When to Plant Bachelor's Button in Snohomish County, WA
This month in Snohomish County, Washington
If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.
Bachelor's Button (Centaurea cyanus), also called cornflower, is a carefree cool-season annual best known for its vivid cobalt-blue flowers — one of the truest blues in the annual garden. It tolerates light frosts, self-seeds prolifically, and thrives in poor to average soils. A traditional cut flower and pollinator magnet, it has been cultivated in gardens for centuries.
Snohomish County, Washington is in USDA Zone 8b. The average last spring frost is March 25 and the first fall frost is November 2, giving you a growing season of approximately 222 days.
At an elevation of 230 feet, Snohomish County receives approximately 50.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Bachelor's Button during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Bachelor's Button root diseases.
Snohomish County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.8
Drainage
Well Drained
Bachelor's Button 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 Snohomish County
How your county's soil matches Bachelor's Button's growing requirements.
Soil pH
Your soil pH (5.7–6.8) overlaps with Bachelor's Button's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Snohomish County is excellent for Bachelor's Button — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.4%) — Bachelor's Button will thrive.
How to Plant Bachelor's Button
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Bachelor's Button
Sow every 6.9 weeks. Last sowing by Aug 04 to harvest before frost.
For a dedicated fall crop, sow by Sep 07.
Bachelor's Button Water Budget
Monthly Watering Guide for Bachelor's Button
Bachelor's Button 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 | Bachelor's Button Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 7.7" | 0" | ❄️ Dormant |
| Feb | — | 5.6" | 0" | ❄️ Dormant |
| Mar | 2.2" | 5" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Jul | 2.2" | 0.7" | 1.5" | 🚿 Regular watering |
| Aug | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Sep | 2.2" | 2" | 0.2" | 💧 Light watering |
| Oct | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 8" | 0" | ✅ Rainfall sufficient |
| Dec | — | 8.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Snohomish County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Bachelor's Button 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.
Bachelor's Button Planting Timeline — Snohomish County, WA
Bachelor's Button Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 4 | Mar 4 – Mar 18 |
| Direct Sow | February 4 | Feb 4 – Feb 25 |
| Bloom | May 6 | May 6 – Sep 2 |
| Fall Sowing | September 7 | Sep 7 – Sep 21 |
Plant 0.3" deep · 12" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Direct Sow |
| March | Transplant Outdoors |
| April | — |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Fall Sowing Bloom |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 8b
📆 Growing Season
222 days in Snohomish County
Growing Tips for Bachelor's Button in Snohomish County
Direct sow Bachelor's Button outdoors after March 25 in Snohomish County when soil has warmed and frost danger has passed.
Common pests for Bachelor's Button in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct-sow in early spring as soon as soil can be worked; seeds need a brief cold period for best germination (refrigerate for a few days before planting if spring arrives quickly). In zones 6+, fall-sow for the earliest spring bloom. Thin to 12 inches; do not over-fertilize — too much nitrogen produces foliage at the expense of flowers. Deadhead to prolong blooming or allow self-seeding for a naturalized colony.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Bachelor's Button in Other Locations
Frequently Asked Questions
When should I plant Bachelor's Button in Snohomish County, WA?
Snohomish County is in Zone 8b with an average last frost of March 25. Plan your Bachelor's Button planting based on this frost date — see the calendar above for exact timing.
What planting zone is Snohomish County, WA?
Snohomish County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is March 25 and first fall frost is November 2.
Your Snohomish County Garden Planner — Free
A 22-page printable planner built for Snohomish 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.