When to Plant Pac Choi in Washington County, OR
May in the garden — Washington County, Oregon
Here's what deserves your attention in Washington County, Oregon this month. Everything below is tailored to Zone 8b and timed around your local frost dates.
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Begin indoor sowing: pac choi
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
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Start harvesting pac choi
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
Looking ahead to June
- First harvests: pac choi
Pac choi (baby bok choy) is a compact variety of Chinese cabbage with tender leaves and crisp stems. It grows quickly and is ideal for containers and small spaces.
Washington County, Oregon is in USDA Zone 8b. The average last spring frost is April 15 and the first fall frost is October 27, giving you a growing season of approximately 195 days.
At an elevation of 352 feet, Washington County receives approximately 47.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Pac Choi during the growing season.
Washington County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.4
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 Washington County
How your county's soil matches Pac Choi's growing requirements.
Soil pH
Your soil pH (5.8–6.4) overlaps with Pac Choi's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Washington County is excellent for Pac Choi — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.7%) — Pac Choi will thrive.
How to Plant Pac Choi
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Pac Choi
Sow every 4.6 weeks. Last sowing by Sep 02 to harvest before frost.
For a dedicated fall crop, sow by Aug 18.
Plant Water Budget
Monthly Watering Guide for Pac Choi
Pac Choi needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Pac Choi Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 7.4" | 0" | ❄️ Dormant |
| Feb | — | 5.7" | 0" | ❄️ Dormant |
| Mar | — | 4.2" | 0" | ❄️ Dormant |
| Apr | 6.5" | 3" | 3.5" | 🚿 Regular watering |
| May | 6.5" | 2.8" | 3.7" | 🚿 Regular watering |
| Jun | 6.5" | 1.7" | 4.8" | 🚿 Regular watering |
| Jul | 6.5" | 0.6" | 5.9" | 🚿 Regular watering |
| Aug | 6.5" | 0.9" | 5.6" | 🚿 Regular watering |
| Sep | 6.5" | 1.9" | 4.6" | 🚿 Regular watering |
| Oct | 6.5" | 3.5" | 3" | 💧 Light watering |
| Nov | — | 7.3" | 0" | ❄️ Dormant |
| Dec | — | 8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Washington County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Pac Choi 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.
Pac Choi Planting Timeline — Washington County, OR
Pac Choi 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 | May 27 | May 27 – Jun 24 |
| Fall Sowing | August 18 | Aug 18 – Sep 1 |
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 | Harvest |
| June | Harvest |
| July | — |
| August | Fall Sowing |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 1-2 times/week
📅 Days to Maturity
40–55 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 8b
📆 Growing Season
195 days in Washington County
Growing Tips for Pac Choi in Washington County
Direct sow Pac Choi outdoors after April 15 in Washington County when soil has warmed and frost danger has passed.
Your generous 195.0-day season in Washington County allows multiple plantings of Pac Choi. Sow every 20.0 days for continuous harvest.
Common pests for Pac Choi in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in spring or fall. Grows best in cool weather. Space 6 inches apart for baby pac choi. Harvest whole plants or cut outer leaves as needed.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Pac Choi in Other Locations
Frequently Asked Questions
When should I plant Pac Choi in Washington County, OR?
Washington County is in Zone 8b with an average last frost of April 15. Plan your Pac Choi planting based on this frost date — see the calendar above for exact timing.
What planting zone is Washington County, OR?
Washington County, Oregon is in USDA Hardiness Zone 8b. The average last spring frost is April 15 and first fall frost is October 27.
Your Washington County Garden Planner — Free
A 24-page printable planner built for Washington 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.