When to Plant Sweet Corn in Kenai Peninsula Borough, AK
May to-do list for Kenai Peninsula Borough, Alaska
We've pulled the most time-sensitive tasks for Kenai Peninsula Borough, Alaska this May and put them front and centre. Tackle them in order.
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Put sweet corn seeds straight in the ground
These tolerate cool soil, so you're not gambling by sowing now.
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.
Kenai Peninsula Borough, Alaska is in USDA Zone 5a. The average last spring frost is May 17 and the first fall frost is September 25, giving you a growing season of approximately 131 days.
At an elevation of 1,824 feet, Kenai Peninsula Borough receives approximately 55.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 60°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.
Kenai Peninsula Borough Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.8
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 Kenai Peninsula Borough
How your county's soil matches Sweet Corn's growing requirements.
Soil pH
Your soil pH (5.2–6.8) overlaps with Sweet Corn's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Kenai Peninsula Borough is excellent for Sweet Corn — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (6.6%) — Sweet Corn will thrive.
How to Plant Sweet Corn
Succession Planting Sweet Corn
Sow every 6.9 weeks. Last sowing by Jun 27 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 | — | 3.2" | 0" | ❄️ Dormant |
| Feb | — | 2.4" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 1.5" | 0" | ❄️ Dormant |
| May | 6.5" | 2.3" | 4.2" | 🚿 Regular watering |
| Jun | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| Jul | 6.5" | 7.6" | 0" | ✅ Rainfall sufficient |
| Aug | 6.5" | 8.3" | 0" | ✅ Rainfall sufficient |
| Sep | 6.5" | 10.1" | 0" | ✅ Rainfall sufficient |
| Oct | — | 7" | 0" | ❄️ Dormant |
| Nov | — | 4.3" | 0" | ❄️ Dormant |
| Dec | — | 3.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Kenai Peninsula 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 — Kenai Peninsula Borough, AK
Sweet Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 24 | May 24 – Jun 14 |
| Harvest | July 26 | Jul 26 – Sep 6 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| 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: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
131 days in Kenai Peninsula Borough
Growing Tips for Sweet Corn in Kenai Peninsula Borough
Direct sow Sweet Corn outdoors after May 17 in Kenai Peninsula 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 Kenai Peninsula Borough, AK?
Kenai Peninsula Borough is in Zone 5a with an average last frost of May 17. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Kenai Peninsula Borough, AK?
Kenai Peninsula Borough, Alaska is in USDA Hardiness Zone 5a. The average last spring frost is May 17 and first fall frost is September 25.
Your Kenai Peninsula Borough Garden Planner — Free
A 24-page printable planner built for Kenai Peninsula Borough (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.