When to Plant Sweet Corn in Clatsop County, OR
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.
Clatsop County, Oregon is in USDA Zone 9a. The average last spring frost is April 12 and the first fall frost is November 4, giving you a growing season of approximately 206 days.
At an elevation of 412 feet, Clatsop County receives approximately 54.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Sweet Corn during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sweet Corn root diseases.
Clatsop County Soil Profile
Soil Type
Silt Loam
Soil pH
5.6-6.7
Drainage
Well Drained
Monthly Watering Guide for Sweet Corn
Sweet Corn needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Sweet Corn Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 8.4" | 0" | ❄️ Dormant |
| Feb | — | 5.2" | 0" | ❄️ Dormant |
| Mar | — | 4.8" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| May | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Jun | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Jul | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Aug | 4.3" | 1.1" | 3.2" | 🚿 Regular watering |
| Sep | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Oct | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Nov | 4.3" | 8.4" | 0" | ✅ Rainfall sufficient |
| Dec | — | 9.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Nov in Clatsop County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sweet Corn Planting Timeline — Clatsop County, OR
Sweet Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 19 | Apr 19 – May 10 |
| Harvest | June 21 | Jun 21 – Aug 2 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 9a
📆 Growing Season
206 days in Clatsop County
Growing Tips for Clatsop County
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 Clatsop County, OR?
Clatsop County is in Zone 9a with an average last frost of April 12. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clatsop County, OR?
Clatsop County, Oregon is in USDA Hardiness Zone 9a. The average last spring frost is April 12 and first fall frost is November 4.
Your Clatsop County Garden Planner — Free
A 22-page printable planner built for Clatsop County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.