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When to Plant Parsley in St. Clair County, MO

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.

St. Clair County, Missouri is in USDA Zone 6a. The average last spring frost is April 8 and the first fall frost is October 26, giving you a growing season of approximately 201 days.

At an elevation of 699 feet, St. Clair County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Parsley during the growing season.

St. Clair County, MO (Zone 6a) Long season
201 days
Last Spring Frost April 8
201 growing days
First Fall Frost October 26

St. Clair County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (82 days to spare)
Start indoors: Feb 25 Transplant: Mar 25 🍅 Harvest: May 27 – Jul 29
Recommended (50%) ✓ Fits season (82 days to spare)
Start indoors: Mar 4 Transplant: Apr 1 🍅 Harvest: Jun 3 – Aug 5
Safe Start (90%) ✓ Fits season (82 days to spare)
Start indoors: Mar 15 Transplant: Apr 12 🍅 Harvest: Jun 14 – Aug 16

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Parsley needs ~1,225 GDD — county provides 3,517 GDD Excellent fit

Parsley Planting Timeline โ€” St. Clair County, MO

Parsley Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 โ€“ Mar 18
Transplant Outdoors April 1 Apr 1 โ€“ Apr 15
Direct Sow March 25 Mar 25 โ€“ Apr 15
Fall Sowing August 17 Aug 17 โ€“ Aug 31
Harvest June 3 Jun 3 โ€“ Aug 5

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“80 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6a

Growing Season

201 days

Growing Tips for St. Clair County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Parsley in St. Clair County, MO?

St. Clair County is in Zone 6a with an average last frost of April 8. Plan your Parsley planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is St. Clair County, MO?

St. Clair County, Missouri is in USDA Hardiness Zone 6a. The average last spring frost is April 8 and first fall frost is October 26.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help St. Clair County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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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 St. Clair County, MO. Local conditions may vary. Last updated: April 2026.