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When to Plant Sunflower in Wrangell City and Borough, AK

Wrangell City and Borough, Alaska Zone 7b May

Your May planting checklist for Wrangell City and Borough, Alaska

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 23
Avg. first frost October 20
Soil temp (4") 62°F
Watering High
Pest pressure Moderate
Daylight 16.1 hrs
  1. Move sunflower from tray to bed

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

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

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Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.

Wrangell City and Borough, Alaska is in USDA Zone 7b. The average last spring frost is April 23 and the first fall frost is October 20, giving you a growing season of approximately 180 days.

At an elevation of 1,533 feet, Wrangell City and Borough receives approximately 35.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 59°F, so choose short-season varieties of Sunflower to ensure they mature before fall.

Wrangell City and Borough, AK (Zone 7b) Moderate season
180 days
Last Spring Frost April 23
180 growing days
First Fall Frost October 20

Wrangell City and Borough Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (43 days to spare)
Start indoors: Feb 26 Transplant: Apr 30 🍅 Harvest: Jul 9 – Aug 27
Recommended (50%) ✓ Fits season (47 days to spare)
Start indoors: Mar 5 Transplant: May 7 🍅 Harvest: Jul 16 – Sep 3
Safe Start (90%) ✓ Fits season (48 days to spare)
Start indoors: Mar 24 Transplant: May 26 🍅 Harvest: Aug 4 – Sep 22

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 Wrangell City and Borough

How your county's soil matches Sunflower's growing requirements.

Soil pH

Your soil pH (5.1–6.5) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Wrangell City and Borough is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Sunflower prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.

Organic Matter

Organic matter is excellent (6.1%) — Sunflower will thrive.

How to Plant Sunflower

1"
Planting Depth
18"
Between Plants
30"
Between Rows

Succession Planting Sunflower

2
successive plantings in your 180-day season

Sow every 8 weeks. Last sowing by Jul 12 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Sunflower

Sunflower needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Sunflower Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 2.2" 1.1" 1.1" 🚿 Regular watering
May 2.2" 1.4" 0.8" 💧 Light watering
Jun 2.2" 2.9" 0" ✅ Rainfall sufficient
Jul 2.2" 4.4" 0" ✅ Rainfall sufficient
Aug 2.2" 6.2" 0" ✅ Rainfall sufficient
Sep 2.2" 5.4" 0" ✅ Rainfall sufficient
Oct 2.2" 4.8" 0" ✅ Rainfall sufficient
Nov 2.9" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Wrangell City and Borough). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Sunflower 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.

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

Sunflower Planting Timeline — Wrangell City and Borough, AK

Sunflower Planting Calendar

Activity When Date Range
Start Indoors March 5 Mar 5 – Mar 19
Transplant Outdoors May 7 May 7 – May 21
Direct Sow April 30 Apr 30 – May 21
Harvest July 16 Jul 16 – Sep 3

Plant 1" deep · 18" apart · Rows 30" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7b

📆 Growing Season

180 days in Wrangell City and Borough

Growing Tips for Sunflower in Wrangell City and Borough

Direct sow Sunflower outdoors after April 23 in Wrangell City and Borough when soil has warmed and frost danger has passed.

Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunflower in Wrangell City and Borough, AK?

Wrangell City and Borough is in Zone 7b with an average last frost of April 23. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Wrangell City and Borough, AK?

Wrangell City and Borough, Alaska is in USDA Hardiness Zone 7b. The average last spring frost is April 23 and first fall frost is October 20.

🌱

Your Wrangell City and Borough Garden Planner — Free

A 24-page printable planner built for Wrangell City and 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.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Wrangell City and 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.