When to Plant Sunflower in North Slope Borough, AK
Your May gardening checklist
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in North Slope Borough, Alaska.
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.
North Slope Borough, Alaska is in USDA Zone 2b. The average last spring frost is May 27 and the first fall frost is July 31, giving you a growing season of approximately 65 days.
At an elevation of 2,600 feet, North Slope Borough receives approximately 16.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 69°F, so choose short-season varieties of Sunflower to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Sunflower successfully. Mulch heavily to conserve soil moisture.
North Slope Borough Soil Profile
Soil Type
Silt Loam
Soil pH
4.9-6.7
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 North Slope Borough
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (4.9–6.7) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in North Slope 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 (5.7%) — Sunflower will thrive.
How to Plant Sunflower
Plant Water Budget
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 | — | 0.7" | 0" | ❄️ Dormant |
| Feb | — | 0.6" | 0" | ❄️ Dormant |
| Mar | — | 0.6" | 0" | ❄️ Dormant |
| Apr | — | 0.5" | 0" | ❄️ Dormant |
| May | 2.2" | 0.7" | 1.5" | 🚿 Regular watering |
| Jun | 2.2" | 1.2" | 1" | 💧 Light watering |
| Jul | 2.2" | 2.2" | 0" | ✅ Rainfall sufficient |
| Aug | — | 2.4" | 0" | ❄️ Dormant |
| Sep | — | 3.1" | 0" | ❄️ Dormant |
| Oct | — | 2.2" | 0" | ❄️ Dormant |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Jul in North Slope 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 Planting Timeline — North Slope Borough, AK
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 25 | Mar 25 – Apr 8 |
| Transplant Outdoors | June 17 | Jun 17 – Jul 1 |
| Direct Sow | June 10 | Jun 10 – Jul 1 |
| Harvest | August 26 | Aug 26 – Oct 14 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors Direct Sow |
| July | Transplant Outdoors Direct Sow |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| 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 2b
📆 Growing Season
65 days in North Slope Borough
Growing Tips for Sunflower in North Slope Borough
Your 65.0-day growing season in North Slope Borough is tight for Sunflower (70.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
North Slope Borough receives only 17" of rain annually. Sunflower needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in North Slope Borough, AK?
North Slope Borough is in Zone 2b with an average last frost of May 27. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is North Slope Borough, AK?
North Slope Borough, Alaska is in USDA Hardiness Zone 2b. The average last spring frost is May 27 and first fall frost is July 31.
Your North Slope Borough Garden Planner — Free
A 24-page printable planner built for North Slope Borough (Zone 2b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.