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When to Plant Black Beans in Los Alamos County, NM

Los Alamos County, New Mexico Zone 7a May

Your May planting checklist for Los Alamos County, New Mexico

Each item below is timed to Los Alamos County, New Mexico's frost dates and soil temperatures. Skip nothing, stress about nothing.

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. Put black beans seeds straight in the ground

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

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Black beans are a warm-season legume producing small, dark, protein-rich beans that are a staple in Latin American and Caribbean cuisines.

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 Black Beans during the growing season. Sandy soil warms quickly in spring — great for early planting — but Black Beans will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Black Beans 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 (9 days to spare)
Transplant: May 2 🍅 Harvest: Aug 1 – Sep 19
Recommended (50%) ✓ Fits season (10 days to spare)
Transplant: May 10 🍅 Harvest: Aug 9 – Sep 27
Safe Start (90%) ✓ Fits season (10 days to spare)
Transplant: May 26 🍅 Harvest: Aug 25 – Oct 13

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 Black Beans's growing requirements.

Soil pH

Your soil pH (7.0–8.6) is more alkaline than Black Beans prefers (6.0–7.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Black Beans.

Organic Matter

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

How to Plant Black Beans

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
1.2″/week
Watering frequency 2-3 times/week
Season total 1,540 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Black Beans

Black Beans needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Black Beans 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 4.3" 0.3" 4" 🚿 Regular watering
Jun 4.3" 0.4" 3.9" 🚿 Regular watering
Jul 4.3" 1.9" 2.4" 🚿 Regular watering
Aug 4.3" 2.4" 1.9" 💧 Light watering
Sep 4.3" 1.7" 2.6" 🚿 Regular watering
Oct 4.3" 1.1" 3.2" 🚿 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.

Black Beans 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.

Black Beans needs ~1,601 GDD — county provides 2,287 GDD Excellent fit

Black Beans Planting Timeline — Los Alamos County, NM

Black Beans Planting Calendar

Activity When Date Range
Direct Sow May 17 May 17 – Jun 7
Harvest August 16 Aug 16 – Oct 4

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7a

📆 Growing Season

150 days in Los Alamos County

Growing Tips for Black Beans in Los Alamos County

Direct sow Black Beans 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 Black Beans with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Common pests for Black Beans in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

Los Alamos County receives only 12" of rain annually. Black Beans needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow after last frost. Provide support for climbing varieties. Allow pods to dry fully on the vine before harvesting. Thresh dried pods by hand or in a pillowcase.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Black Beans in Los Alamos County, NM?

Los Alamos County is in Zone 7a with an average last frost of May 10. Plan your Black Beans 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.

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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.