When to Plant Komatsuna in Pierce County, WA
May to-do list for Pierce County, Washington
Your Pierce County, Washington garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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Indoor seed-starting week for komatsuna
These need a head start before your last frost (April 13). Sow into cells now so you're ready to transplant in a few weeks.
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It's harvest week for komatsuna
If you can't use it all right away, check the food-preservation section of your planner.
Coming up in June — start thinking about
- First harvests: komatsuna
Komatsuna (Japanese mustard spinach) is a versatile Asian green with glossy, dark leaves and a mild, sweet flavor. It is extremely cold-hardy and heat-tolerant.
Pierce County, Washington is in USDA Zone 8b. The average last spring frost is April 13 and the first fall frost is October 30, giving you a growing season of approximately 200 days.
At an elevation of 168 feet, Pierce County receives approximately 48.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Komatsuna to ensure they mature before fall.
Pierce County Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-6.2
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 Pierce County
How your county's soil matches Komatsuna's growing requirements.
Soil pH
Your soil pH (5.4–6.2) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Pierce County is excellent for Komatsuna — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.4%) — Komatsuna will thrive.
How to Plant Komatsuna
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Komatsuna
Sow every 4 weeks. Last sowing by Sep 10 to harvest before frost.
For a dedicated fall crop, sow by Aug 21.
Plant Water Budget
Monthly Watering Guide for Komatsuna
Komatsuna needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Komatsuna Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 6.8" | 0" | ❄️ Dormant |
| Feb | — | 5.7" | 0" | ❄️ Dormant |
| Mar | — | 4.4" | 0" | ❄️ Dormant |
| Apr | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| May | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Jun | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Jul | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Aug | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Sep | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Oct | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Nov | — | 7.8" | 0" | ❄️ Dormant |
| Dec | — | 6.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Pierce County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Komatsuna 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.
Komatsuna Planting Timeline — Pierce County, WA
Komatsuna Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 9 | Mar 9 – Mar 23 |
| Transplant Outdoors | April 13 | Apr 13 – Apr 27 |
| Direct Sow | March 30 | Mar 30 – Apr 20 |
| Harvest | May 18 | May 18 – Jun 22 |
| Fall Sowing | August 21 | Aug 21 – Sep 4 |
Plant 0.5" deep · 6" apart · Rows 12" 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
1"/week · Natural rainfall sufficient
📅 Days to Maturity
35–50 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 8b
📆 Growing Season
200 days in Pierce County
Growing Tips for Komatsuna in Pierce County
Direct sow Komatsuna outdoors after April 13 in Pierce County when soil has warmed and frost danger has passed.
Your generous 200.0-day season in Pierce County allows multiple plantings of Komatsuna. Sow every 17.0 days for continuous harvest.
Common pests for Komatsuna 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. One of the most forgiving Asian greens for all seasons. Harvest outer leaves or cut whole plants. Excellent for stir-fries, soups, or salads.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Komatsuna in Other Locations
Frequently Asked Questions
When should I plant Komatsuna in Pierce County, WA?
Pierce County is in Zone 8b with an average last frost of April 13. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.
What planting zone is Pierce County, WA?
Pierce County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 13 and first fall frost is October 30.
Your Pierce County Garden Planner — Free
A 24-page printable planner built for Pierce 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.