When to Plant Brussels Sprouts in Kitsap County, WA
Kitsap County, Washington gardeners: here's your May plan
A quick May briefing for Kitsap County, Washington gardeners — what's urgent, what's next, and what can wait.
June prep starts now
- First harvests: brussels sprouts
Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.
Kitsap County, Washington is in USDA Zone 9a. The average last spring frost is March 25 and the first fall frost is November 5, giving you a growing season of approximately 225 days.
At an elevation of 264 feet, Kitsap County receives approximately 38 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Brussels Sprouts during the growing season.
Kitsap County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.3
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 Kitsap County
How your county's soil matches Brussels Sprouts's growing requirements.
Soil pH
Your soil pH (5.3–6.3) is more acidic than Brussels Sprouts prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Kitsap County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Brussels Sprouts will thrive.
How to Plant Brussels Sprouts
Fall planting: Sow 8 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 | — | 5.1" | 0" | ❄️ Dormant |
| Feb | — | 4.5" | 0" | ❄️ Dormant |
| Mar | 3.9" | 4.3" | 0" | ✅ Rainfall sufficient |
| Apr | 3.9" | 2.7" | 1.2" | 💧 Light watering |
| May | 3.9" | 2" | 1.9" | 💧 Light watering |
| Jun | 3.9" | 1.3" | 2.6" | 🚿 Regular watering |
| Jul | 3.9" | 0.7" | 3.2" | 🚿 Regular watering |
| Aug | 3.9" | 0.7" | 3.2" | 🚿 Regular watering |
| Sep | 3.9" | 1.4" | 2.5" | 🚿 Regular watering |
| Oct | 3.9" | 2.9" | 1" | 💧 Light watering |
| Nov | 3.9" | 6.5" | 0" | ✅ Rainfall sufficient |
| Dec | — | 6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Kitsap 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 — Kitsap County, WA
Brussels Sprouts Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 25 | Feb 25 – Mar 11 |
| Transplant Outdoors | March 25 | Mar 25 – Apr 8 |
| Direct Sow | March 4 | Mar 4 – Mar 25 |
| Harvest | June 24 | Jun 24 – Aug 19 |
| Fall Sowing | September 10 | Sep 10 – Sep 24 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors Transplant Outdoors Direct Sow |
| April | Transplant Outdoors |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | Fall Sowing |
| 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 9a
📆 Growing Season
225 days in Kitsap County
Growing Tips for Brussels Sprouts in Kitsap County
Direct sow Brussels Sprouts outdoors after March 25 in Kitsap 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
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Brussels Sprouts in Other Locations
Frequently Asked Questions
When should I plant Brussels Sprouts in Kitsap County, WA?
Kitsap County is in Zone 9a with an average last frost of March 25. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.
What planting zone is Kitsap County, WA?
Kitsap County, Washington is in USDA Hardiness Zone 9a. The average last spring frost is March 25 and first fall frost is November 5.
Your Kitsap County Garden Planner — Free
A 24-page printable planner built for Kitsap 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.