When to Plant Sweet Corn in Colusa County, CA
Your May planting checklist for Colusa County, California
Each item below is timed to Colusa County, California's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Bring in the sweet corn
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Before June arrives, get these ready
- First harvests: sweet corn
Sweet corn is bred for high sugar content in its kernels, which convert to starch rapidly after harvest. Modern supersweet varieties hold their sweetness longer.
Colusa County, California is in USDA Zone 9b. The average last spring frost is March 6 and the first fall frost is November 28, giving you a growing season of approximately 267 days.
At an elevation of 112 feet, Colusa County receives approximately 29.8 inches of rainfall annually with predominantly loam soil. Summer highs average 94°F, providing good warmth for Sweet Corn during the growing season.
Colusa County Soil Profile
Soil Type
Loam
Soil pH
6.6-7.5
Drainage
Well Drained
Plant Planting Risk Windows
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 Colusa County
How your county's soil matches Sweet Corn's growing requirements.
Soil pH
Your soil pH (6.6–7.5) is more alkaline than Sweet Corn prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Colusa County is excellent for Sweet Corn — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Sweet Corn.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Sweet Corn.
How to Plant Sweet Corn
Succession Planting Sweet Corn
Sow every 6.9 weeks. Last sowing by Aug 30 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Sweet Corn
Sweet 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 | Sweet Corn Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 6.2" | 0" | ❄️ Dormant |
| Feb | — | 6.7" | 0" | ❄️ Dormant |
| Mar | 6.5" | 4.7" | 1.8" | 💧 Light watering |
| Apr | 6.5" | 2" | 4.5" | 🚿 Regular watering |
| May | 6.5" | 0.7" | 5.8" | 🚿 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" | 0.3" | 6.2" | 🚿 Regular watering |
| Oct | 6.5" | 1.1" | 5.4" | 🚿 Regular watering |
| Nov | 6.5" | 3" | 3.5" | 🚿 Regular watering |
| Dec | — | 4.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Colusa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sweet 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.
Sweet Corn Planting Timeline — Colusa County, CA
Sweet Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 13 | Mar 13 – Apr 3 |
| Harvest | May 15 | May 15 – Jun 26 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Direct Sow |
| April | Direct Sow |
| 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
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 9b
📆 Growing Season
267 days in Colusa County
Growing Tips for Sweet Corn in Colusa County
Direct sow Sweet Corn outdoors after March 06 in Colusa County when soil has warmed and frost danger has passed.
Common pests for Sweet Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.
General growing tips
Plant in blocks of at least 4 rows for wind pollination. Direct sow after soil is warm. Isolate supersweet varieties from other corn types to prevent cross-pollination.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sweet Corn in Other Locations
Frequently Asked Questions
When should I plant Sweet Corn in Colusa County, CA?
Colusa County is in Zone 9b with an average last frost of March 6. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Colusa County, CA?
Colusa County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 6 and first fall frost is November 28.
Your Colusa County Garden Planner — Free
A 24-page printable planner built for Colusa 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.