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When to Plant Komatsuna in Yakutat City and Borough, AK

Yakutat City and Borough, Alaska Zone 6b May

Your May planting checklist for Yakutat City and Borough, Alaska

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

Avg. last frost May 20
Avg. first frost September 25
Soil temp (4") 62°F
Watering High
Pest pressure Low
Daylight 16.7 hrs
  1. Time to transplant komatsuna

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Put komatsuna seeds straight in the ground

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

Before June arrives, get these ready
  • 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.

Yakutat City and Borough, Alaska is in USDA Zone 6b. The average last spring frost is May 20 and the first fall frost is September 25, giving you a growing season of approximately 128 days.

At an elevation of 246 feet, Yakutat City and Borough receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 66°F, so choose short-season varieties of Komatsuna to ensure they mature before fall.

Yakutat City and Borough, AK (Zone 6b) Short season
128 days
Last Spring Frost May 20
128 growing days
First Fall Frost September 25

Yakutat City and Borough Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Jun 19 – Jul 24
Recommended (50%) ✓ Fits season (58 days to spare)
Start indoors: Apr 15 Transplant: May 20 🍅 Harvest: Jun 24 – Jul 29
Safe Start (90%) ✓ Fits season (55 days to spare)
Start indoors: Apr 27 Transplant: Jun 1 🍅 Harvest: Jul 6 – Aug 10

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 Yakutat City and Borough

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

Soil pH

Your soil pH (5.2–6.3) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Komatsuna.

Organic Matter

Organic matter is excellent (5.1%) — Komatsuna will thrive.

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

4
successive plantings in your 128-day season

Sow every 4 weeks. Last sowing by Aug 06 to harvest before frost.

For a dedicated fall crop, sow by Jul 17.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.3″/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 2.2" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 1.6" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 4.3" 2" 2.3" 🚿 Regular watering
Jun 4.3" 2.7" 1.6" 💧 Light watering
Jul 4.3" 5.1" 0" ✅ Rainfall sufficient
Aug 4.3" 6.8" 0" ✅ Rainfall sufficient
Sep 4.3" 7.5" 0" ✅ Rainfall sufficient
Oct 4.3" 0" ❄️ Dormant
Nov 3.1" 0" ❄️ Dormant
Dec 2.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Yakutat City and Borough). 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 ~0 GDD — county provides 0 GDD May not mature

Komatsuna Planting Timeline — Yakutat City and Borough, AK

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 15 Apr 15 – Apr 29
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 6 May 6 – May 27
Harvest June 24 Jun 24 – Jul 29
Fall Sowing July 17 Jul 17 – Jul 31

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 Harvest
July Fall Sowing Harvest
August
September
October
November
December

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 6b

📆 Growing Season

128 days in Yakutat City and Borough

Growing Tips for Komatsuna in Yakutat City and Borough

Direct sow Komatsuna outdoors after May 20 in Yakutat City and Borough when soil has warmed and frost danger has passed.

Your generous 128.0-day season in Yakutat City and Borough 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 Yakutat City and Borough, AK?

Yakutat City and Borough is in Zone 6b with an average last frost of May 20. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Yakutat City and Borough, AK?

Yakutat City and Borough, Alaska is in USDA Hardiness Zone 6b. The average last spring frost is May 20 and first fall frost is September 25.

🌱

Your Yakutat City and Borough Garden Planner — Free

A 24-page printable planner built for Yakutat City and Borough (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 Yakutat City and Borough, AK. 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.