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When to Plant Ground Cherry in St. Clair County, IL

St. Clair County, Illinois Zone 7a May

Your May game plan for St. Clair County, Illinois

Welcome to May in Zone 7a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 2
Avg. first frost November 2
Soil temp (4") 63°F
Watering Low
Pest pressure Low
Daylight 14.1 hrs

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Ground cherries produce small, sweet, tropical-tasting berries enclosed in papery husks. They are related to tomatillos and cape gooseberries and self-sow readily.

St. Clair County, Illinois is in USDA Zone 7a. The average last spring frost is April 2 and the first fall frost is November 2, giving you a growing season of approximately 214 days.

At an elevation of 711 feet, St. Clair County receives approximately 34.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Ground Cherry during the growing season.

St. Clair County, IL (Zone 7a) Long season
214 days
Last Spring Frost April 2
214 growing days
First Fall Frost November 2

St. Clair County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (69 days to spare)
Transplant: Apr 16 🍅 Harvest: Jun 25 – Aug 20
Recommended (50%) ✓ Fits season (67 days to spare)
Transplant: Apr 23 🍅 Harvest: Jul 2 – Aug 27
Safe Start (90%) ✓ Fits season (73 days to spare)
Transplant: May 8 🍅 Harvest: Jul 17 – Sep 11

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 Ground Cherry's growing requirements.

Soil pH

Your soil pH (6.0–7.3) is within Ground Cherry's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — Ground Cherry will thrive.

How to Plant Ground Cherry

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Succession Planting Ground Cherry

3
successive plantings in your 214-day season

Sow every 7.4 weeks. Last sowing by Aug 14 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 756 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Ground Cherry

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

Month Ground Cherry Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 4" 0.3" 💧 Light watering
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3.9" 0.4" 💧 Light watering
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 2.5" 1.8" 💧 Light watering
Nov 4.3" 2.4" 1.9" 💧 Light watering
Dec 1.8" 0" ❄️ Dormant

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

Ground Cherry 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.

Ground Cherry needs ~1,214 GDD — county provides 3,584 GDD Excellent fit

Ground Cherry Planting Timeline — St. Clair County, IL

Ground Cherry Planting Calendar

Activity When Date Range
Transplant Outdoors April 23 Apr 23 – May 7
Harvest July 2 Jul 2 – Aug 27

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Transplant Outdoors
May Transplant Outdoors
June
July Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

65–80 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 7a

📆 Growing Season

214 days in St. Clair County

Growing Tips for Ground Cherry in St. Clair County

Direct sow Ground Cherry outdoors after April 02 in St. Clair County when soil has warmed and frost danger has passed.

Common pests for Ground Cherry in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Let fruits fall to the ground naturally when ripe inside their husks. The husk turns brown and papery when the fruit is ready.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Ground Cherry in St. Clair County, IL?

St. Clair County is in Zone 7a with an average last frost of April 2. Plan your Ground Cherry planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Clair County, IL?

St. Clair County, Illinois is in USDA Hardiness Zone 7a. The average last spring frost is April 2 and first fall frost is November 2.

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Your St. Clair County Garden Planner — Free

A 24-page printable planner built for St. Clair County (Zone 7a). 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, IL. 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.