When to Plant Bachelor's Button in Enumclaw, WA
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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.
Enumclaw, Washington is in USDA Zone 9a. The average last spring frost is April 7 and the first fall frost is October 30, giving you a growing season of approximately 206 days.
At an elevation of 258 feet, King County receives approximately 37.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Bachelor's Button during the growing season.
Enumclaw Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.4
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 Enumclaw
How your county's soil matches Bachelor's Button's growing requirements.
Soil pH
Your soil pH (5.7–6.4) overlaps with Bachelor's Button's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in King County is excellent for Bachelor's Button — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.5%) — Bachelor's Button will thrive.
How to Plant Bachelor's Button
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Bachelor's Button
Sow every 6.9 weeks. Last sowing by Aug 01 to harvest before frost.
For a dedicated fall crop, sow by Aug 21.
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 | — | 5.9" | 0" | ❄️ Dormant |
| Feb | — | 4.5" | 0" | ❄️ Dormant |
| Mar | — | 3.4" | 0" | ❄️ Dormant |
| Apr | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 2" | 0.2" | 💧 Light watering |
| Jun | 2.2" | 1.3" | 0.9" | 💧 Light watering |
| Jul | 2.2" | 0.6" | 1.6" | 🚿 Regular watering |
| Aug | 2.2" | 0.7" | 1.5" | 🚿 Regular watering |
| Sep | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Oct | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Nov | — | 5.6" | 0" | ❄️ Dormant |
| Dec | — | 5.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in King 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 — Enumclaw, WA
Bachelor's Button Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 10 | Mar 10 – Mar 24 |
| Direct Sow | February 10 | Feb 10 – Mar 3 |
| Bloom | May 5 | May 5 – Aug 25 |
| Fall Sowing | August 21 | Aug 21 – Sep 4 |
Plant 0.3" deep · 12" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Fall Sowing Bloom |
| September | Fall Sowing |
| 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 9a
📆 Growing Season
206 days in King County
Growing Tips for Bachelor's Button in Enumclaw
Direct sow Bachelor's Button outdoors after April 07 in King 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
Your King County Garden Planner — Free
A 22-page printable planner built for King County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.