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When to Plant Komatsuna in Berkshire County, MA

Berkshire County, Massachusetts Zone 5b May

May in Berkshire County, Massachusetts — your action list

We've pulled the most time-sensitive tasks for Berkshire County, Massachusetts this May and put them front and centre. Tackle them in order.

Avg. last frost May 6
Avg. first frost October 12
Soil temp (4") 58°F
Watering Moderate
Pest pressure Low
Daylight 14.4 hrs
  1. Set out komatsuna seedlings

    Your last frost (May 6) has passed. These warm-season crops can handle outdoor soil now.

June will be here before you know it — start on
  • Starting indoors: komatsuna
  • First harvests: komatsuna

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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.

Berkshire County, Massachusetts is in USDA Zone 5b. The average last spring frost is May 6 and the first fall frost is October 12, giving you a growing season of approximately 159 days.

At an elevation of 392 feet, Berkshire County receives approximately 41.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Komatsuna during the growing season.

Berkshire County, MA (Zone 5b) Moderate season
159 days
Last Spring Frost May 6
159 growing days
First Fall Frost October 12
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Berkshire County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (90 days to spare)
Start indoors: Mar 25 Transplant: Apr 29 🍅 Harvest: Jun 3 – Jul 8
Recommended (50%) ✓ Fits season (89 days to spare)
Start indoors: Apr 1 Transplant: May 6 🍅 Harvest: Jun 10 – Jul 15
Safe Start (90%) ✓ Fits season (88 days to spare)
Start indoors: Apr 13 Transplant: May 18 🍅 Harvest: Jun 22 – Jul 27

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 Berkshire County

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

Soil pH

Your soil pH (5.1–6.7) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Komatsuna.

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

5
successive plantings in your 159-day season

Sow every 4 weeks. Last sowing by Aug 23 to harvest before frost.

For a dedicated fall crop, sow by Aug 03.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 3.1" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 3.6" 0" ❄️ Dormant
Apr 3.7" 0" ❄️ Dormant
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 4" 0.3" 💧 Light watering
Jul 4.3" 3.5" 0.8" 💧 Light watering
Aug 4.3" 3.6" 0.7" 💧 Light watering
Sep 4.3" 3.8" 0.5" 💧 Light watering
Oct 4.3" 3.2" 1.1" 💧 Light watering
Nov 3.2" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Berkshire 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 ~616 GDD — county provides 2,305 GDD Excellent fit

Komatsuna Planting Timeline — Berkshire County, MA

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 6 May 6 – May 20
Direct Sow April 22 Apr 22 – May 13
Harvest June 10 Jun 10 – Jul 15
Fall Sowing August 3 Aug 3 – Aug 17

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5b

📆 Growing Season

159 days in Berkshire County

Growing Tips for Komatsuna in Berkshire County

Direct sow Komatsuna outdoors after May 06 in Berkshire County when soil has warmed and frost danger has passed.

Your generous 159.0-day season in Berkshire 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 Berkshire County, MA?

Berkshire County is in Zone 5b with an average last frost of May 6. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Berkshire County, MA?

Berkshire County, Massachusetts is in USDA Hardiness Zone 5b. The average last spring frost is May 6 and first fall frost is October 12.

🌱

Your Berkshire County Garden Planner — Free

A 24-page printable planner built for Berkshire 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 Berkshire County, MA. 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.