When to Plant Sunflower in Island County, WA
May to-do list for Island County, Washington
Your Island County, Washington 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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Start sunflower indoors
Your window is short. These crops want several weeks of indoor growth before they go outside.
Get ahead of June
- First harvests: sunflower
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.
Island County, Washington is in USDA Zone 8b. The average last spring frost is March 30 and the first fall frost is November 3, giving you a growing season of approximately 218 days.
At an elevation of 9 feet, Island County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Sunflower during the growing season.
Island County Soil Profile
Soil Type
Silt Loam
Soil pH
5.6-6.7
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 Island County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (5.6–6.7) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Island County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.3%) — Sunflower will thrive.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Jul 26 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 | — | 6.8" | 0" | ❄️ Dormant |
| Feb | — | 4.7" | 0" | ❄️ Dormant |
| Mar | 2.2" | 4.5" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 2.3" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Jul | 2.2" | 0.7" | 1.5" | 🚿 Regular watering |
| Aug | 2.2" | 0.8" | 1.4" | 🚿 Regular watering |
| Sep | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Oct | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 7" | 0" | ✅ Rainfall sufficient |
| Dec | — | 7.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Island County). 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 — Island County, WA
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 9 | Feb 9 – Feb 23 |
| Transplant Outdoors | April 13 | Apr 13 – Apr 27 |
| Direct Sow | April 6 | Apr 6 – Apr 27 |
| Harvest | June 22 | Jun 22 – Aug 10 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| 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: acceptable
🗺️ USDA Zone
Zone 8b
📆 Growing Season
218 days in Island County
Growing Tips for Sunflower in Island County
Direct sow Sunflower outdoors after March 30 in Island County 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 Island County, WA?
Island County is in Zone 8b with an average last frost of March 30. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Island County, WA?
Island County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is March 30 and first fall frost is November 3.
Your Island County Garden Planner — Free
A 24-page printable planner built for Island County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.