When to Plant Sunflower in Haines Borough, AK
What to do in May
Your Haines Borough, Alaska garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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Get sunflower in the ground
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
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Put sunflower seeds straight in the ground
These tolerate cool soil, so you're not gambling by sowing now.
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.
Haines Borough, Alaska is in USDA Zone 5b. The average last spring frost is May 7 and the first fall frost is September 29, giving you a growing season of approximately 145 days.
At an elevation of 1,921 feet, Haines Borough receives approximately 57.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 68°F, so choose short-season varieties of Sunflower to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sunflower root diseases.
Haines Borough Soil Profile
Soil Type
Silt Loam
Soil pH
4.9-6.4
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 Haines Borough
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (4.9–6.4) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Haines 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 (6.6%) — Sunflower will thrive.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Jun 21 to harvest before frost.
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 | — | 2.8" | 0" | ❄️ Dormant |
| Feb | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 2" | 0" | ❄️ Dormant |
| May | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 8.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 8.5" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 10.6" | 0" | ✅ Rainfall sufficient |
| Oct | — | 6.5" | 0" | ❄️ Dormant |
| Nov | — | 4.1" | 0" | ❄️ Dormant |
| Dec | — | 3.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Haines 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 — Haines Borough, AK
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 12 | Mar 12 – Mar 26 |
| Transplant Outdoors | May 21 | May 21 – Jun 4 |
| Direct Sow | May 14 | May 14 – Jun 4 |
| Harvest | July 30 | Jul 30 – Sep 17 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| 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 5b
📆 Growing Season
145 days in Haines Borough
Growing Tips for Sunflower in Haines Borough
Direct sow Sunflower outdoors after May 07 in Haines 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
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Haines Borough, AK?
Haines Borough is in Zone 5b with an average last frost of May 7. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Haines Borough, AK?
Haines Borough, Alaska is in USDA Hardiness Zone 5b. The average last spring frost is May 7 and first fall frost is September 29.
Your Haines Borough Garden Planner — Free
A 24-page printable planner built for Haines Borough (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.