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When to plant Tomatillo in Mitchell County, IA

Plant Tomatillo in Mitchell County after May 3; the prime window is May 10–May 31.

When to Plant Tomatillo in Mitchell County, IA

Mitchell County, Iowa Zone 5a June

June in Mitchell County, Iowa — your action list

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Mitchell County, Iowa.

Avg. last frost May 3
Avg. first frost October 7
Soil temp (4") 67°F
Watering Low
Pest pressure High
Daylight 15.2 hrs
  1. Time to start tomatillo inside

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

July prep starts now
  • 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.

Mitchell County, Iowa is in USDA Zone 5a. The average last spring frost is May 3 and the first fall frost is October 7, giving you a growing season of approximately 157 days.

At an elevation of 506 feet, Mitchell County receives approximately 36.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Tomatillo to ensure they mature before fall.

Mitchell County, IA (Zone 5a) Moderate season
157 days
Last Spring Frost May 3
157 growing days
First Fall Frost October 7

Mitchell County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.3

Drainage

Well Drained

Tomatillo Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Mar 2 Transplant: May 11 🍅 Harvest: Jul 13 – Sep 21
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: Mar 8 Transplant: May 17 🍅 Harvest: Jul 19 – Sep 27
Safe Start (90%) ✓ Fits season (7 days to spare)
Start indoors: Mar 20 Transplant: May 29 🍅 Harvest: Jul 31 – Oct 9

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 Mitchell County

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

Soil pH

Your soil pH (5.9–7.3) overlaps with Tomatillo's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Tomatillo

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

Succession Planting Tomatillo

3
successive plantings in your 157-day season

Sow every 6.9 weeks. Last sowing by Jul 14 to harvest before frost.

Tomatillo Water Budget

Plant needs
1.1″/week
Rainfall provides
1.0″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 188 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 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 4.8" 4" 0.8" 💧 Light watering
Jun 4.8" 5.1" 0" ✅ Rainfall sufficient
Jul 4.8" 3.9" 0.9" 💧 Light watering
Aug 4.8" 3.9" 0.9" 💧 Light watering
Sep 4.8" 2.9" 1.9" 💧 Light watering
Oct 4.8" 2.4" 2.4" 🚿 Regular watering
Nov 2.8" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Mitchell 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 ~942 GDD — county provides 2,041 GDD Excellent fit

Tomatillo Planting Timeline — Mitchell County, IA

Tomatillo Planting Calendar

Activity When Date Range
Start Indoors March 8 Mar 8 – Mar 22
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 10 May 10 – May 31
Harvest July 19 Jul 19 – Sep 27

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · Only during dry spells

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

157 days in Mitchell County

Growing Tips for Tomatillo in Mitchell County

Direct sow Tomatillo outdoors after May 03 in Mitchell 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 Mitchell County, IA?

Mitchell County is in Zone 5a with an average last frost of May 3. Plan your Tomatillo planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mitchell County, IA?

Mitchell County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is May 3 and first fall frost is October 7.

When should I plant Tomatillo in Mitchell County, IA?

In Mitchell County, IA, plant Tomatillo after the last frost (around May 3) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Mitchell County, IA for Tomatillo?

Mitchell County sits in USDA Zone 5a. Tomatillo grows reliably in zones 4a through 11b, so it's a good fit here.

Can Tomatillo grow in Mitchell County's climate?

Yes — Tomatillo grows well in Mitchell County's temperate climate. Mitchell County averages a 157-day frost-free season, with last frost around May 3 and first frost around October 7.

🌱

Your Mitchell County Garden Planner — Free

A 22-page printable planner built for Mitchell County (Zone 5a). 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 Mitchell County, IA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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