County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost June 3
Avg. first frost September 10
Soil temp (4") 41°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Move parsley from tray to bed

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

  2. Outdoor sowing time: parsley

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

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Parsley is a biennial herb available in flat-leaf (Italian) and curly varieties. It is a nutritional powerhouse rich in vitamins C and K and adds fresh flavor to countless dishes.

Flathead County, Montana is in USDA Zone 5a. The average last spring frost is June 3 and the first fall frost is September 10, giving you a growing season of approximately 99 days.

At an elevation of 6,233 feet, Flathead County receives approximately 20.7 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Parsley during the growing season.

Flathead County, MT (Zone 5a) Very short season
99 days
Last Spring Frost June 3
99 growing days
First Fall Frost September 10

Flathead County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 17 Transplant: May 15 🍅 Harvest: Jul 17 – Sep 18
Recommended (50%) ✗ May not fit
Start indoors: Apr 29 Transplant: May 27 🍅 Harvest: Jul 29 – Sep 30
Safe Start (90%) ✗ May not fit
Start indoors: May 18 Transplant: Jun 15 🍅 Harvest: Aug 17 – Oct 19

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 Flathead County

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

Soil pH

Your soil pH (6.6–8.4) is more alkaline than Parsley prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Flathead County is excellent for Parsley — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Parsley

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

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

Plant Water Budget

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

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Parsley

Parsley 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 Parsley Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.6" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 2.7" 0" ❄️ Dormant
Jun 2.6" 1.5" 1.1" 💧 Light watering
Jul 2.6" 1.5" 1.1" 💧 Light watering
Aug 2.6" 2.1" 0.5" 💧 Light watering
Sep 2.6" 1.5" 1.1" 💧 Light watering
Oct 1.9" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

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

Parsley 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.

Parsley needs ~1,068 GDD — county provides 1,509 GDD Excellent fit

Parsley Planting Timeline — Flathead County, MT

Parsley Planting Calendar

Activity When Date Range
Start Indoors April 29 Apr 29 – May 13
Transplant Outdoors May 27 May 27 – Jun 10
Direct Sow May 20 May 20 – Jun 10
Harvest July 29 Jul 29 – Sep 30
Fall Sowing July 2 Jul 2 – Jul 16

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

99 days in Flathead County

Growing Tips for Parsley in Flathead County

Direct sow Parsley outdoors after June 03 in Flathead County when soil has warmed and frost danger has passed.

Common pests for Parsley in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Soak seeds overnight as germination is slow. Harvest outer stems first to keep plants productive. Parsley attracts swallowtail butterflies.

Companion Planting

Good Companions

Avoid Planting Near

  • Mint
  • Lettuce

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Parsley in Flathead County, MT?

Flathead County is in Zone 5a with an average last frost of June 3. Plan your Parsley planting based on this frost date — see the calendar above for exact timing.

What planting zone is Flathead County, MT?

Flathead County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 3 and first fall frost is September 10.

🌱

Your Flathead County Garden Planner — Free

A 24-page printable planner built for Flathead County (Zone 5a). 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 Flathead County, MT. 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.