When to Plant Sweet Corn in Ketchikan Gateway Borough, AK
May in the garden — Ketchikan Gateway Borough, Alaska
A quick May briefing for Ketchikan Gateway Borough, Alaska gardeners — what's urgent, what's next, and what can wait.
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Direct-sow sweet corn
Your soil is 64°F — warm enough for these to germinate without babying.
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.
Ketchikan Gateway Borough, Alaska is in USDA Zone 7b. The average last spring frost is April 25 and the first fall frost is October 19, giving you a growing season of approximately 177 days.
At an elevation of 1,212 feet, Ketchikan Gateway Borough receives approximately 57.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 65°F, so choose short-season varieties of Sweet Corn to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sweet Corn root diseases.
Ketchikan Gateway Borough Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.7
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 Ketchikan Gateway Borough
How your county's soil matches Sweet Corn's growing requirements.
Soil pH
Your soil pH (5.0–6.7) is more acidic than Sweet Corn prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Ketchikan Gateway Borough 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 excellent (5.9%) — Sweet Corn will thrive.
How to Plant Sweet Corn
Succession Planting Sweet Corn
Sow every 6.9 weeks. Last sowing by Jul 21 to harvest before frost.
Plant Water Budget
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 | — | 2.8" | 0" | ❄️ Dormant |
| Feb | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 1.8" | 0" | ❄️ Dormant |
| Apr | 6.5" | 2" | 4.5" | 🚿 Regular watering |
| May | 6.5" | 2.4" | 4.1" | 🚿 Regular watering |
| Jun | 6.5" | 4.5" | 2" | 💧 Light watering |
| Jul | 6.5" | 6.6" | 0" | ✅ Rainfall sufficient |
| Aug | 6.5" | 9.5" | 0" | ✅ Rainfall sufficient |
| Sep | 6.5" | 11" | 0" | ✅ Rainfall sufficient |
| Oct | 6.5" | 6.6" | 0" | ✅ Rainfall sufficient |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 3.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Ketchikan Gateway Borough). 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 — Ketchikan Gateway Borough, AK
Sweet Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 2 | May 2 – May 23 |
| Harvest | July 4 | Jul 4 – Aug 15 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 7b
📆 Growing Season
177 days in Ketchikan Gateway Borough
Growing Tips for Sweet Corn in Ketchikan Gateway Borough
Direct sow Sweet Corn outdoors after April 25 in Ketchikan Gateway Borough 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 Ketchikan Gateway Borough, AK?
Ketchikan Gateway Borough is in Zone 7b with an average last frost of April 25. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Ketchikan Gateway Borough, AK?
Ketchikan Gateway Borough, Alaska is in USDA Hardiness Zone 7b. The average last spring frost is April 25 and first fall frost is October 19.
Your Ketchikan Gateway Borough Garden Planner — Free
A 24-page printable planner built for Ketchikan Gateway Borough (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.