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When to Plant Tomatillo in Cass County, ND

Cass County, North Dakota Zone 4a May

May in the garden — Cass County, North Dakota

Welcome to May in Zone 4a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 11
Avg. first frost October 2
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Scatter tomatillo into prepared beds

    These tolerate cool soil, so you're not gambling by sowing now.

Get ahead of June
  • Transplants going out: 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.

Cass County, North Dakota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is October 2, giving you a growing season of approximately 144 days.

At an elevation of 839 feet, Cass County receives approximately 33.1 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Tomatillo to ensure they mature before fall.

Cass County, ND (Zone 4a) Short season
144 days
Last Spring Frost May 11
144 growing days
First Fall Frost October 2

Cass County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 28 Transplant: May 23 🍅 Harvest: Jul 25 – Oct 3
Recommended (50%) ✗ May not fit
Start indoors: Mar 9 Transplant: Jun 1 🍅 Harvest: Aug 3 – Oct 12
Safe Start (90%) ✗ May not fit
Start indoors: Mar 20 Transplant: Jun 12 🍅 Harvest: Aug 14 – Oct 23

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 Cass County

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

Soil pH

Your soil pH (6.5–7.6) is more alkaline than Tomatillo prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Tomatillo.

How to Plant Tomatillo

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

Succession Planting Tomatillo

2
successive plantings in your 144-day season

Sow every 6.9 weeks. Last sowing by Jul 09 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
1.0″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 207 gal / 100 sq ft
Drought risk

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

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 0.8" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 4.8" 4.2" 0.6" 💧 Light watering
Jun 4.8" 5.8" 0" ✅ Rainfall sufficient
Jul 4.8" 3.9" 0.9" 💧 Light watering
Aug 4.8" 4.3" 0.5" 💧 Light watering
Sep 4.8" 2.8" 2" 💧 Light watering
Oct 4.8" 2.3" 2.5" 🚿 Regular watering
Nov 1.1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Cass 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 ~725 GDD — county provides 1,440 GDD Excellent fit

Tomatillo Planting Timeline — Cass County, ND

Tomatillo Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 25 May 25 – Jun 15
Harvest August 3 Aug 3 – Oct 12

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 4a

📆 Growing Season

144 days in Cass County

Growing Tips for Tomatillo in Cass County

Direct sow Tomatillo outdoors after May 11 in Cass 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 Cass County, ND?

Cass County is in Zone 4a with an average last frost of May 11. Plan your Tomatillo planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cass County, ND?

Cass County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is October 2.

🌱

Your Cass County Garden Planner — Free

A 24-page printable planner built for Cass County (Zone 4a). 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 Cass County, ND. 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.