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When to plant Komatsuna in Kankakee County, IL

Kankakee County sits in USDA Zone 5b. Plant Komatsuna between April 6 (after last frost on April 20) and April 27. A second sowing from August 5 to August 19 extends the harvest into fall.

When to Plant Komatsuna in Kankakee County, IL

Kankakee County, Illinois Zone 5b June

What to do in June

Welcome to June in Zone 5b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 20
Avg. first frost October 14
Soil temp (4") 68°F
Watering Moderate
Pest pressure High
Daylight 14.9 hrs
  1. Basket week: komatsuna

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

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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.

Kankakee County, Illinois is in USDA Zone 5b. The average last spring frost is April 20 and the first fall frost is October 14, giving you a growing season of approximately 177 days.

At an elevation of 1,113 feet, Kankakee County receives approximately 33.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Komatsuna during the growing season.

Kankakee County, IL (Zone 5b) Moderate season
177 days
Last Spring Frost April 20
177 growing days
First Fall Frost October 14

Kankakee County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.8

Drainage

Well Drained

Komatsuna Planting Risk Windows

Early Start (70% safe) ✓ Fits season (105 days to spare)
Start indoors: Mar 11 Transplant: Apr 15 🍅 Harvest: May 20 – Jun 24
Recommended (50%) ✓ Fits season (107 days to spare)
Start indoors: Mar 16 Transplant: Apr 20 🍅 Harvest: May 25 – Jun 29
Safe Start (90%) ✓ Fits season (102 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Jun 13 – Jul 18

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 Kankakee County

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

Soil pH

Your soil pH (6.1–6.8) is within Komatsuna's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.9%) — Komatsuna will thrive.

How to Plant Komatsuna

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Komatsuna

6
successive plantings in your 177-day season

Sow every 4 weeks. Last sowing by Aug 25 to harvest before frost.

For a dedicated fall crop, sow by Aug 05.

Komatsuna Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 319 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 1.3" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 3.4" 0.9" 💧 Light watering
May 4.3" 4.3" 0" ✅ Rainfall sufficient
Jun 4.3" 3.7" 0.6" 💧 Light watering
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 3.7" 0.6" 💧 Light watering
Sep 4.3" 2.8" 1.5" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Kankakee 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 ~584 GDD — county provides 2,433 GDD Excellent fit

Komatsuna Planting Timeline — Kankakee County, IL

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors March 16 Mar 16 – Mar 30
Transplant Outdoors April 20 Apr 20 – May 4
Direct Sow April 6 Apr 6 – Apr 27
Harvest May 25 May 25 – Jun 29
Fall Sowing August 5 Aug 5 – Aug 19

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Transplant Outdoors Direct Sow
May Transplant Outdoors Harvest
June Harvest
July
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

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

177 days in Kankakee County

Growing Tips for Komatsuna in Kankakee County

Direct sow Komatsuna outdoors after April 20 in Kankakee County when soil has warmed and frost danger has passed.

Your generous 177.0-day season in Kankakee 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

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Komatsuna in Kankakee County, IL?

Kankakee County is in Zone 5b with an average last frost of April 20. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Kankakee County, IL?

Kankakee County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 20 and first fall frost is October 14.

When should I plant Komatsuna in Kankakee County, IL?

In Kankakee County, IL, plant Komatsuna after the last frost (around April 20) and before the first frost (around October 14). Best results when soil holds above 50°F.

What growing zone is Kankakee County, IL for Komatsuna?

Kankakee County sits in USDA Zone 5b. Komatsuna grows reliably in zones 2a through 11b, so it's a good fit here.

Can Komatsuna grow in Kankakee County's climate?

Yes — Komatsuna grows well in Kankakee County's temperate climate. Kankakee County averages a 177-day frost-free season, with last frost around April 20 and first frost around October 14.

🌱

Your Kankakee County Garden Planner — Free

A 22-page printable planner built for Kankakee 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.

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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 Kankakee County, IL. Local conditions may vary. Last updated: June 2026.

Sources & credits

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