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When to Plant Komatsuna in Robertson County, TN

Robertson County, Tennessee Zone 6b April

Robertson County, Tennessee gardeners: here's your April plan

Welcome to April in Zone 6b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 6
Avg. first frost October 29
Soil temp (4") 42°F
Watering Moderate
Pest pressure Low
Daylight 12.9 hrs
  1. Plant out komatsuna

    Frost risk is low now in Robertson County, Tennessee. If you've been covering beds overnight, you can stop.

May prep starts now
  • 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.

Robertson County, Tennessee is in USDA Zone 6b. The average last spring frost is April 6 and the first fall frost is October 29, giving you a growing season of approximately 206 days.

At an elevation of 3,620 feet, Robertson County receives approximately 42.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Komatsuna during the growing season.

Robertson County, TN (Zone 6b) Long season
206 days
Last Spring Frost April 6
206 growing days
First Fall Frost October 29

Robertson County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (137 days to spare)
Start indoors: Feb 23 Transplant: Mar 30 🍅 Harvest: May 4 – Jun 8
Recommended (50%) ✓ Fits season (136 days to spare)
Start indoors: Mar 2 Transplant: Apr 6 🍅 Harvest: May 11 – Jun 15
Safe Start (90%) ✓ Fits season (136 days to spare)
Start indoors: Mar 15 Transplant: Apr 19 🍅 Harvest: May 24 – Jun 28

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 Robertson County

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

Soil pH

Your soil pH (5.3–7.0) overlaps with Komatsuna's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.1%). 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

7
successive plantings in your 206-day season

Sow every 4 weeks. Last sowing by Sep 09 to harvest before frost.

For a dedicated fall crop, sow by Aug 20.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 280 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 3.1" 0" ❄️ Dormant
Feb 3.8" 0" ❄️ Dormant
Mar 3.7" 0" ❄️ Dormant
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 3.6" 0.7" 💧 Light watering
Jun 4.3" 3.5" 0.8" 💧 Light watering
Jul 4.3" 4.6" 0" ✅ Rainfall sufficient
Aug 4.3" 4.4" 0" ✅ Rainfall sufficient
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 3.4" 0" ❄️ Dormant
Dec 3.7" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Robertson 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 ~648 GDD — county provides 3,141 GDD Excellent fit

Komatsuna Planting Timeline — Robertson County, TN

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors March 2 Mar 2 – Mar 16
Transplant Outdoors April 6 Apr 6 – Apr 20
Direct Sow March 23 Mar 23 – Apr 13
Harvest May 11 May 11 – Jun 15
Fall Sowing August 20 Aug 20 – Sep 3

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

206 days in Robertson County

Growing Tips for Komatsuna in Robertson County

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

Your generous 206.0-day season in Robertson 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 Robertson County, TN?

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

What planting zone is Robertson County, TN?

Robertson County, Tennessee is in USDA Hardiness Zone 6b. The average last spring frost is April 6 and first fall frost is October 29.

🌱

Your Robertson County Garden Planner — Free

A 24-page printable planner built for Robertson County (Zone 6b). 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 Robertson County, TN. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.