When to Plant Mizuna in Iowa County, WI
May to-do list for Iowa County, Wisconsin
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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Plant out mizuna
Frost risk is low now in Iowa County, Wisconsin. If you've been covering beds overnight, you can stop.
Get ahead of June
- Starting indoors: mizuna
- First harvests: mizuna
Mizuna is a mild-flavored Japanese mustard green with feathery, deeply serrated leaves. It is fast-growing and makes an excellent addition to salads and stir-fries.
Iowa County, Wisconsin is in USDA Zone 5a. The average last spring frost is May 3 and the first fall frost is October 7, giving you a growing season of approximately 157 days.
At an elevation of 602 feet, Iowa County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Mizuna to ensure they mature before fall.
Iowa County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.1
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 Iowa County
How your county's soil matches Mizuna's growing requirements.
Soil pH
Your soil pH (5.8–7.1) overlaps with Mizuna's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Iowa County is excellent for Mizuna — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (4.0%). Annual compost additions will help Mizuna.
How to Plant Mizuna
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Mizuna
Sow every 3.4 weeks. Last sowing by Aug 23 to harvest before frost.
For a dedicated fall crop, sow by Jul 29.
Plant Water Budget
Monthly Watering Guide for Mizuna
Mizuna needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Mizuna Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 3" | 0" | ❄️ Dormant |
| Apr | — | 3.5" | 0" | ❄️ Dormant |
| May | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jun | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jul | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Aug | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Sep | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Oct | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Iowa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Mizuna 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.
Mizuna Planting Timeline — Iowa County, WI
Mizuna Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 29 | Mar 29 – Apr 12 |
| Transplant Outdoors | May 3 | May 3 – May 17 |
| Direct Sow | April 19 | Apr 19 – May 10 |
| Harvest | June 7 | Jun 7 – Jul 5 |
| Fall Sowing | July 29 | Jul 29 – Aug 12 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| 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 · Only during dry spells
📅 Days to Maturity
30–45 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
157 days in Iowa County
Growing Tips for Mizuna in Iowa County
Direct sow Mizuna outdoors after May 03 in Iowa County when soil has warmed and frost danger has passed.
Your generous 157.0-day season in Iowa County allows multiple plantings of Mizuna. Sow every 15.0 days for continuous harvest.
Common pests for Mizuna 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. Harvest outer leaves as needed for a cut-and-come-again approach. Mizuna is one of the most cold-tolerant Asian greens.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Mizuna in Other Locations
Frequently Asked Questions
When should I plant Mizuna in Iowa County, WI?
Iowa County is in Zone 5a with an average last frost of May 3. Plan your Mizuna planting based on this frost date — see the calendar above for exact timing.
What planting zone is Iowa County, WI?
Iowa County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is May 3 and first fall frost is October 7.
Your Iowa County Garden Planner — Free
A 24-page printable planner built for Iowa 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.