When to Plant Mizuna in Walworth County, SD
May in the garden — Walworth County, South Dakota
Here's what deserves your attention in Walworth County, South Dakota this month. Everything below is tailored to Zone 4b and timed around your local frost dates.
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Get mizuna in the ground
Frost risk is low now in Walworth County, South Dakota. If you've been covering beds overnight, you can stop.
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Seed mizuna outdoors
Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.
Before June arrives, get these ready
- 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.
Walworth County, South Dakota is in USDA Zone 4b. The average last spring frost is May 10 and the first fall frost is October 1, giving you a growing season of approximately 144 days.
At an elevation of 1,070 feet, Walworth County receives approximately 30.2 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Mizuna to ensure they mature before fall.
Walworth County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.8
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 Walworth County
How your county's soil matches Mizuna's growing requirements.
Soil pH
Your soil pH (6.5–7.8) overlaps with Mizuna's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Walworth County is excellent for Mizuna — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.5%). Annual compost additions will help Mizuna.
How to Plant Mizuna
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Mizuna
Sow every 3.4 weeks. Last sowing by Aug 17 to harvest before frost.
For a dedicated fall crop, sow by Jul 09.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 2.1" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.6" | 0" | ❄️ Dormant |
| Apr | — | 2.9" | 0" | ❄️ Dormant |
| May | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Jun | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Jul | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Aug | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Sep | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Oct | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Nov | — | 2" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Walworth 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 — Walworth County, SD
Mizuna Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 29 | Mar 29 – Apr 12 |
| Transplant Outdoors | May 10 | May 10 – May 24 |
| Direct Sow | May 3 | May 3 – May 24 |
| Harvest | June 14 | Jun 14 – Jul 12 |
| Fall Sowing | July 9 | Jul 9 – Jul 23 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Fall Sowing Harvest |
| August | — |
| 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 4b
📆 Growing Season
144 days in Walworth County
Growing Tips for Mizuna in Walworth County
Direct sow Mizuna outdoors after May 10 in Walworth County when soil has warmed and frost danger has passed.
Your generous 144.0-day season in Walworth 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 Walworth County, SD?
Walworth County is in Zone 4b with an average last frost of May 10. Plan your Mizuna planting based on this frost date — see the calendar above for exact timing.
What planting zone is Walworth County, SD?
Walworth County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 10 and first fall frost is October 1.
Your Walworth County Garden Planner — Free
A 24-page printable planner built for Walworth County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.