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When to plant Tomatillo in Boundary County, ID

Plant Tomatillo in Boundary County during the brief May 17–June 7 window. With 135 frost-free days, fall plantings can't mature before September 22.

When to Plant Tomatillo in Boundary County, ID

Boundary County, Idaho Zone 6a August

Boundary County, Idaho gardeners: here's your August plan

August rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Boundary County, Idaho.

Avg. last frost May 10
Avg. first frost September 22
Soil temp (4") 61°F
Watering High
Pest pressure High
Daylight 14.2 hrs
  1. Start harvesting tomatillo

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

Before September arrives, get these ready
  • 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.

Boundary County, Idaho is in USDA Zone 6a. The average last spring frost is May 10 and the first fall frost is September 22, giving you a growing season of approximately 135 days.

At an elevation of 5,105 feet, Boundary County receives approximately 21.1 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Tomatillo during the growing season.

Boundary County, ID (Zone 6a) Short season
135 days
Last Spring Frost May 10
135 growing days
First Fall Frost September 22

Boundary County Soil Profile

Soil Type

Loam

Soil pH

6.7-8.3

Drainage

Well Drained

Tomatillo Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 6 Transplant: May 15 🍅 Harvest: Jul 17 – Sep 25
Recommended (50%) ✗ May not fit
Start indoors: Mar 15 Transplant: May 24 🍅 Harvest: Jul 26 – Oct 4
Safe Start (90%) ✗ May not fit
Start indoors: Apr 9 Transplant: Jun 18 🍅 Harvest: Aug 20 – Oct 29

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 Boundary County

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

Soil pH

Your soil pH (6.7–8.3) is more alkaline than Tomatillo prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). 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 135-day season

Sow every 6.9 weeks. Last sowing by Jun 29 to harvest before frost.

Tomatillo Water Budget

Plant needs
1.1″/week
Rainfall provides
0.7″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 640 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 1.6" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.8" 2.7" 2.1" 💧 Light watering
Jun 4.8" 1.6" 3.2" 🚿 Regular watering
Jul 4.8" 1.8" 3" 🚿 Regular watering
Aug 4.8" 1.9" 2.9" 🚿 Regular watering
Sep 4.8" 1.6" 3.2" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Boundary 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 ~1,106 GDD — county provides 2,058 GDD Excellent fit

Tomatillo Planting Timeline — Boundary County, ID

Tomatillo Planting Calendar

Activity When Date Range
Start Indoors March 15 Mar 15 – Mar 29
Transplant Outdoors May 24 May 24 – Jun 7
Direct Sow May 17 May 17 – Jun 7
Harvest July 26 Jul 26 – Oct 4

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 Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
October Harvest
November
December

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: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

135 days in Boundary County

Growing Tips for Tomatillo in Boundary County

Direct sow Tomatillo outdoors after May 10 in Boundary 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.

Boundary County receives only 21" of rain annually. Tomatillo needs consistent moisture — 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 Boundary County, ID?

Boundary County is in Zone 6a with an average last frost of May 10. Plan your Tomatillo planting based on this frost date — see the calendar above for exact timing.

What planting zone is Boundary County, ID?

Boundary County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 10 and first fall frost is September 22.

When should I plant Tomatillo in Boundary County, ID?

In Boundary County, ID, plant Tomatillo after the last frost (around May 10) and before the first frost (around September 22). Best results when soil holds above 50°F.

What growing zone is Boundary County, ID for Tomatillo?

Boundary County sits in USDA Zone 6a. Tomatillo grows reliably in zones 4a through 11b, so it's a good fit here.

Can Tomatillo grow in Boundary County's climate?

Yes — Tomatillo grows well in Boundary County's temperate climate. Boundary County averages a 135-day frost-free season, with last frost around May 10 and first frost around September 22.

🌱

Your Boundary County Garden Planner — Free

A 22-page printable planner built for Boundary County (Zone 6a). 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 Boundary County, ID. Local conditions may vary. Last updated: August 2026.

Sources & credits

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