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When to Plant Tomatillo in Los Alamos County, NM

Los Alamos County, New Mexico Zone 7a May

May to-do list for Los Alamos County, New Mexico

Here's what deserves your attention in Los Alamos County, New Mexico this month. Everything below is tailored to Zone 7a and timed around your local frost dates.

Avg. last frost May 10
Avg. first frost October 7
Soil temp (4") 49°F
Watering Critical
Pest pressure Low
Daylight 13.9 hrs
  1. Move tomatillo from tray to bed

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Outdoor sowing time: tomatillo

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

Before June arrives, get these ready
  • Starting indoors: 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.

Los Alamos County, New Mexico is in USDA Zone 7a. The average last spring frost is May 10 and the first fall frost is October 7, giving you a growing season of approximately 150 days.

At an elevation of 5,220 feet, Los Alamos County receives approximately 12.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for Tomatillo during the growing season. Sandy soil warms quickly in spring — great for early planting — but Tomatillo will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Tomatillo successfully. Mulch heavily to conserve soil moisture.

Los Alamos County, NM (Zone 7a) Moderate season
150 days
Last Spring Frost May 10
150 growing days
First Fall Frost October 7

Los Alamos County Soil Profile

Soil Type

Sandy Loam

Soil pH

7-8.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (2 days to spare)
Start indoors: Mar 14 Transplant: May 16 🍅 Harvest: Jul 18 – Sep 26
Recommended (50%) ✓ Fits season (3 days to spare)
Start indoors: Mar 22 Transplant: May 24 🍅 Harvest: Jul 26 – Oct 4
Safe Start (90%) ✓ Fits season (3 days to spare)
Start indoors: Apr 7 Transplant: Jun 9 🍅 Harvest: Aug 11 – Oct 20

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 Los Alamos County

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

Soil pH

Your soil pH (7.0–8.6) is more alkaline than Tomatillo prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Los Alamos County warms quickly in spring but drains fast. Tomatillo will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Tomatillo.

Organic Matter

Organic matter is low (0.8%). Add 2-3 inches of compost before planting Tomatillo.

How to Plant Tomatillo

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

Succession Planting Tomatillo

2
successive plantings in your 150-day season

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

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.3″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 1,748 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 0.9" 0" ❄️ Dormant
Feb 0.6" 0" ❄️ Dormant
Mar 0.8" 0" ❄️ Dormant
Apr 0.4" 0" ❄️ Dormant
May 4.8" 0.3" 4.5" 🚿 Regular watering
Jun 4.8" 0.4" 4.4" 🚿 Regular watering
Jul 4.8" 1.9" 2.9" 🚿 Regular watering
Aug 4.8" 2.4" 2.4" 🚿 Regular watering
Sep 4.8" 1.7" 3.1" 🚿 Regular watering
Oct 4.8" 1.1" 3.7" 🚿 Regular watering
Nov 0.7" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Los Alamos 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 2,287 GDD Excellent fit

Tomatillo Planting Timeline — Los Alamos County, NM

Tomatillo Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
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 Start Indoors
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 · 2-3 times/week

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7a

📆 Growing Season

150 days in Los Alamos County

Growing Tips for Tomatillo in Los Alamos County

Direct sow Tomatillo outdoors after May 10 in Los Alamos County when soil has warmed and frost danger has passed.

Sandy soil in Los Alamos County dries quickly — mulch Tomatillo with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Common pests for Tomatillo in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

Los Alamos County receives only 12" 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 Los Alamos County, NM?

Los Alamos County is in Zone 7a 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 Los Alamos County, NM?

Los Alamos County, New Mexico is in USDA Hardiness Zone 7a. The average last spring frost is May 10 and first fall frost is October 7.

🌱

Your Los Alamos County Garden Planner — Free

A 24-page printable planner built for Los Alamos County (Zone 7a). 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 Los Alamos County, NM. 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.