When to Plant Bachelor's Button in Benton County, WA
What to do in August
Welcome to August in Zone 7b. These are the moves that will have the biggest impact on your growing season.
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.
Benton County, Washington is in USDA Zone 7b. The average last spring frost is April 3 and the first fall frost is October 27, giving you a growing season of approximately 207 days.
At an elevation of 2,633 feet, Benton County receives approximately 22.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Bachelor's Button during the growing season.
Benton County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.3
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 Benton County
How your county's soil matches Bachelor's Button's growing requirements.
Soil pH
Your soil pH (5.5–6.3) is more acidic than Bachelor's Button prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Benton County is excellent for Bachelor's Button — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.6%) — 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 Jul 29 to harvest before frost.
For a dedicated fall crop, sow by Sep 01.
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 | — | 3.2" | 0" | ❄️ Dormant |
| Feb | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| May | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Jun | 2.2" | 0.9" | 1.3" | 🚿 Regular watering |
| Jul | 2.2" | 0.4" | 1.8" | 🚿 Regular watering |
| Aug | 2.2" | 0.4" | 1.8" | 🚿 Regular watering |
| Sep | 2.2" | 0.8" | 1.4" | 🚿 Regular watering |
| Oct | 2.2" | 2" | 0.2" | 💧 Light watering |
| Nov | — | 3.7" | 0" | ❄️ Dormant |
| Dec | — | 3.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Benton 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 — Benton County, WA
Bachelor's Button Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 20 | Feb 20 – Mar 6 |
| Transplant Outdoors | April 3 | Apr 3 – Apr 17 |
| Direct Sow | February 27 | Feb 27 – Mar 20 |
| Bloom | June 5 | Jun 5 – Sep 11 |
| Fall Sowing | September 1 | Sep 1 – Sep 15 |
Plant 0.3" deep · 12" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors Direct Sow |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors |
| May | — |
| 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 · Only during dry spells
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 7b
📆 Growing Season
207 days in Benton County
Growing Tips for Bachelor's Button in Benton County
Direct sow Bachelor's Button outdoors after April 03 in Benton 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.
Benton County receives only 22" of rain annually. Bachelor's Button needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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 Benton County, WA?
Benton County is in Zone 7b with an average last frost of April 3. Plan your Bachelor's Button planting based on this frost date — see the calendar above for exact timing.
What planting zone is Benton County, WA?
Benton County, Washington is in USDA Hardiness Zone 7b. The average last spring frost is April 3 and first fall frost is October 27.
Your Benton County Garden Planner — Free
A 22-page printable planner built for Benton County (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.