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When to Plant Delicata Squash in St. Clair County, MO

St. Clair County, Missouri Zone 6b May

Your May gardening checklist

May is a pivotal month for St. Clair County, Missouri gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 8
Avg. first frost October 26
Soil temp (4") 65°F
Watering Low
Pest pressure Low
Daylight 14.1 hrs
  1. Start delicata squash under lights

    Your window is short. These crops want several weeks of indoor growth before they go outside.

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Delicata squash is a winter squash with an edible skin and sweet, creamy orange flesh. Its compact vines make it suitable for smaller gardens.

St. Clair County, Missouri is in USDA Zone 6b. 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 90°F, providing good warmth for Delicata Squash during the growing season.

St. Clair County, MO (Zone 6b) Long season
201 days
Last Spring Frost April 8
201 growing days
First Fall Frost October 26
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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 (68 days to spare)
Start indoors: Feb 25 Transplant: Apr 15 🍅 Harvest: Jul 8 – Aug 12
Recommended (50%) ✓ Fits season (68 days to spare)
Start indoors: Mar 4 Transplant: Apr 22 🍅 Harvest: Jul 15 – Aug 19
Safe Start (90%) ✓ Fits season (68 days to spare)
Start indoors: Mar 15 Transplant: May 3 🍅 Harvest: Jul 26 – Aug 30

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 St. Clair County

How your county's soil matches Delicata Squash's growing requirements.

Soil pH

Your soil pH (5.5–6.7) overlaps with Delicata Squash's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in St. Clair County is excellent for Delicata Squash — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Delicata Squash.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Delicata Squash.

How to Plant Delicata Squash

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Delicata Squash

2
successive plantings in your 201-day season

Sow every 9.1 weeks. Last sowing by Jul 18 to harvest before frost.

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

Monthly Watering Guide for Delicata Squash

Delicata Squash needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Delicata Squash Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 4.3" 0" ✅ Rainfall sufficient
May 4.3" 5.2" 0" ✅ Rainfall sufficient
Jun 4.3" 4.8" 0" ✅ Rainfall sufficient
Jul 4.3" 4.8" 0" ✅ Rainfall sufficient
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 3.9" 0.4" 💧 Light watering
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

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

Delicata Squash 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.

Delicata Squash needs ~1,575 GDD — county provides 3,517 GDD Excellent fit

Delicata Squash Planting Timeline — St. Clair County, MO

Delicata Squash Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 – Mar 18
Transplant Outdoors April 22 Apr 22 – May 6
Direct Sow April 15 Apr 15 – May 6
Harvest July 15 Jul 15 – Aug 19

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

80–100 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

201 days in St. Clair County

Growing Tips for Delicata Squash in St. Clair County

Direct sow Delicata Squash outdoors after April 08 in St. Clair County when soil has warmed and frost danger has passed.

Common pests for Delicata Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after last frost on mounds. Harvest when skin is hard and ivory with green stripes. The thin skin does not need peeling. Stores 2-3 months in a cool place.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

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

St. Clair County is in Zone 6b with an average last frost of April 8. Plan your Delicata Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Clair County, MO?

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

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Your St. Clair County Garden Planner — Free

A 24-page printable planner built for St. Clair County (Zone 6b). 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 St. Clair County, MO. 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.