When to Plant Brussels Sprouts in Thurston County, WA
Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.
Thurston County, Washington is in USDA Zone 8a. The average last spring frost is April 15 and the first fall frost is October 29, giving you a growing season of approximately 197 days.
At an elevation of 213 feet, Thurston County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Brussels Sprouts during the growing season.
Thurston County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.6
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 Thurston County
How your county's soil matches Brussels Sprouts's growing requirements.
Soil pH
Your soil pH (5.3–6.6) is more acidic than Brussels Sprouts prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Thurston County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.6%) — Brussels Sprouts will thrive.
How to Plant Brussels Sprouts
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Plant Water Budget
Monthly Watering Guide for Brussels Sprouts
Brussels Sprouts needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.
| Month | Brussels Sprouts Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 4.9" | 0" | ❄️ Dormant |
| Feb | — | 4.6" | 0" | ❄️ Dormant |
| Mar | — | 4.2" | 0" | ❄️ Dormant |
| Apr | 3.9" | 2.7" | 1.2" | 💧 Light watering |
| May | 3.9" | 2.2" | 1.7" | 💧 Light watering |
| Jun | 3.9" | 1.4" | 2.5" | 🚿 Regular watering |
| Jul | 3.9" | 0.7" | 3.2" | 🚿 Regular watering |
| Aug | 3.9" | 0.7" | 3.2" | 🚿 Regular watering |
| Sep | 3.9" | 1.7" | 2.2" | 🚿 Regular watering |
| Oct | 3.9" | 3" | 0.9" | 💧 Light watering |
| Nov | — | 5.3" | 0" | ❄️ Dormant |
| Dec | — | 6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Thurston County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Brussels Sprouts 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.
Brussels Sprouts Planting Timeline — Thurston County, WA
Brussels Sprouts Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 11 | Mar 11 – Mar 25 |
| Transplant Outdoors | April 15 | Apr 15 – Apr 29 |
| Direct Sow | April 1 | Apr 1 – Apr 22 |
| Harvest | July 15 | Jul 15 – Sep 9 |
| Fall Sowing | August 20 | Aug 20 – Sep 3 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Fall Sowing Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.9"/week · Only during dry spells
📅 Days to Maturity
90–130 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 8a
📆 Growing Season
197 days in Thurston County
Growing Tips for Brussels Sprouts in Thurston County
Direct sow Brussels Sprouts outdoors after April 15 in Thurston County when soil has warmed and frost danger has passed.
Common pests for Brussels Sprouts in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 12-14 weeks before first fall frost. Stake tall plants to prevent toppling. Remove lower leaves as sprouts develop to improve air circulation.
Companion Planting
Good Companions
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Brussels Sprouts in Other Locations
Frequently Asked Questions
When should I plant Brussels Sprouts in Thurston County, WA?
Thurston County is in Zone 8a with an average last frost of April 15. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.
What planting zone is Thurston County, WA?
Thurston County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 15 and first fall frost is October 29.
Plan Your Garden with Confidence
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