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When to Plant Mustard Greens in North Slope Borough, AK

North Slope Borough, Alaska Zone 2b May

What to do in May

We've pulled the most time-sensitive tasks for North Slope Borough, Alaska this May and put them front and centre. Tackle them in order.

Soil temp (4") 42°F
Watering Critical
Pest pressure Low
Daylight 20.6 hrs

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Mustard greens are fast-growing brassicas with a spicy, peppery kick. They come in green, red, and purple varieties and are excellent cooked or in salads.

North Slope Borough, Alaska is in USDA Zone 2b. The average last spring frost is May 27 and the first fall frost is July 31, giving you a growing season of approximately 65 days.

At an elevation of 2,600 feet, North Slope Borough receives approximately 16.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 69°F, so choose short-season varieties of Mustard Greens to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mustard Greens successfully. Mulch heavily to conserve soil moisture.

North Slope Borough, AK (Zone 2b) Very short season
65 days
Last Spring Frost May 27
65 growing days
First Fall Frost July 31
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North Slope Borough Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (85 days to spare)
Start indoors: Mar 4 Transplant: Apr 15 🍅 Harvest: May 20 – Jul 22
Recommended (50%) ✓ Fits season (85 days to spare)
Start indoors: Mar 4 Transplant: Apr 15 🍅 Harvest: May 20 – Jul 22
Safe Start (90%) ✓ Fits season (85 days to spare)
Start indoors: Mar 4 Transplant: Apr 15 🍅 Harvest: May 20 – Jul 22

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 North Slope Borough

How your county's soil matches Mustard Greens's growing requirements.

Soil pH

Your soil pH (4.9–6.7) is more acidic than Mustard Greens prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in North Slope Borough is excellent for Mustard Greens — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Mustard Greens.

Organic Matter

Organic matter is excellent (5.7%) — Mustard Greens will thrive.

How to Plant Mustard Greens

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

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

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Mustard Greens

Mustard Greens needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Mustard Greens Needs Rainfall You Supplement Action
Jan 0.7" 0" ❄️ Dormant
Feb 0.6" 0" ❄️ Dormant
Mar 0.6" 0" ❄️ Dormant
Apr 0.5" 0" ❄️ Dormant
May 3" 0.7" 2.3" 🚿 Regular watering
Jun 3" 1.2" 1.8" 🚿 Regular watering
Jul 3" 2.2" 0.8" 💧 Light watering
Aug 2.4" 0" ❄️ Dormant
Sep 3.1" 0" ❄️ Dormant
Oct 2.2" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Jul in North Slope Borough). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Mustard Greens 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.

Mustard Greens needs ~70 GDD — county provides 113 GDD Excellent fit

Mustard Greens Planting Timeline — North Slope Borough, AK

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors April 15 Apr 15 – Apr 29
Transplant Outdoors May 27 May 27 – Jun 10
Direct Sow May 20 May 20 – Jun 10
Harvest July 1 Jul 1 – Sep 2
Fall Sowing May 8 May 8 – May 22

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 Fall Sowing
June Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 2b

📆 Growing Season

65 days in North Slope Borough

Growing Tips for Mustard Greens in North Slope Borough

Common pests for Mustard Greens 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 early spring or fall. Harvest young leaves for milder flavor. Plants bolt quickly in heat so grow as a cool-season crop or provide shade.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mustard Greens in North Slope Borough, AK?

North Slope Borough is in Zone 2b with an average last frost of May 27. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is North Slope Borough, AK?

North Slope Borough, Alaska is in USDA Hardiness Zone 2b. The average last spring frost is May 27 and first fall frost is July 31.

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Your North Slope Borough Garden Planner — Free

A 24-page printable planner built for North Slope Borough (Zone 2b). 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 North Slope 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.