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When to Plant Tomatillo in Macoupin County, IL

Macoupin County, Illinois Zone 6b May

Macoupin County, Illinois gardeners: here's your May plan

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

Avg. last frost April 11
Avg. first frost October 21
Soil temp (4") 64°F
Watering Low
Pest pressure Low
Daylight 14.2 hrs
Get ahead of June
  • Starting indoors: tomatillo
  • First harvests: tomatillo

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Tomatillos are a Mexican staple that produces tart, green fruits enclosed in papery husks. They are essential for salsa verde and green sauces.

Macoupin County, Illinois is in USDA Zone 6b. The average last spring frost is April 11 and the first fall frost is October 21, giving you a growing season of approximately 193 days.

At an elevation of 859 feet, Macoupin County receives approximately 30.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Tomatillo during the growing season.

Macoupin County, IL (Zone 6b) Moderate season
193 days
Last Spring Frost April 11
193 growing days
First Fall Frost October 21
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Macoupin County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Start indoors: Feb 7 Transplant: Apr 18 🍅 Harvest: Jun 20 – Aug 29
Recommended (50%) ✓ Fits season (46 days to spare)
Start indoors: Feb 14 Transplant: Apr 25 🍅 Harvest: Jun 27 – Sep 5
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Feb 23 Transplant: May 4 🍅 Harvest: Jul 6 – Sep 14

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 Macoupin County

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

Soil pH

Your soil pH (6.0–7.2) overlaps with Tomatillo's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Macoupin County is excellent for Tomatillo — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.0%) — Tomatillo will thrive.

How to Plant Tomatillo

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

Succession Planting Tomatillo

3
successive plantings in your 193-day season

Sow every 6.9 weeks. Last sowing by Jul 28 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 734 gal / 100 sq ft

Monthly Watering Guide for Tomatillo

Tomatillo needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Tomatillo Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.8" 2.7" 2.1" 💧 Light watering
May 4.8" 3.8" 1" 💧 Light watering
Jun 4.8" 4.3" 0.5" 💧 Light watering
Jul 4.8" 3" 1.8" 💧 Light watering
Aug 4.8" 3.6" 1.2" 💧 Light watering
Sep 4.8" 2.7" 2.1" 💧 Light watering
Oct 4.8" 2.1" 2.7" 🚿 Regular watering
Nov 2" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

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

Tomatillo 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.

Tomatillo needs ~1,269 GDD — county provides 3,377 GDD Excellent fit

Tomatillo Planting Timeline — Macoupin County, IL

Tomatillo Planting Calendar

Activity When Date Range
Start Indoors February 14 Feb 14 – Feb 28
Transplant Outdoors April 25 Apr 25 – May 9
Direct Sow April 18 Apr 18 – May 9
Harvest June 27 Jun 27 – Sep 5

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · 1-2 times/week

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

193 days in Macoupin County

Growing Tips for Tomatillo in Macoupin County

Direct sow Tomatillo outdoors after April 11 in Macoupin County when soil has warmed and frost danger has passed.

Common pests for Tomatillo 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. Plant at least two plants for cross-pollination. Harvest when fruits fill the husk and it begins to split.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel
  • Dill

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Tomatillo in Macoupin County, IL?

Macoupin County is in Zone 6b with an average last frost of April 11. Plan your Tomatillo planting based on this frost date — see the calendar above for exact timing.

What planting zone is Macoupin County, IL?

Macoupin County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 11 and first fall frost is October 21.

🌱

Your Macoupin County Garden Planner — Free

A 24-page printable planner built for Macoupin 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 Macoupin 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.