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When to Plant Kai Lan in Johnston County, OK

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.

Johnston County, Oklahoma is in USDA Zone 7b. The average last spring frost is March 25 and the first fall frost is November 11, giving you a growing season of approximately 231 days.

At an elevation of 700 feet, Johnston County receives approximately 32.9 inches of rainfall annually with predominantly loam soil. Summer highs average 92ยฐF, providing good warmth for Kai Lan during the growing season.

Johnston County, OK (Zone 7b) Long season
231 days
Last Spring Frost March 25
231 growing days
First Fall Frost November 11

Johnston County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (155 days to spare)
Start indoors: Feb 6 Transplant: Mar 13 🍅 Harvest: May 1 – May 29
Recommended (50%) ✓ Fits season (154 days to spare)
Start indoors: Feb 18 Transplant: Mar 25 🍅 Harvest: May 13 – Jun 10
Safe Start (90%) ✓ Fits season (151 days to spare)
Start indoors: Mar 11 Transplant: Apr 15 🍅 Harvest: Jun 3 – Jul 1

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 826 gal / 100 sq ft
Kai Lan needs ~998 GDD — county provides 4,389 GDD Excellent fit

Kai Lan Planting Timeline โ€” Johnston County, OK

Kai Lan Planting Calendar

Activity When Date Range
Start Indoors February 18 Feb 18 โ€“ Mar 4
Transplant Outdoors March 25 Mar 25 โ€“ Apr 8
Direct Sow March 11 Mar 11 โ€“ Apr 1
Fall Sowing September 2 Sep 2 โ€“ Sep 16
Harvest May 13 May 13 โ€“ Jun 10

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

45โ€“60 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 7b

Growing Season

231 days

Growing Tips for Johnston County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Kai Lan in Johnston County, OK?

Johnston County is in Zone 7b with an average last frost of March 25. Plan your Kai Lan planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Johnston County, OK?

Johnston County, Oklahoma is in USDA Hardiness Zone 7b. The average last spring frost is March 25 and first fall frost is November 11.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Johnston County gardeners in Zone 7b organize planting dates, track what's growing, and never miss a planting window.

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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 Johnston County, OK. Local conditions may vary. Last updated: April 2026.