When to plant Komatsuna in Plymouth County County,
Plant Komatsuna in Plymouth County County, when soil hits 50°F — usually April 16. Continue planting through May 7 for the spring crop. A second sowing from July 28 to August 11 extends the harvest into fall.
When to Plant Komatsuna in Plymouth County, IA
Plymouth County, Iowa gardeners: here's your June plan
Your garden in Plymouth County, Iowa is working on a schedule, even when you're not. Here's where you should be this June.
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Get komatsuna seeds going inside
These need a head start before your last frost (April 30). Sow into cells now so you're ready to transplant in a few weeks.
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Harvest komatsuna as they ripen
If you can't use it all right away, check the food-preservation section of your planner.
July will be here before you know it — start on
- First harvests: komatsuna
- Fall sowing: 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.
Plymouth County, Iowa is in USDA Zone 5a. The average last spring frost is April 30 and the first fall frost is October 6, giving you a growing season of approximately 159 days.
At an elevation of 1,392 feet, Plymouth County receives approximately 38 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.
Plymouth County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7.2
Drainage
Well Drained
Komatsuna 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 Plymouth County
How your county's soil matches Komatsuna's growing requirements.
Soil pH
Your soil pH (6.0–7.2) is within Komatsuna's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Plymouth County is excellent for Komatsuna — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.7%) — 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 Aug 17 to harvest before frost.
For a dedicated fall crop, sow by Jul 28.
Komatsuna 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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.6" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| May | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Jul | 4.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Oct | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Nov | — | 2.8" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Plymouth 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 — Plymouth County, IA
Komatsuna Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 26 | Mar 26 – Apr 9 |
| Transplant Outdoors | April 30 | Apr 30 – May 14 |
| Direct Sow | April 16 | Apr 16 – May 7 |
| Harvest | June 4 | Jun 4 – Jul 9 |
| Fall Sowing | July 28 | Jul 28 – Aug 11 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Fall Sowing Harvest |
| August | Fall Sowing |
| September | — |
| 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: ideal
🗺️ USDA Zone
Zone 5a
📆 Growing Season
159 days in Plymouth County
Growing Tips for Komatsuna in Plymouth County
Direct sow Komatsuna outdoors after April 30 in Plymouth County when soil has warmed and frost danger has passed.
Your generous 159.0-day season in Plymouth 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 Plymouth County, IA?
Plymouth County is in Zone 5a with an average last frost of April 30. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.
What planting zone is Plymouth County, IA?
Plymouth County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 30 and first fall frost is October 6.
When should I plant Komatsuna in Plymouth County County, ?
In Plymouth County County, , plant Komatsuna after the last frost (around April 30) and before the first frost (around October 6). Best results when soil holds above 50°F.
What growing zone is Plymouth County County, for Komatsuna?
Plymouth County County sits in USDA Zone 5a. Komatsuna grows reliably in zones 2a through 11b, so it's a good fit here.
Can Komatsuna grow in Plymouth County County's climate?
Yes — Komatsuna grows well in Plymouth County County's temperate climate. Plymouth County County averages a 159-day frost-free season, with last frost around April 30 and first frost around October 6.
Your Plymouth County Garden Planner — Free
A 22-page printable planner built for Plymouth County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.