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When to Plant Tomatillo in Campbell County, WY

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

Campbell County, Wyoming is in USDA Zone 4a. The average last spring frost is May 20 and the first fall frost is September 20, giving you a growing season of approximately 123 days.

At an elevation of 8,132 feet, Campbell County receives approximately 22.3 inches of rainfall annually with predominantly loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Tomatillo to ensure they mature before fall.

Campbell County, WY (Zone 4a) Short season
123 days
Last Spring Frost May 20
123 growing days
First Fall Frost September 20

Campbell County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 12 Transplant: Jun 4 🍅 Harvest: Aug 6 – Oct 15
Recommended (50%) ✗ May not fit
Start indoors: Mar 18 Transplant: Jun 10 🍅 Harvest: Aug 12 – Oct 21
Safe Start (90%) ✗ May not fit
Start indoors: Apr 5 Transplant: Jun 28 🍅 Harvest: Aug 30 – Nov 8

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 Campbell County

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

Soil pH

Your soil pH (6.7โ€“7.6) is more alkaline than Tomatillo prefers (6.0โ€“7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Campbell County is excellent for Tomatillo โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.1%). 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 123-day season

Sow every 6.9 weeks. Last sowing by Jun 27 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.8″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 445 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” 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 โ€” 1.7" 0" โ„๏ธ Dormant
Feb โ€” 1.2" 0" โ„๏ธ Dormant
Mar โ€” 1.9" 0" โ„๏ธ Dormant
Apr โ€” 2.4" 0" โ„๏ธ Dormant
May 4.8" 2.7" 2.1" ๐Ÿ’ง Light watering
Jun 4.8" 1.4" 3.4" ๐Ÿšฟ Regular watering
Jul 4.8" 2" 2.8" ๐Ÿšฟ Regular watering
Aug 4.8" 2.4" 2.4" ๐Ÿšฟ Regular watering
Sep 4.8" 1.6" 3.2" ๐Ÿšฟ Regular watering
Oct โ€” 2.2" 0" โ„๏ธ Dormant
Nov โ€” 1.5" 0" โ„๏ธ Dormant
Dec โ€” 1.4" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Mayโ€“Sep in Campbell County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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 ~888 GDD — county provides 1,506 GDD Excellent fit

Tomatillo Planting Timeline โ€” Campbell County, WY

Tomatillo Planting Calendar

Activity When Date Range
Start Indoors March 18 Mar 18 โ€“ Apr 1
Transplant Outdoors June 10 Jun 10 โ€“ Jun 24
Direct Sow June 3 Jun 3 โ€“ Jun 24
Harvest August 12 Aug 12 โ€“ Oct 21

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

Month-by-Month Timeline

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

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1.1"/week ยท 1-2 times/week

๐Ÿ“… Days to Maturity

60โ€“85 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: too_alkaline

๐Ÿ—บ๏ธ USDA Zone

Zone 4a

๐Ÿ“† Growing Season

123 days in Campbell County

Growing Tips for Tomatillo in Campbell County

Direct sow Tomatillo outdoors after May 20 in Campbell 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.

Campbell County receives only 22" of rain annually. Tomatillo needs consistent moisture โ€” install drip irrigation or water deeply 2-3 times per week.

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 Campbell County, WY?

Campbell County is in Zone 4a with an average last frost of May 20. Plan your Tomatillo planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Campbell County, WY?

Campbell County, Wyoming is in USDA Hardiness Zone 4a. The average last spring frost is May 20 and first fall frost is September 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Campbell County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Campbell County, WY. Local conditions may vary. Last updated: April 2026.