When to Plant Komatsuna in Iosco County, MI
May in the garden — Iosco County, Michigan
Welcome to May in Zone 5b. These are the moves that will have the biggest impact on your growing season.
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Set out komatsuna seedlings
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
Get ahead of June
- Starting indoors: komatsuna
- 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.
Iosco County, Michigan is in USDA Zone 5b. The average last spring frost is May 14 and the first fall frost is October 3, giving you a growing season of approximately 142 days.
At an elevation of 696 feet, Iosco County receives approximately 37.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Komatsuna during the growing season.
Iosco County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-6.9
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 Iosco County
How your county's soil matches Komatsuna's growing requirements.
Soil pH
Your soil pH (6.2–6.9) is within Komatsuna's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Iosco 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 Aug 14 to harvest before frost.
For a dedicated fall crop, sow by Jul 25.
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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | — | 3.8" | 0" | ❄️ Dormant |
| May | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Aug | 4.3" | 4" | 0.3" | 💧 Light watering |
| Sep | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Oct | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Nov | — | 2.8" | 0" | ❄️ Dormant |
| Dec | — | 2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Iosco 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 — Iosco County, MI
Komatsuna Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 9 | Apr 9 – Apr 23 |
| Transplant Outdoors | May 14 | May 14 – May 28 |
| Direct Sow | April 30 | Apr 30 – May 21 |
| Harvest | June 18 | Jun 18 – Jul 23 |
| Fall Sowing | July 25 | Jul 25 – Aug 8 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors 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 5b
📆 Growing Season
142 days in Iosco County
Growing Tips for Komatsuna in Iosco County
Direct sow Komatsuna outdoors after May 14 in Iosco County when soil has warmed and frost danger has passed.
Your generous 142.0-day season in Iosco 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 Iosco County, MI?
Iosco County is in Zone 5b with an average last frost of May 14. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.
What planting zone is Iosco County, MI?
Iosco County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 14 and first fall frost is October 3.
Your Iosco County Garden Planner — Free
A 24-page printable planner built for Iosco County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.