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When to Plant Corn in Sierra County, NM

Sierra County, New Mexico Zone 8a May

Sierra County, New Mexico gardeners: here's your May plan

We've pulled the most time-sensitive tasks for Sierra County, New Mexico this May and put them front and centre. Tackle them in order.

Avg. last frost April 15
Avg. first frost October 26
Soil temp (4") 55°F
Watering Critical
Pest pressure Moderate
Daylight 13.7 hrs
To set up a strong June, finish these tasks
  • First harvests: corn

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Corn is a warm-season grass grown for its sweet ears, which are best eaten soon after harvest. It is wind-pollinated and must be planted in blocks for good kernel fill.

Sierra County, New Mexico is in USDA Zone 8a. The average last spring frost is April 15 and the first fall frost is October 26, giving you a growing season of approximately 194 days.

At an elevation of 4,898 feet, Sierra County receives approximately 17.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 88°F, providing good warmth for Corn during the growing season. Sandy soil warms quickly in spring — great for early planting — but Corn will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Corn successfully. Mulch heavily to conserve soil moisture.

Sierra County, NM (Zone 8a) Moderate season
194 days
Last Spring Frost April 15
194 growing days
First Fall Frost October 26
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Sierra County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.3-8.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (86 days to spare)
Transplant: Mar 30 🍅 Harvest: Jun 1 – Jul 27
Recommended (50%) ✓ Fits season (75 days to spare)
Transplant: Apr 15 🍅 Harvest: Jun 17 – Aug 12
Safe Start (90%) ✓ Fits season (80 days to spare)
Transplant: May 4 🍅 Harvest: Jul 6 – Aug 31

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 Sierra County

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

Soil pH

Your soil pH (7.3–8.5) is more alkaline than Corn prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Corn.

Organic Matter

Organic matter is low (0.7%). Add 2-3 inches of compost before planting Corn.

How to Plant Corn

1"
Planting Depth
12"
Between Plants
36"
Between Rows

Succession Planting Corn

3
successive plantings in your 194-day season

Sow every 6.9 weeks. Last sowing by Jul 18 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.4″/week
You supply
1.9″/week
Watering frequency 2-3 times/week
Season total 3,260 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Corn

Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Corn Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 6.5" 0.6" 5.9" 🚿 Regular watering
May 6.5" 0.4" 6.1" 🚿 Regular watering
Jun 6.5" 0.5" 6" 🚿 Regular watering
Jul 6.5" 2.7" 3.8" 🚿 Regular watering
Aug 6.5" 3.3" 3.2" 💧 Light watering
Sep 6.5" 2.3" 4.2" 🚿 Regular watering
Oct 6.5" 1.7" 4.8" 🚿 Regular watering
Nov 1" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Sierra County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Corn 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.

Corn needs ~1,280 GDD — county provides 3,104 GDD Excellent fit

Corn Planting Timeline — Sierra County, NM

Corn Planting Calendar

Activity When Date Range
Direct Sow April 22 Apr 22 – May 13
Harvest June 24 Jun 24 – Aug 19

Plant 1" deep · 12" apart · Rows 36" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

60–100 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 8a

📆 Growing Season

194 days in Sierra County

Growing Tips for Corn in Sierra County

Direct sow Corn outdoors after April 15 in Sierra County when soil has warmed and frost danger has passed.

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

Common pests for Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.

Sierra County receives only 17" of rain annually. Corn needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Plant in blocks of at least 4 rows rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Celery

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Corn in Sierra County, NM?

Sierra County is in Zone 8a with an average last frost of April 15. Plan your Corn planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sierra County, NM?

Sierra County, New Mexico is in USDA Hardiness Zone 8a. The average last spring frost is April 15 and first fall frost is October 26.

🌱

Your Sierra County Garden Planner — Free

A 24-page printable planner built for Sierra County (Zone 8a). 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 Sierra 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.