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When to Plant Kai Lan in Billings County, ND

Billings County, North Dakota Zone 4a May

Your May planting checklist for Billings County, North Dakota

Welcome to May in Zone 4a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 19
Avg. first frost September 21
Soil temp (4") 55°F
Watering Moderate
Pest pressure Low
Daylight 14.9 hrs
  1. Harden off and plant kai lan

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Scatter kai lan into prepared beds

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Looking ahead to June
  • Starting indoors: kai lan
  • Fall sowing: kai lan

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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.

Billings County, North Dakota is in USDA Zone 4a. The average last spring frost is May 19 and the first fall frost is September 21, giving you a growing season of approximately 125 days.

At an elevation of 894 feet, Billings County receives approximately 26.2 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Kai Lan to ensure they mature before fall.

Billings County, ND (Zone 4a) Short season
125 days
Last Spring Frost May 19
125 growing days
First Fall Frost September 21
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Billings County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jul 2 – Jul 30
Recommended (50%) ✓ Fits season (48 days to spare)
Start indoors: Apr 7 Transplant: May 19 🍅 Harvest: Jul 7 – Aug 4
Safe Start (90%) ✓ Fits season (46 days to spare)
Start indoors: Apr 21 Transplant: Jun 2 🍅 Harvest: Jul 21 – Aug 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 Billings County

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

Soil pH

Your soil pH (6.5–7.4) is within Kai Lan's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is moderate (4.0%). 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 12 weeks before your first frost date for a fall harvest.

Succession Planting Kai Lan

3
successive plantings in your 125-day season

Sow every 5.1 weeks. Last sowing by Jul 23 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 160 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 1.6" 2.7" 🚿 Regular watering
Jul 4.3" 2.3" 2" 💧 Light watering
Aug 4.3" 2.9" 1.4" 💧 Light watering
Sep 4.3" 2.4" 1.9" 💧 Light watering
Oct 2" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Billings 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 ~682 GDD — county provides 1,625 GDD Excellent fit

Kai Lan Planting Timeline — Billings County, ND

Kai Lan Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 19 May 19 – Jun 2
Direct Sow May 12 May 12 – Jun 2
Harvest July 7 Jul 7 – Aug 4
Fall Sowing June 29 Jun 29 – Jul 13

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow Fall Sowing
July Fall Sowing Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

125 days in Billings County

Growing Tips for Kai Lan in Billings County

Direct sow Kai Lan outdoors after May 19 in Billings County when soil has warmed and frost danger has passed.

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 →

Frequently Asked Questions

When should I plant Kai Lan in Billings County, ND?

Billings County is in Zone 4a with an average last frost of May 19. Plan your Kai Lan planting based on this frost date — see the calendar above for exact timing.

What planting zone is Billings County, ND?

Billings County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 19 and first fall frost is September 21.

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Your Billings County Garden Planner — Free

A 24-page printable planner built for Billings 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 Billings County, ND. 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.