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When to Plant Parsley in Powder River County, MT

Powder River County, Montana Zone 4b May

What to do in May

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Powder River County, Montana.

Avg. last frost May 15
Avg. first frost September 22
Soil temp (4") 38°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
  1. Harden off and plant parsley

    Your last frost (May 15) has passed. These warm-season crops can handle outdoor soil now.

  2. Seed parsley outdoors

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Get ahead of June
  • Starting indoors: parsley
  • Fall sowing: parsley

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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.

Powder River County, Montana is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 22, giving you a growing season of approximately 130 days.

At an elevation of 6,328 feet, Powder River County receives approximately 19.4 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Parsley to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Parsley successfully. Mulch heavily to conserve soil moisture.

Powder River County, MT (Zone 4b) Short season
130 days
Last Spring Frost May 15
130 growing days
First Fall Frost September 22

Powder River County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Mar 30 Transplant: May 4 🍅 Harvest: Jul 6 – Sep 7
Recommended (50%) ✓ Fits season (11 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jul 10 – Sep 11
Safe Start (90%) ✓ Fits season (11 days to spare)
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Jul 24 – Sep 25

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 Powder River County

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

Soil pH

Your soil pH (6.5–7.9) is more alkaline than Parsley prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Parsley.

How to Plant Parsley

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 Parsley

2
successive plantings in your 130-day season

Sow every 6.9 weeks. Last sowing by Jul 04 to harvest before frost.

For a dedicated fall crop, sow by Jun 30.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.6″/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 1.4" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 2.6" 2.7" 0" ✅ Rainfall sufficient
Jun 2.6" 1.3" 1.3" 🚿 Regular watering
Jul 2.6" 1.6" 1" 💧 Light watering
Aug 2.6" 1.8" 0.8" 💧 Light watering
Sep 2.6" 1.6" 1" 💧 Light watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Powder River 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 ~858 GDD — county provides 1,592 GDD Excellent fit

Parsley Planting Timeline — Powder River County, MT

Parsley Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 8 May 8 – May 22
Direct Sow May 8 May 8 – May 29
Harvest July 10 Jul 10 – Sep 11
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 Fall Sowing
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 4b

📆 Growing Season

130 days in Powder River County

Growing Tips for Parsley in Powder River County

Direct sow Parsley outdoors after May 15 in Powder River 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 Powder River County, MT?

Powder River County is in Zone 4b with an average last frost of May 15. Plan your Parsley planting based on this frost date — see the calendar above for exact timing.

What planting zone is Powder River County, MT?

Powder River County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 22.

🌱

Your Powder River County Garden Planner — Free

A 24-page printable planner built for Powder River 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.

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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 Powder River 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.