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When to plant Kai Lan in Mazon, IL

In Mazon, plant Kai Lan in spring between April 6 and April 27, once soil temps hold above 50°F. Mazon's last frost averages April 20, so time plantings around the expected last-frost window for best survival. For a fall crop, sow between August 8 and August 22 — roughly 45–60 days before the first frost on October 17.

When to Plant Kai Lan in Mazon, IL

Grundy County, Illinois Zone 5b June

Grundy County, Illinois gardeners: here's your June plan

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Grundy County, Illinois.

Avg. last frost April 20
Avg. first frost October 17
Soil temp (4") 68°F
Watering Moderate
Pest pressure High
Daylight 15 hrs

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Kai lan (Chinese broccoli) is a brassica grown for its thick, glossy stems and small flower buds. It has a slightly bitter, broccoli-like flavor essential in Cantonese cooking.

Mazon, Illinois is in USDA Zone 5b. The average last spring frost is April 20 and the first fall frost is October 17, giving you a growing season of approximately 180 days.

At an elevation of 629 feet, Grundy County receives approximately 30.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Kai Lan during the growing season.

Mazon, IL (Zone 5b) Moderate season
180 days
Last Spring Frost April 20
180 growing days
First Fall Frost October 17

Mazon Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7

Drainage

Well Drained

Kai Lan Planting Risk Windows

Early Start (70% safe) ✓ Fits season (105 days to spare)
Start indoors: Mar 10 Transplant: Apr 14 🍅 Harvest: Jun 2 – Jun 30
Recommended (50%) ✓ Fits season (103 days to spare)
Start indoors: Mar 16 Transplant: Apr 20 🍅 Harvest: Jun 8 – Jul 6
Safe Start (90%) ✓ Fits season (98 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Jun 27 – Jul 25

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 Mazon

How your county's soil matches Kai Lan's growing requirements.

Soil pH

Your soil pH (6.1–7.0) is within Kai Lan's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Kai Lan.

How to Plant Kai Lan

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 Kai Lan

4
successive plantings in your 180-day season

Sow every 5.1 weeks. Last sowing by Aug 18 to harvest before frost.

For a dedicated fall crop, sow by Aug 08.

Kai Lan Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 568 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Kai Lan

Kai Lan needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Kai Lan Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 3.6" 0.7" 💧 Light watering
Jun 4.3" 3.3" 1" 💧 Light watering
Jul 4.3" 3.3" 1" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.7" 1.6" 💧 Light watering
Oct 4.3" 2" 2.3" 🚿 Regular watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Grundy County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Kai Lan 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.

Kai Lan needs ~722 GDD — county provides 2,475 GDD Excellent fit

Kai Lan Planting Timeline — Mazon, IL

Kai Lan 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 June 8 Jun 8 – Jul 6
Fall Sowing August 8 Aug 8 – Aug 22

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
June Harvest
July Harvest
August Fall Sowing
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

180 days in Grundy County

Growing Tips for Kai Lan in Mazon

Direct sow Kai Lan outdoors after April 20 in Grundy County when soil has warmed and frost danger has passed.

Your generous 180.0-day season in Grundy County allows multiple plantings of Kai Lan. Sow every 22.0 days for continuous harvest.

Common pests for Kai Lan 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 when flower buds first appear but before they open. Cut stems at the base to encourage side shoots. Prefers cool weather.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

When should I plant Kai Lan in Mazon, IL?

In Mazon, IL, plant Kai Lan after the last frost (around April 20) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Mazon, IL for Kai Lan?

Mazon sits in USDA Zone 5b. Kai Lan grows reliably in zones 2a through 11b, so it's a good fit here.

Can Kai Lan grow in Mazon's climate?

Yes — Kai Lan grows well in Mazon's temperate climate. Mazon averages a 180-day frost-free season, with last frost around April 20 and first frost around October 17.

🌱

Your Grundy County Garden Planner — Free

A 22-page printable planner built for Grundy 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 Grundy County, IL. Local conditions may vary. Last updated: June 2026.