Blog

When to Plant Scallions in Kenai Peninsula Borough, AK

Kenai Peninsula Borough, Alaska Zone 5a May

This month in 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.

Avg. last frost May 17
Avg. first frost September 25
Soil temp (4") 52°F
Watering High
Pest pressure Low
Daylight 16.8 hrs
  1. Harden off and plant scallions

    Your last frost (May 17) has passed. These warm-season crops can handle outdoor soil now.

  2. Scatter scallions into prepared beds

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

A few tasks this May that'll pay off in June
  • Starting indoors: scallions

Instant PDF download. No spam, unsubscribe any time.

Scallions (green onions) are mild-flavored alliums harvested for their slender green tops and white bases. They are quick-growing and perfect for succession planting.

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 Scallions to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Scallions root diseases.

Kenai Peninsula Borough, AK (Zone 5a) Short season
131 days
Last Spring Frost May 17
131 growing days
First Fall Frost September 25

Kenai Peninsula Borough Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jul 7 – Aug 4
Recommended (50%) ✓ Fits season (47 days to spare)
Start indoors: Apr 12 Transplant: May 17 🍅 Harvest: Jul 12 – Aug 9
Safe Start (90%) ✓ Fits season (47 days to spare)
Start indoors: Apr 27 Transplant: Jun 1 🍅 Harvest: Jul 27 – Aug 24

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 Scallions's growing requirements.

Soil pH

Your soil pH (5.2–6.8) overlaps with Scallions's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Kenai Peninsula Borough is excellent for Scallions — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (6.6%) — Scallions will thrive.

How to Plant Scallions

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Scallions

3
successive plantings in your 131-day season

Sow every 5.7 weeks. Last sowing by Jul 17 to harvest before frost.

For a dedicated fall crop, sow by Jul 17.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Scallions

Scallions needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Scallions 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 4.3" 2.3" 2" 💧 Light watering
Jun 4.3" 3.8" 0.5" 💧 Light watering
Jul 4.3" 7.6" 0" ✅ Rainfall sufficient
Aug 4.3" 8.3" 0" ✅ Rainfall sufficient
Sep 4.3" 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.

Scallions 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.

Scallions needs ~0 GDD — county provides 0 GDD May not mature

Scallions Planting Timeline — Kenai Peninsula Borough, AK

Scallions Planting Calendar

Activity When Date Range
Start Indoors April 12 Apr 12 – Apr 26
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 3 May 3 – May 24
Harvest July 12 Jul 12 – Aug 9
Fall Sowing July 17 Jul 17 – Jul 31

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June
July Fall Sowing Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

131 days in Kenai Peninsula Borough

Growing Tips for Scallions in Kenai Peninsula Borough

Direct sow Scallions outdoors after May 17 in Kenai Peninsula Borough when soil has warmed and frost danger has passed.

Common pests for Scallions in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow every 3 weeks for continuous harvest. Thin to 1 inch apart or grow in clusters. Harvest when pencil-thick by pulling or cutting at soil level.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Scallions in Kenai Peninsula Borough, AK?

Kenai Peninsula Borough is in Zone 5a with an average last frost of May 17. Plan your Scallions 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Kenai Peninsula Borough, AK. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.