When to Plant Bok Choy in Whatcom County, WA
Top priorities for Whatcom County, Washington gardeners in May
Your garden in Whatcom County, Washington is working on a schedule, even when you're not. Here's where you should be this May.
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Begin indoor sowing: bok choy
These need a head start before your last frost (April 6). Sow into cells now so you're ready to transplant in a few weeks.
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Pick bok choy
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
Get ahead of June
- First harvests: bok choy
Bok choy is a Chinese cabbage variety with crisp white stalks and dark green leaves. It is a fast-growing cool-season crop ideal for stir-fries and soups.
Whatcom County, Washington is in USDA Zone 8a. The average last spring frost is April 6 and the first fall frost is October 29, giving you a growing season of approximately 206 days.
At an elevation of 386 feet, Whatcom County receives approximately 49 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Bok Choy during the growing season.
Whatcom County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.4
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 Whatcom County
How your county's soil matches Bok Choy's growing requirements.
Soil pH
Your soil pH (5.2–6.4) is more acidic than Bok Choy prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Whatcom County is excellent for Bok Choy — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.7%) — Bok Choy will thrive.
How to Plant Bok Choy
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Bok Choy
Sow every 4.6 weeks. Last sowing by Aug 30 to harvest before frost.
For a dedicated fall crop, sow by Aug 20.
Plant Water Budget
Monthly Watering Guide for Bok Choy
Bok Choy needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Bok Choy Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 6.1" | 0" | ❄️ Dormant |
| Feb | — | 6.2" | 0" | ❄️ Dormant |
| Mar | — | 4.3" | 0" | ❄️ Dormant |
| Apr | 3" | 3.8" | 0" | ✅ Rainfall sufficient |
| May | 3" | 3.1" | 0" | ✅ Rainfall sufficient |
| Jun | 3" | 2.1" | 0.9" | 💧 Light watering |
| Jul | 3" | 0.7" | 2.3" | 🚿 Regular watering |
| Aug | 3" | 0.9" | 2.1" | 🚿 Regular watering |
| Sep | 3" | 2" | 1" | 💧 Light watering |
| Oct | 3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Nov | — | 7.1" | 0" | ❄️ Dormant |
| Dec | — | 8.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Whatcom County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Bok Choy 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.
Bok Choy Planting Timeline — Whatcom County, WA
Bok Choy Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 2 | Mar 2 – Mar 16 |
| Transplant Outdoors | April 6 | Apr 6 – Apr 20 |
| Direct Sow | March 23 | Mar 23 – Apr 13 |
| Harvest | May 18 | May 18 – Jun 22 |
| 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 Direct Sow |
| 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
0.7"/week · Natural rainfall sufficient
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 8a
📆 Growing Season
206 days in Whatcom County
Growing Tips for Bok Choy in Whatcom County
Direct sow Bok Choy outdoors after April 06 in Whatcom County when soil has warmed and frost danger has passed.
Your generous 206.0-day season in Whatcom County allows multiple plantings of Bok Choy. Sow every 20.0 days for continuous harvest.
Common pests for Bok Choy 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 for best results. Keep soil consistently moist. Harvest whole heads or cut outer leaves for a cut-and-come-again approach.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Bok Choy in Other Locations
Frequently Asked Questions
When should I plant Bok Choy in Whatcom County, WA?
Whatcom County is in Zone 8a with an average last frost of April 6. Plan your Bok Choy planting based on this frost date — see the calendar above for exact timing.
What planting zone is Whatcom County, WA?
Whatcom County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 6 and first fall frost is October 29.
Your Whatcom County Garden Planner — Free
A 24-page printable planner built for Whatcom County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.