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When to Plant Parsley in Sweetwater County, WY

Sweetwater County, Wyoming Zone 4b April

Your April gardening checklist

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

Avg. last frost May 29
Avg. first frost September 20
Soil temp (4") 16°F
Watering High
Pest pressure Low
Daylight 13.1 hrs
Coming up in May — start thinking about
  • Transplants going out: parsley
  • Direct-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.

Sweetwater County, Wyoming is in USDA Zone 4b. The average last spring frost is May 29 and the first fall frost is September 20, giving you a growing season of approximately 114 days.

At an elevation of 7,922 feet, Sweetwater County receives approximately 12.9 inches of rainfall annually with predominantly loam soil. Summer highs average 84°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.

Sweetwater County, WY (Zone 4b) Short season
114 days
Last Spring Frost May 29
114 growing days
First Fall Frost September 20

Sweetwater County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jul 14 – Sep 15
Recommended (50%) ✗ May not fit
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Jul 24 – Sep 25
Safe Start (90%) ✗ May not fit
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Aug 11 – Oct 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 Sweetwater County

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

Soil pH

Your soil pH (6.2–7.7) overlaps with Parsley's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Parsley.

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 12 weeks before your first frost date for a fall harvest.

Succession Planting Parsley

2
successive plantings in your 114-day season

Sow every 6.9 weeks. Last sowing by Jul 02 to harvest before frost.

For a dedicated fall crop, sow by Jun 28.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.5″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 371 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 0.8" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 2.6" 1.5" 1.1" 💧 Light watering
Jun 2.6" 1" 1.6" 🚿 Regular watering
Jul 2.6" 1.1" 1.5" 🚿 Regular watering
Aug 2.6" 1.3" 1.3" 🚿 Regular watering
Sep 2.6" 1" 1.6" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Sweetwater 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 ~910 GDD — county provides 1,482 GDD Excellent fit

Parsley Planting Timeline — Sweetwater County, WY

Parsley Planting Calendar

Activity When Date Range
Start Indoors April 17 Apr 17 – May 1
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 22 May 22 – Jun 12
Harvest July 24 Jul 24 – Sep 25
Fall Sowing June 28 Jun 28 – Jul 12

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 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 · 1-2 times/week

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

114 days in Sweetwater County

Growing Tips for Parsley in Sweetwater County

Direct sow Parsley outdoors after May 29 in Sweetwater 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 Sweetwater County, WY?

Sweetwater County is in Zone 4b with an average last frost of May 29. Plan your Parsley planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sweetwater County, WY?

Sweetwater County, Wyoming is in USDA Hardiness Zone 4b. The average last spring frost is May 29 and first fall frost is September 20.

🌱

Your Sweetwater County Garden Planner — Free

A 24-page printable planner built for Sweetwater 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 Sweetwater County, WY. Local conditions may vary. Last updated: April 2026.

Sources & credits

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