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When to Plant Komatsuna in Denali Borough, AK

Denali Borough, Alaska Zone 2a May

Your May gardening checklist

Each item below is timed to Denali Borough, Alaska's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost June 2
Avg. first frost August 25
Soil temp (4") 41°F
Watering Critical
Pest pressure Low
Daylight 17.8 hrs
  1. Plant komatsuna from seed, right in the garden

    Your soil is 41°F — warm enough for these to germinate without babying.

A few tasks this May that'll pay off in June
  • Transplants going out: komatsuna
  • Fall sowing: 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.

Denali Borough, Alaska is in USDA Zone 2a. The average last spring frost is June 2 and the first fall frost is August 25, giving you a growing season of approximately 84 days.

At an elevation of 2,930 feet, Denali Borough receives approximately 15.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 70°F, so choose short-season varieties of Komatsuna to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Komatsuna successfully. Mulch heavily to conserve soil moisture.

Denali Borough, AK (Zone 2a) Very short season
84 days
Last Spring Frost June 2
84 growing days
First Fall Frost August 25

Denali Borough Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Apr 16 Transplant: May 28 🍅 Harvest: Jul 2 – Aug 6
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Apr 21 Transplant: Jun 2 🍅 Harvest: Jul 7 – Aug 11
Safe Start (90%) ✓ Fits season (4 days to spare)
Start indoors: May 10 Transplant: Jun 21 🍅 Harvest: Jul 26 – Aug 30

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 Denali Borough

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

Soil pH

Your soil pH (5.2–6.6) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Denali 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 (6.0%) — Komatsuna will thrive.

How to Plant Komatsuna

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Komatsuna

2
successive plantings in your 84-day season

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

For a dedicated fall crop, sow by Jun 02.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/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 0.8" 0" ❄️ Dormant
Feb 0.6" 0" ❄️ Dormant
Mar 0.6" 0" ❄️ Dormant
Apr 0.5" 0" ❄️ Dormant
May 0.7" 0" ❄️ Dormant
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 1.7" 2.6" 🚿 Regular watering
Aug 4.3" 2.7" 1.6" 💧 Light watering
Sep 2.8" 0" ❄️ Dormant
Oct 2" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Aug in Denali 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 ~106 GDD — county provides 210 GDD Excellent fit

Komatsuna Planting Timeline — Denali Borough, AK

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 21 Apr 21 – May 5
Transplant Outdoors June 2 Jun 2 – Jun 16
Direct Sow May 26 May 26 – Jun 16
Harvest July 7 Jul 7 – Aug 11
Fall Sowing June 2 Jun 2 – Jun 16

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow Fall Sowing
July Harvest
August Harvest
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 2a

📆 Growing Season

84 days in Denali Borough

Growing Tips for Komatsuna in Denali Borough

Direct sow Komatsuna outdoors after June 02 in Denali Borough when soil has warmed and frost danger has passed.

Common pests for Komatsuna in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

Denali Borough receives only 16" 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 Denali Borough, AK?

Denali Borough is in Zone 2a with an average last frost of June 2. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Denali Borough, AK?

Denali Borough, Alaska is in USDA Hardiness Zone 2a. The average last spring frost is June 2 and first fall frost is August 25.

🌱

Your Denali Borough Garden Planner — Free

A 24-page printable planner built for Denali Borough (Zone 2a). 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 Denali 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.