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When to plant Corn in Keyes, CA

For Corn in Keyes, the safe spring window opens around March 3 and closes around March 24. Last expected frost is February 24, first fall frost November 28, giving a 278-day growing season.

When to Plant Corn in Keyes, CA

Corn
Stanislaus County, California Zone 9b June

June in Stanislaus County, California — your action list

Here's what deserves your attention in Stanislaus County, California this month. Everything below is tailored to Zone 9b and timed around your local frost dates.

Avg. last frost February 24
Avg. first frost November 28
Soil temp (4") 80°F
Watering Critical
Pest pressure High
Daylight 14.6 hrs
  1. Basket week: corn

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

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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.

Keyes, California is in USDA Zone 9b. The average last spring frost is February 24 and the first fall frost is November 28, giving you a growing season of approximately 277 days.

At an elevation of 2,887 feet, Stanislaus County receives approximately 15.2 inches of rainfall annually with predominantly loam soil. Summer highs average 94°F, providing good warmth for Corn during the growing season. With low rainfall, drip irrigation is essential for growing Corn successfully. Mulch heavily to conserve soil moisture.

Keyes, CA (Zone 9b) Year-round
277 days
Last Spring Frost February 24
277 growing days
First Fall Frost November 28

Keyes Soil Profile

Soil Type

Loam

Soil pH

6.5-7.7

Drainage

Well Drained

Corn Planting Risk Windows

Early Start (70% safe) ✓ Fits season (170 days to spare)
Transplant: Feb 6 🍅 Harvest: Apr 10 – Jun 5
Recommended (50%) ✓ Fits season (158 days to spare)
Transplant: Feb 24 🍅 Harvest: Apr 28 – Jun 23
Safe Start (90%) ✓ Fits season (123 days to spare)
Transplant: Apr 18 🍅 Harvest: Jun 20 – Aug 15

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 Keyes

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

Soil pH

Your soil pH (6.5–7.7) is more alkaline than Corn prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Corn.

How to Plant Corn

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

Succession Planting Corn

5
successive plantings in your 277-day season

Sow every 6.9 weeks. Last sowing by Aug 20 to harvest before frost.

Corn Water Budget

Plant needs
1.5″/week
Rainfall provides
0.2″/week
You supply
1.5″/week
Watering frequency 2-3 times/week
Season total 3,772 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 3.1" 0" ❄️ Dormant
Feb 6.5" 3.5" 3" 💧 Light watering
Mar 6.5" 2.1" 4.4" 🚿 Regular watering
Apr 6.5" 1.3" 5.2" 🚿 Regular watering
May 6.5" 0.5" 6" 🚿 Regular watering
Jun 6.5" 0.1" 6.4" 🚿 Regular watering
Jul 6.5" 0" 6.5" 🚿 Regular watering
Aug 6.5" 0" 6.5" 🚿 Regular watering
Sep 6.5" 0.2" 6.3" 🚿 Regular watering
Oct 6.5" 0.7" 5.8" 🚿 Regular watering
Nov 6.5" 1.5" 5" 🚿 Regular watering
Dec 2.2" 0" ❄️ Dormant

Water needs are for active growing months only (Feb–Nov in Stanislaus 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 ~1,640 GDD — county provides 5,699 GDD Excellent fit

Corn Planting Timeline — Keyes, CA

Corn Planting Calendar

Activity When Date Range
Direct Sow March 3 Mar 3 – Mar 24
Harvest May 5 May 5 – Jun 30

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

Month-by-Month Timeline

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

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 9b

📆 Growing Season

277 days in Stanislaus County

Growing Tips for Corn in Keyes

Direct sow Corn outdoors after February 24 in Stanislaus County when soil has warmed and frost danger has passed.

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

Stanislaus County receives only 15" 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 →

When should I plant Corn in Keyes, CA?

In Keyes, CA, plant Corn after the last frost (around February 24) and before the first frost (around November 28). Best results when soil holds above 50°F.

What growing zone is Keyes, CA for Corn?

Keyes sits in USDA Zone 9b. Corn grows reliably in zones 3a through 11b, so it's a good fit here.

Can Corn grow in Keyes's climate?

Yes — Corn grows well in Keyes's temperate climate. Keyes averages a 278-day frost-free season, with last frost around February 24 and first frost around November 28.

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Your Stanislaus County Garden Planner — Free

A 22-page printable planner built for Stanislaus County (Zone 9b). 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 Stanislaus County, CA. Local conditions may vary. Last updated: June 2026.