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When to Plant Komatsuna in Lake County, MN

Lake County, Minnesota Zone 4a May

May in the garden — Lake County, Minnesota

Your garden in Lake County, Minnesota is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost June 1
Avg. first frost September 12
Soil temp (4") 51°F
Watering Low
Pest pressure Low
Daylight 14.9 hrs
  1. Outdoor sowing time: komatsuna

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

A few tasks this May that'll pay off in June
  • Transplants going out: komatsuna
  • Fall sowing: komatsuna

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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.

Lake County, Minnesota is in USDA Zone 4a. The average last spring frost is June 1 and the first fall frost is September 12, giving you a growing season of approximately 103 days.

At an elevation of 1,191 feet, Lake County receives approximately 36.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Komatsuna to ensure they mature before fall.

Lake County, MN (Zone 4a) Short season
103 days
Last Spring Frost June 1
103 growing days
First Fall Frost September 12

Lake County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (37 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jun 24 – Jul 29
Recommended (50%) ✓ Fits season (33 days to spare)
Start indoors: Apr 20 Transplant: Jun 1 🍅 Harvest: Jul 6 – Aug 10
Safe Start (90%) ✓ Fits season (43 days to spare)
Start indoors: May 7 Transplant: Jun 18 🍅 Harvest: Jul 23 – Aug 27

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 Lake County

How your county's soil matches Komatsuna's growing requirements.

Soil pH

Your soil pH (5.9–6.8) overlaps with Komatsuna's range (6.0–7.5), though not a perfect match.

Soil Texture

The silt loam soil in Lake County is excellent for Komatsuna — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Komatsuna.

Organic Matter

Organic matter is excellent (5.1%) — Komatsuna will thrive.

How to Plant Komatsuna

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Komatsuna

3
successive plantings in your 103-day season

Sow every 4 weeks. Last sowing by Jul 24 to harvest before frost.

For a dedicated fall crop, sow by Jun 20.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 1.4" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 3.2" 0" ❄️ Dormant
May 4.6" 0" ❄️ Dormant
Jun 4.3" 5.2" 0" ✅ Rainfall sufficient
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 2.4" 0" ❄️ Dormant
Nov 2.3" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Lake 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 needs ~457 GDD — county provides 1,107 GDD Excellent fit

Komatsuna Planting Timeline — Lake County, MN

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 20 Apr 20 – May 4
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 25 May 25 – Jun 15
Harvest July 6 Jul 6 – Aug 10
Fall Sowing June 20 Jun 20 – Jul 4

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow Fall Sowing
July Fall Sowing Harvest
August Harvest
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: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

103 days in Lake County

Growing Tips for Komatsuna in Lake County

Direct sow Komatsuna outdoors after June 01 in Lake County when soil has warmed and frost danger has passed.

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

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Komatsuna in Lake County, MN?

Lake County is in Zone 4a with an average last frost of June 1. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lake County, MN?

Lake County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is June 1 and first fall frost is September 12.

🌱

Your Lake County Garden Planner — Free

A 24-page printable planner built for Lake County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Lake County, MN. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.