Blog

When to Plant Komatsuna in Fresno County, CA

Fresno County, California Zone 9b May

Top priorities for Fresno County, California gardeners in May

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

Avg. last frost March 2
Avg. first frost November 23
Soil temp (4") 72°F
Watering Critical
Pest pressure High
Daylight 14 hrs
  1. Harvest komatsuna as they ripen

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

Instant PDF download. No spam, unsubscribe any time.

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.

Fresno County, California is in USDA Zone 9b. The average last spring frost is March 2 and the first fall frost is November 23, giving you a growing season of approximately 266 days.

At an elevation of 2,276 feet, Fresno County receives approximately 14.9 inches of rainfall annually with predominantly loam soil. Summer highs average 100°F, so Komatsuna may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Komatsuna successfully. Mulch heavily to conserve soil moisture.

Fresno County, CA (Zone 9b) Long season
266 days
Last Spring Frost March 2
266 growing days
First Fall Frost November 23
Share this guide:

Fresno County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (197 days to spare)
Start indoors: Jan 19 Transplant: Feb 16 🍅 Harvest: Mar 23 – Apr 27
Recommended (50%) ✓ Fits season (196 days to spare)
Start indoors: Feb 2 Transplant: Mar 2 🍅 Harvest: Apr 6 – May 11
Safe Start (90%) ✓ Fits season (148 days to spare)
Start indoors: Apr 13 Transplant: May 11 🍅 Harvest: Jun 15 – Jul 20

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 Fresno County

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

Soil pH

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

Soil Texture

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

Organic Matter

Organic matter is moderate (3.2%). Annual compost additions will help Komatsuna.

How to Plant Komatsuna

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

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Komatsuna

9
successive plantings in your 266-day season

Sow every 4 weeks. Last sowing by Oct 04 to harvest before frost.

For a dedicated fall crop, sow by Sep 28.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.2″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 2,173 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

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 2.8" 0" ❄️ Dormant
Feb 3.3" 0" ❄️ Dormant
Mar 4.3" 2.3" 2" 💧 Light watering
Apr 4.3" 1" 3.3" 🚿 Regular watering
May 4.3" 0.4" 3.9" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.6" 3.7" 🚿 Regular watering
Nov 4.3" 1.3" 3" 🚿 Regular watering
Dec 2.8" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Fresno 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 ~1,062 GDD — county provides 6,650 GDD Excellent fit

Komatsuna Planting Timeline — Fresno County, CA

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors February 2 Feb 2 – Feb 16
Transplant Outdoors March 2 Mar 2 – Mar 16
Direct Sow February 9 Feb 9 – Mar 2
Harvest April 6 Apr 6 – May 11
Fall Sowing September 28 Sep 28 – Oct 12

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors Direct Sow
March Transplant Outdoors Direct Sow
April Harvest
May Harvest
June
July
August
September Fall Sowing
October Fall Sowing
November
December
Share this guide:

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 9b

📆 Growing Season

266 days in Fresno County

Growing Tips for Komatsuna in Fresno County

Direct sow Komatsuna outdoors after March 02 in Fresno County when soil has warmed and frost danger has passed.

With summer highs reaching 100°F in Fresno County, provide afternoon shade for Komatsuna and water deeply in the morning.

Your generous 266.0-day season in Fresno 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.

Fresno County receives only 15" of rain annually. Komatsuna needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Fresno County, CA?

Fresno County is in Zone 9b with an average last frost of March 2. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Fresno County, CA?

Fresno County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 2 and first fall frost is November 23.

🌱

Your Fresno County Garden Planner — Free

A 24-page printable planner built for Fresno County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Fresno County, CA. 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.